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Structural mechanics

15th World Conference on Nondestructive Testing

The web site provides access to the proceedings and other information on WCNDT 2000, held in Rome, 15-21 October 2000. The site contains a description of the conference programme, and links to a searchable database that provides access to the full text of the conference papers. The papers can be retrieved either by using a search box or by selecting key word descriptors. Aerospace topics covered in the proceedings include: NDE; acoustic emissions; ultrasonics; turbine blades; condition monitoring; and aging aircraft. The full text papers are available online in HTML format. This is one of the information resouces available via NDT.net.

7th European Conference on Non-Destructive Testing : Proceedings Online

The web site provides access to the proceedings of ECNDT '98, held in Copenhagen, 26-29 May 1998 and ECNDT '02 held in Barcelona, 17-22 June, 2002. The site includes over 500 online abstracts and 100 full text papers from the conference. The technical and scientific sessions can be browsed online and are arranged under the headings of industrial applications and examination methods. The Aerospace Session contains over 50 papers, a proportion of which are available in full text (HTML format). This session covers topics such as: design of modern aircraft structures and the role of NDT; ultrasonic imaging; and NDT in commercial aircraft maintenance. The site is one of the resources available via NDT.net, the e-Journal of Nondestructive Testing & Ultrasonics.

8th European Conference on Non-Destructive Testing : Proceedings Online

The web site provides access to the proceedings of the 8th European Conference on Nondestructive Testing (ECNDT'02), Barcelona (Spain), June 17-21, 2002, organized by the Spanish Society for NDT . The site includes search and browse access to paper titles and a selection of online abstracts and full text papers from the conference. The aerospace session contains some 16 papers in full text. The site is one of the resources available via NDT.net, the e-Journal of Nondestructive Testing & Ultrasonics

A Fully Stochastic Approach to Determine the Lifetime and Inspection Scheme of Aircraft Components

This technical report (NLR-TP-2004-131) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2004 and was written by Frank Grooteman. A fully stochastic fatigue life philosophy SLAP for aircraft components is presented. This approach covers the fatigue crack initiation and growth periods in a realistic way, and avoids important disadvantages of the current deterministic Damage Tolerance approach, which can be very conservative and yet does not give well-defined safety levels (Probability Of Failure). SLAP gives more realistic predictions of component lifetimes and inspection schedules, whereby the required safety level has a primary role in the determination of the inspection schedules. This is demonstrated by an example that uses in-service inspection data for the upper longerons of the F-16 aircraft. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

A Linear Coupling Controller For Plate Vibration

This paper was given at the 5th Dynamics and Control of Systems and Structures in Space (DCSSS) conference by B. Liu, F. Golnaraghi and G. R. Heppler. The conference took place in July 2002 at King's College, Cambridge. A method for optimally placing the actuators for use with a linear coupling controller (LCC) applied to a thin plate with arbitrary boundary conditions is presented. The LCC is is shown to provide good control properties over a wide frequency range. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

A Methodology for the Assessment of the Capability of Inspection Systems for detection of Subsurface Flaws in Aircraft Turbine Engine Components : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-01/96, by R.H. Burkel and others, dated September 2002. A new methodology for determining probability of detection is described. This report includes a general review of various methodologies for determining probability of detection as well as a detailed discussion of the new approach that is being applied to the ultrasonic detection of internal inclusions in the rotating components of aircraft engines. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

A Study into the Response of Aircraft Fuel Tanks to Rapid Decelerations

The site provides access to UK Civil Aviation Authority CAA Paper 2002/7, prepared by the Structures and Materials Department of the CAA's Safety Regulation Group (SRG), issued November 2002. The report presents the results of a study of the dynamics of rapidly decelerating fuel tanks. The objective of the research was to determine the conservatism or otherwise of the existing fuel tank emergency landing requirements based upon hydrostatic pressure criteria. The text of the document is available online in PDF format (17.1 mb) from the CAA's web site.

Advanced Aircraft Materials, Engine Debris Penetration Testing

This technical report (DOT/FAA/AR-03/37) was published by the Federal Aviation Administration (FAA) Office of Aviation Research in December 2005 and was written by Steven J. Lundin and Richard B. Mueller. This report documents the results of testing conducted in July and August 2001 at the Naval Air Warfare Center-Weapons Division, China Lake, CA, as part of the continued effort to characterize uncontained engine events. This effort was performed in support of the Federal Aviation Administration Aircraft Catastrophic Failure Prevention Program. Data generated from this test will support the penetration equation development for the Uncontained Engine Debris Damage Analysis Model (UEDDAM), a developmental design tool for conducting aircraft safety analysis for engine rotor burst events. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Advanced Manufacturing Research Centre (AMRC)

The Advanced Manufacturing Research Centre (AMRC) is a partnership between the University of Sheffield and Boeing. Its aim is to become a world-class global research facility developing innovative and advanced technology solutions for advanced materials forming. The site provides detailed information about AMRC's core research areas (structural integrity, dynamic analysis, damping, surface integrity, virtual reality, machining, complexity, manufacturing management, additive processes and thixo-forming), and a list of publications. Activities within schools and FE colleagues are described as are services that can be offered to industry (e.g. consultancy, rapid prototyping). There is also an FAQ, a news archive, and a career opportunities section. Part of the site is for members only,

Advanced Materials, Manufacturing, and Testing Information Analysis Center (AMMTIAC)

Formed from three pre-existing information analysis centres (AMPTIAC, MTIAC and NTIAC), AMNTIAC's mission is to support the warfighter in all environments. The site provides a library catalogue search, the National Materials Information System (NAMIS - needs a log in), links, and publications, including AMNTIAC Quarterly.

Advanced Polymeric & Metallic Composite Materials for Space and Aerospace Vehicle Structures and Strength Optimization of Composite Structures and their Certification

This is Research and Technology Organization (RTO) AGARD Lecture Series report, AGARD-LS-204, dated December 1995. This lecture series presents and discusses the sci entific problem of advanced polymer and metallic c omposite materials for aerospace structures, stren gth optimization of composite structures, and thei r certification. Some challenges of using composit e structures, including airframe concept definitio n, are studied. Fiber orientation optimization pri nciples for composite panels and shells are outlin ed. Procedures for certification of assemblies mad e out of composites are dealt with. Certification requirements, including requirements to estimate s tatic and fatigue strengths, are formulated. Desig n conditions for composite structures are analyzed , including development. For individual titles, see N96-23937 through N96-23946. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (33 kB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

AEA Technology

AEA Technology focuses on five key areas: technology-based products, specialised science, environmental management, improving the efficiency of industrial plant, and risk assessment and safety management. The site describes the capabilities, products and services of the company. There is a site search facility and a products and services catalogue which can be searched and browsed. The 'investor relations' area provides annual reports and account information from 1997 in PDF format. Up-to-date company news is available.

Aerodynamic interference

This is Research and Technology Organization (RTO) AGARD-CP-71, dated January 1971. The purpose of this Specialist Meeting was t o survey a number of the more important aspects relating t o aerodynamic interference and thereby to provide an understanding of the basic sciences involved, the techniques presently employed and the results of the most recent work in NATO countries. The three-day meeting was arranged as follows with each Session chaired by a member of the Programme Committee: 1. Classical aspects of interference, configuration studies of lift, drag, and high angle of attack characteristics. session I: Wing-Body, and Session 11: Wing-Body-Tail. 2. Airframe-propulsion interference for both commercial and military high performance aircraft. Session 111: Military, and Session IV: Commercial Transport. 3. Aerodynamics dealing with the properties and characteristics of forces and moments exerted on objects in motion and in the vicinity of other shapes. Airframe Stores. This discussion was a very valuable exercise in surveying some of the results presented in this meeting and follows the papers presented in this publication. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (85.5MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

AGARD engine disc cooperative test programme

This is Research and Technology Organization (RTO) AGARD-R-766 , dated August 1988. The initial results of an AGARD test program on fatigue behavior of engine disc materials are described. The first phase of the program, the Core Program, was aimed at test procedure and specimen standardization and calibration of the various laboratories. A detailed working document is included which describes the testing fundamentals and procedures and includes the analysis procedures used for handling the test data. Fatigue crack initiation and propagation testing was performed on Ti-6Al-4V material under room temperature and constant amplitude loading conditions using four different specimen designs. All results were statistically analyzed for possible significant differences in material behavior due to disc processing variables, specimen location in the disc or testing laboratory. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (121.10MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Ageing Mechanisms and Control Symposium : Part A, Developments in Computational Aero- and Hydro-Acoustics Symposium : Part B, Monitoring and Management of Gas Turbine Fleets for Extended Life and Reduced Costs

This site provides access to a Research and Technology Organization Meeting Proceedings, RTO-MP-079(I), Paris, February 2003. The document contains papers presented at the Symposium of the RTO Applied Vehicle Technology Panel (AVT) Specialists' Meeting held in Manchester, United Kingdom, 8-11 October 2001. The objective of the symposium was to create an opportunity for exchange of information on recent and current developments in computational acoustics between specialists in aero-acoustics and hydro-acoustics from the member states of NATO for the benefit of identifying the most successful and promising approaches for the prediction of noise characteristics of air and sea vehicles. Part B of the symposium identified a number of methodologies in use and being developed to allow the safe extension of life for gas turbines used in weapon systems. The papers address a number of topics relating to maintenance and logistics practices, general design practices, usage data and mission analysis, and life determination methodologies. A table of contents, and the full text (82.8 Mbytes) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Aging Aircraft : Implications for Programmed Depot Maintenance and Engine-Support Costs

This provides access to RAND publication CT-149, prepared by Raymond Pyles, dated February 1999. The report is published in the RAND testimony series, as part of the Project Air Force programme. The full text is available in PDF format.

Aging Aircraft Fleets : Structural and Other Subsystem Aspects

This web site provides access to a Research and Technology Organization (RTO) Educational Note, RTO-EN-015, dated March 2001. The document was produced by the RTO's Applied Vehicle Technology Panel (AVT) and the Consultant and Exchange Programme of RTO in support of a Lecture Series presented on 13-16 November 2000 in Sofia, Bulgaria. The lecture series covered a range of topics including: aging systems and sustainment technology; aircraft loads; airframe repair options; risk assessments; airframe corrosion; human factors in aircraft maintenance; engine life extension; equipment health monitoring; corrosion prevention and control; repair software; inspection technologies; and inspection, reliability and human factors. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text of the document (20.8 Mbytes) can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Aging Combat Aircraft Fleets- Long Term Applications

This is Research and Technology Organization(RTO) AGARD Lecture Series, AGARD-LS-206, dated January 1996. It is sponsored by the Advisory Group for Aerospace Research and Development of AGARD. This Lecture Series covers systems update and structural airworthiness aspects of aging, fixed-wing aircraft. It highlights the aspect of retrofit/rejuvenation of aging aircraft through presentations relating to three front-line combat aircraft in NATO's inventory. The presentations describe implementation strategies and ways to improve the ability of an airframe to accommodate new systems to meet present day mission requirements. Technical issues pertaining to structural safety, maintenance management, and proactive rehabilitation/retrofit schemes are also discussed. It provides technical information to fleet operators and managers to assist them to better manage aging aircraft fleets and be able to deal with aging related problems as they arise. It also targets industry personnel responsible for upgrading the capabilities of combat aircraft, maintenance personnel at air logistics centers, and specialists involved with the design of repairs and prescription of inspection methods. 'Aging aircraft' has several connotations, amongst them technological obsolescence, performance upgrading, changing mission requirements unanticipated during design specification and development, the specter of runaway maintenance costs, decreased safety, impairment of fleet readiness, and unavailability of home depot facilities. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (59 Mb)of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Air Force Office of Scientific Research (AFOSR)

This is the home page of the US AFOSR, whose mission is to manage all basic research conducted by the US Air Force. The site provides information on the role, function, and organisation of the AFOSR. Information about doing business with the AFOSR, its education and research assistance programmes, news and a calendar of events are also provided. A particularly useful resource is the link to AFOSR publications, which includes a summary of research highlights and annual research technology area plans.

Air Force Research Laboratory : Space Vehicles Directorate

Space Vehicles is one of nine Air Force Research Laboratories directorates, and its main purpose is to develop technologies that support evolving warfighter requirements to control and exploit space. The keys areas of research include the battlespace environment, protection of space assets, space vehicle control, space-based sensing, space vehicle technologies (structures, power, thermal management) wargaming, and performing a variety of integrated space technology demonstrations. The resources available from the site include news releases, a newsletter, fact sheets, an overview of the directorate's research interests and activities, and a bibliographic database of directorate technical reports, which can be searched and/or browsed.

Aircraft Hardening Research Programme Final Overview Report

The is the PDF version of UK Civil Aviation Authority (CAA) Paper 2001/9, compiled by the Structures and Materials Department, Design and Production Standards Division of the CAA's Safety Regulation Group, published December 2001. The paper presents the results of research undertaken by the CAA and the Department of Transport, into means of mitigating the effects of explosions on civil transport aircraft. The research was carried out under a CAA contract by the Defence Evaluation and Research Agency, now QinetiQ. The mitigation measures studied include extrinsic means such as the use of hardened baggage containers and protective liners for the fuselage skin or spacing materials for the cargo hold. Means to restrict baggage momentum or to distribute baggage are also discussed. Measures to improve the aircraft structure itself including local reinforcement of skin and frames, improved attachment of fuselage stringers and selective placement of systems equipment are also reviewed.

Airframe Inspection Reliability under Field/Depot Conditions

This site provides access to a Research and Technology Organisation Meeting Proceedings, RTO-MP-010, Paris, November,1998. The document contains papers presented at a Workshop on Airframe Inspection Reliability under Field/Depot Conditions organised by the Applied Vehicle Technology Panel (AVT) of RTO, in Brussels, Belgium, 13-14 May 1998. The Workshop had the general objective of promoting general discussion on the merits and practicality of generating NDI Probability of Detection (POD) from in-service data and on the use of reliability data in the life-cycle management process.The papers are presented under the following headings: •Perspectives on:(i) the role of NDI,(ii) factors influencing eddy current POD in the field environment, and iii) NDT reliability •Estimation from small samples and in-service experience •Approaches to POD generation •Analytical issues related to generation and use of POD data •Practical experience and case studies Bibliographic and abstract details are available in HTML format. A table of contents, and the full text of the document(21.3 Mbytes) can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Alleviation of Buffet-Induced Vibration Using Piezoelectric Actuators

This is the full text of a Master's thesis by Captain Shawn D. Morgenstern, USAF, AFIT/GAE/ENY/06-M25, which was presented to the Faculty Graduate School of Engineering and Management of Air University's Air Force Institute of Technology (AFIT), in February 2006. Buffet-induced vibration has been problematic for aircraft structures for many years. The F-16 ventral fin, while prone to these effects, lends itself well to the evaluation of modern active structural and flow control technologies. The objective of this research was to determine the most critical natural modes of vibration for the F-16 ventral fin and design piezoelectric actuators capable of reducing buffet-induced ventral fin vibration. A finite element model (FEM) for the fin was developed, tuned and optimized to closely match published modal frequencies. Piezoelectric actuator patches were designed using the strain characteristics of the FEM and integrated into the model using a thermal analogy which allowed voltage application and the resulting strain to be simulated by a change in temperature. Two phases of critical mode selection were completed and included reviews of existing flight test data, historical ventral fin failure characteristics, and the results of aeroelastic and closed-loop aeroservoelastic analyses conducted on the FEM. Results showed the FEM tuning and optimization procedures, as well as the design and implementation process for the piezoelectric actuators to be very effective. Modes 1, 2 and 4 were determined to be the most suitable for future application of the technology. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

AMMTIAC Quarterly

The AMMTIAC Quarterly is published by the Advanced Materials, Manufacturing, and Testing Information Analysis Center (AMMTIAC). AMMTIAC is a DoD-sponsored Information Analysis Centre. This site provides searchable access to current and previous issues, as well as access to its preceding publication NTIAC Newsletter back to 1999, and to the AMPTIAC Newsletter back to 1999.

An Analysis of Nonlinear Elastic Deformations for a Homogeneous Beam at Varying Tip Loads and Pitch Angles

This is the full text of a Master's thesis by Ensign Robert J. McGraw, USN, AFIT/GAE/ENY/06-J09, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in June 2006. The Princeton beam experiments of 1975 were performed in hopes of producing viable data for beam nonlinear elastic deformation models in hopes of improving helicopter main beam designs. The recorded data, specifically for homogeneous beams of 7075 aluminum, have been referenced as a baseline for the past thirty years to validate numerous computer models and theories in an effort to build beams capable of withstanding aeroelastic, static, and dynamic loading. The purpose of this study is to improve upon the data recorded in 1975 using newer technologies including a laser distance meter, digital inclinometer, and three-dimensional traverse to test X-axis, Y-axis, Z-axis and angular displacements for varying tip loads and pitch angles. Initial beam deformations due to machining stresses were included in the testing, and the beam was analyzed at tip loads between zero and four pounds for positive and negative pitch angles in fifteen-degree increments from zero to ninety degrees. The results were analyzed in numerous comparisons between the different tip loads and pitch angles, and the overall results were compared with Princeton beam data to ensure their validity. The experimental results showed an improvement in terms of precision as well as a relatively close correlation with Princeton beam data. There were some displacement discrepancies, but such differences can be examined in the future. The results can be used for beam vibrational mode and frequency testing as the beam's geometry can be reproduced graphically and computer model verifications, allowing for more precise computer models for homogeneous nonlinear beam displacements. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

An Application of a Reduced Order Computational Methodology for Eddy Current Based Nondestructive Evaluation Techniques

This is a North Carolina State University (NCSU), Department of Applied Mathematics PhD dissertation, by Michele Lynn Joyner, dated 1 June, 2001. It explores the feasibility of detecting hidden corrosion and flaws in structures such as aircraft and pipelines by the application of an eddy current based technique and reduced order modeling. Reduced order Proper Orthogonal Decomposition (POD) techniques are employed for the creation of a set of basis elements spanning a data set consisting of either numerical simulations or experimental data. Two different approaches in forming the POD approximation, a POD/Galerkin technique and a POD/Interpolation technique are investigated. The error in the approximation using one approach versus the other is examined and the results of the parameter estimation problem for both techniques are presented. Finally, results of the parameter estimation problem are given using both simulated data with relative noise added as well as experimental data obtained using a giant magnetoresistive (GMR) sensor. The experimental results are based on successfully using actual experimental data to form the POD basis elements (instead of numerical simulations) thus illustrating the effectiveness of this method on a wide range of applications. Bibliographic and abstract details are available in HTML format. The full text of the document is accessible online in PDF format [3.03 Mb]. This title is part of North Carolina State University's Electronic Thesis and Dissertation (ETD) Collection

An Assessment of Fatigue Damage and Crack Growth Prediction Techniques

This is Research and Technology Organization (RTO) AGARD-R-797, dated March 1994. Fatigue is an important consideration in structural design and monitoring of continued airworthiness of military aircraft. This Workshop titled 'An Assessment of Fatigue Damage and Crack Growth Prediction Techniques' provided a forum for an in-depth discussion of the correlation between in-service experience and results from analytical predictive models, specimen level tests, component tests, and full-scale tests. Additionally, it made possible an examination of the operating standards that different countries adopt with respect to various elements in the design process for assessment of fatigue damage. For individual titles, see N94-34582 through N94-34599. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (66.89MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

An Investigation of a Simplified Gouging Model

This is the full text of a Master's thesis by Captain Gregory S. Rickerd, USAF, AFIT/GAE/ENY/05-M19, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2005. Gouging is a type of structural failure that becomes important when two metals slide against each other at velocities in the range of 1.5 kilometers per second. A computer model has previously been used to model the development of gouging at the Holloman High Speed Test Track. This model has not been experimentally verified to be correct, due to the complexity of the model. This research develops a simplified model that can be experimentally verified. The computer program utilized in this research was studied to determine the most appropriate options to use in simulations. This was accomplished by modeling a Taylor impact test and comparing to published experimental results. The cylindrical impact specimen utilized in the simplified model was developed through use of the Buckingham-Pi theorem, and can be fired from most standard compressed air guns. Simulations using the simplified model showed excellent agreement with simulations using the physical sled properties. Plasticity observed in both the rod and target was very similar to that seen in the physical sled simulations. The high-pressure core, which initiates gouging in the physical sled simulation, was found to exist in the simplified model as well. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

Analyses of Fatigue Crack Growth Databases for Use in a Damage Tolerance Approach for Aircraft Propellers and Rotorcraft

This technical report (DOT/FAA/AR-07/49) was published by the Federal Aviation Administration (FAA) Office of Aviation Research and Development in November 2007 and was written by James C. Newman, Jr. A large portion of the fatigue crack growth threshold data in this report is inappropriate due to the load reduction test procedure that was used to generate these data. The author, in collaboration with National Aeronautics and Space Administration(NASA) Langley Research Center (LaRC) personnel, is developing new test procedures to generate threshold data under steady-state constant-amplitude loading conditions without any load history effects. The new test method involves using compression precracking to generate a crack at a V-notch and then to test the specimen under constant-amplitude loading. A large test program on the development of these fatigue crack growth databases, for use in damage-tolerant analyses for aircraft propellers and rotorcraft components, was conducted at NASA LaRC under a Memorandum of Agreement with the Federal Aviation Administration (FAA). Some materials tested and analyzed herein were 7050-T7451 and 7075-T7351 aluminum alloys and D6AC and 4340 steels. Only the steels were tested as part of the FAA program. The 7075 alloy was tested at the NASA Johnson Space Center, and the 7050 and 7075 alloys were tested at NASA LaRC. This test program was conducted to generate more accurate representations of fatigue crack growth rate behavior in the near-threshold regime and approaching fracture under a wide range of constant stress ratio (R = Pmin/Pmax) conditions. The objective of the proposed research grant was to analyze the test data on selected propeller and rotorcraft materials to develop the effective stress-intensity factor range against crack growth rate relationship for use in damage tolerance analyses. The resulting relationships can then be used in the strip-yield model in NASGRO (Stripy), AFGROW, or used to generate the stress-intensity factor range against crack growth rate curves for use in NASGRO, AFGROW, or any other life-prediction code requiring linear elastic fracture mechanics procedures. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Analysis of Computational Methods for the Treatment of Material Interfaces

This is the full text of a Master's thesis by Captain Minh C. Nguyen, USAF, AFIT/GAE/ENY/05-M15, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2005. Rocket sled tests at the Air Force Research Laboratory's Holloman High Speed Test Track frequently approach velocities where gouging development becomes the limiting factor to achieving higher operating velocities. Direct observation of the gouging process is not possible so computational modeling is necessary to study the phenomenon. Since gouging development is dependent on the impact surface conditions, the method used to model material interfaces directly affects the accuracy of the solution. Three methods are available in the hydrocode CTH to handle material interfaces: 1) materials are joined at the interface, 2) a frictionless slide line is inserted, and 3) a boundary layer interface is established. An axisymmetric impact scenario is used to explore these methods and their influence on high energy impact solutions. The three methods are also compared in an axisymmetric sliding scenario. The method of joining materials at the contact surface appears well suited to the simulation of high energy impact events. The frictionless slide line method produces significant numerical instability, while the boundary layer interface method is too limited for two dimensional applications. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

Analysis of Fatigue Crack Growth from Countersunk Fasterer Holes

This provides access to a Federal Aviation Administration (FAA) DOT/FAA/AR-08/21 written by A. F. Grandt Jr. dated August 2008. This report provides experimental measurements of stress-intensity factors for cracks that develop at countersunk fastener holes. Two configurations were considered: cracks that form at open holes in plates subjected to remote tension and cracks thatoccur at a pin-loaded hole. In both cases, fatigue crack growth tests were conducted with transparent polymer specimens that allowed in situ photographs of the cracks as they progressed through the specimen thickness. The well-known James and Anderson backcalculation technique was then used to convert the measured fatigue crack growth rates to cyclic stress-intensity factors with the fatigue crack growth rate law established for the test material. The stress-intensity factors are presented in dimensionless form as a function of position along the crack tip perimeter for 112 different open-hole cracks and for 76 pin-loaded hole crack configurations. Some results are compared with numerical solutions obtained here and from the literature. The results of all the experiments are recorded in the appendices of this report and are proposed as benchmark solutions to compare with future analysis results. [Taken from abstract]. The full text is available in PDF format so Adobe Acrobat software is required in order to read it.

Analysis of Residual Strength of Flat and Curved Panels, with and Without Stiffeners, with Multiple Site Damage

This technical report (DOT/FAA/AR-06/37) was published by the Federal Aviation Administration (FAA) Office of Aviation Research and Development in December 2006 and was written by M.F.J. Koolloos, F.P. Grooteman and H.J. ten Hoeve. Multiple-site damage (MSD) is a typical problem for aging aircraft. The large number of fuselage pressurization cycles may cause fatigue cracking at multiple rivet locations in the lap joints of an aircraft structure and thereby reduce the overall structural integrity. The residual strength of a panel with a leading crack and MSD cracks is known to be lower than the one for a panel with the same leading crack but without MSD. A lot of research in testing and development of models have been conducted in recent years to assess the residual strength and predict linkup of stiffened flat panels with a leading crack and MSD. But differences exist between the models in terms of definitions and criteria used for crack growth and linkup, and model verification was done with experimental data available from public literature and not from direct experiments. The main objective of this project was to develop an engineering tool that can be used in the design of aircraft. In this research project, a model to predict linkup and residual strength in flat and curved panels with a leading crack and MSD cracks and with or without stiffeners was developed. The model uses the strip yield model (as implemented in the NASGRO software), J-integral, and the compatibility methods. The strip yield method was used to calculate the stresses and deformations at the crack tips. These stresses and deformations were then used in the calculations of the J-integral values at the crack tips. The effect of the stiffeners on the deformation behavior of the panels was implemented by the displacement compatibility method, whereas the panel curvature was modelled using bulging factors. Finally, the model was verified with experimental data obtained from testing the flat and curved panels with or without stiffeners. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Analytical Modeling of ASTM Lap Shear Adhesive Specimens : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/130, by Charles Yang, John S Tomblin, and Guan, Zhidong, dated February 2003. An analytical model was developed to predict the stress distribution within the specimen specified in ASTM D 3165 �Strength Properties of Adhesives in Shear by Tension Loading of Single-Lap-Joint Laminated Assemblies.� The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Application of Damage Tolerance Principles for Improved Airworthiness of Rotorcraft

This web site provides access to a NATO Research and Technology Organization (RTO) report titled: Application of Damage Tolerance Principles for Improved Airworthiness of Rotorcraft, RTO-Mp-024, February 2000. The report contains papers presented at the Applied Vehicle Technology Panel (AVT) Specialists Meeting, held in Corfu, Greece, 21-22 April 1999. The metting addressed issues associated with aging systems, and in particular with the application of damage tolerance principles for improved airworthiness of rotorcraft. The papers were grouped into three sessions covering the following: materials data and crack growth models for damage tolerance approaches to helicopter structures; design application of DT principles; and operator experience and certification issues. The citation and abstract information is in HTML format, and the full text is available online in PDF format (23 Mbytes).

Applied Aerospace Structures Corporation

This is the web site of the Applied Aerospace Structures Corporation (AASC), a US company involved in the manufacture of lightweight composites and metallic structures and components for space and aircraft applications. The focus of the company is on creating high strength lightweight structures for aircraft and spacecraft. The site gives some background information about the company and also gives details about its products and services. These are divided into five main product areas - space, aircraft, precision structures, ground systems, engineering and testing. It is possible to view the full text of the company's press releases.

ASME Digital Library

This service allows you to search ASME (American Society of Mechanical Engineers) journal articles back to 1985 and conference proceedings back to 2002. Search results provide bibliographic information and an abstract, with the option to purchase the full text, if you are not a subscriber.

Assessment of Damage Tolerance Standard Test Methods and Development of Crack Growth and Delamination Datanase for Composite Structures

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA/AR-08/47 written by Kunigal Shivakumar and dated January 2009. This research was conducted as a part of the Federal Aviation Administration (FAA) damage tolerance technology development and database generation for composite materials used in rotorcraft and general aviation industries. The objectives of the research were to review the status of the fracture and fatigue testing of composite laminates, develop a total fatigue life prediction model, generate the database of delamination growth rates for mode I loading, determine constants in the total fatigue life model, and verify the model. The present research proposed and developed three total life prediction models. They are (1) a log-log equation with resistance (GR) normalization, (2) a log-linear equation with critical energy release rate (GIC), and (3) a log-log equation with GIC normalizations. All three total life equations were proposed and developed for the first time in the literature. The most promising total life prediction model is the GR normalization. Two material systems were considered in this research: (1) woven-roving Fiber Glass Industries, Inc. (FGI) 1854 E-glass/Dow 510A-40 vinyl ester and (2) unidirectional Toray’s T800H carbon/3900-2 epoxy composites. The glass/vinyl ester composite panel was fabricated by North Carolina A&T developed vacuum-assisted resin transfer molding (VARTM) technique and carbon/epoxy panel by no-bleed autoclave processing. Fracture resistance test data was generated by ASTM D 5528 test method. The GIC and GIR data were reduced by modified beam theory, compliance, and modified compliance methods. An automated data reduction program was developed using the Microsoft® Excel® spread sheet. The program is included in the report. Fatigue onset life and delamination growth rate tests were conducted as per the ASTM D 6115 standard. Either 2% or 5% compliance increase criteria was found to be appropriate for predicting the onset life. The asymptotic value of energy release rate from the data generated was about 0.22GIC for glass/vinyl ester. The threshold G (Gth) will be less than the asymptotic value. Fatigue delamination growth rate tests were started with the GImax loading equivalent to 0.8 GIC. For the glass/vinyl ester, the developed delamination growth rate equation was verified for two types of block fatigue loading with R = 0.1. One type of loading was typical service loading while the other was aggressive with high value of GImax. The block loading consisted of GImax rising, constant, and decreasing segments. The GIR normalized delamination growth rate equation agreed very well with experiment for the block loading 1 and reasonably well for block loading 2. The log-linear equation agreed very well with experiment for block loading 1 but was inaccurate for block loading 2. The verification was performed only for glass/vinyl ester composite but not for carbon/epoxy because of thermoplastic interlayer effect. [Taken from abstract]. The full text is available in PDF format so Adobe Acrobat software is required in order to read it.

Assessment of Residual Stresses and Hole Quality on the Fatigue Behavior of Aircraft Structural Joints : Volume 1 Stress Analysis, Fatigue Tests and Life Predictions

This gives access to a Federal Aviation Administration (FAA) report DOT/FAA/AR-07/56, V1 written by James Newman and W. Steven dated March 2009. The aging aircraft research programs conducted by the Federal Aviation Administration (FAA) and the aircraft industry have identified some technology gaps in assessing widespread fatigue damage in aircraft structures. One particular gap is a lack of understanding of the initial stages of multiple-site damage crack formation and growth. This report is the result of a study on the influence of residual stresses and production-quality holes on the fatigue behavior of laboratory coupons, laboratory flat-riveted lap joint specimens, curved-riveted lap joint panels from a narrow-body retired aircraft, and data from the retired aircraft destructive evaluations. The influence of residual stresses is accounted for in the life-prediction methodology by developing stress-intensity factor solutions and codes for both two- and three-dimensional cracked bodies. The influence of the production quality hole is accounted for in the development of equivalent initial flaw size (EIFS) values to fit the experimental test data on the coupons and riveted lap joint panels. A 2024-T3 aluminum alloy sheet material was selected because of its use in the majority of the current fleet of commercial aircraft. National Aeronautics and Space Administration Langley Research Center supplied the material for part of this study. The Lockheed-Martin Aeronautics Company and Delta Air Lines provided production-quality drilled-hole coupons, the two-rivet lap joint specimens, and guidance on the critical parameters that were studied in this investigation. Fatigue life analyses on the polished and production-quality holes and two-rivet lap joint specimens were made using the small crack theory and the usual EIFS values. An assessment on the impact of loose and tight rivets on the fatigue life of more realistic structural configurations was made using the results from the EIFS values determined from laboratory-riveted lap joint panels and previous analyses of test results from a wide-body fuselage aircraft. Studies at Delta Air Lines indicated that the right and left sides of the retired narrow-body (Boeing 727) aircraft had quite different cracking behaviors. Predictions made on the curved panel tests conducted at the FAA Full-Scale Aircraft Structural Test Evaluation and Research facility indicated that the panels on one side of the aircraft could withstand about 90,000 additional pressure cycles to failure (panel had been subjected to about 60,000 flights before testing); whereas, the data and analyses from the destructive teardown of the retired aircraft by Delta Air Lines (lap joints from the other side of the aircraft) indicated that only an additional 10,000 flights would have been required to cause failure, if the fuselage had not been retired, inspected, or repaired. [Taken from abstract]. The full text is available in PDF format so Adobe Acrobat software is required in order to read it.

Assessment of Residual Stresses and Hole Quality on the Fatigue Behavior of Aircraft Structural Joints : Volume 2 Fastener Hole Drilling Quality and Fatigue Lives

This gives access to a Federal Aviation Administration (FAA) report DOT/FAA/AR-07/56,V2 written by Carter Ralph and Steven Johnson dated March 2009. A study was conducted on the effects of drilling fastener holes in 2024-T3 aircraft-quality aluminum. The effects were researched using three techniques: a comparison of four hole surface-quality metrics, x-ray diffraction, and fatigue at three stressintensities. Six production-line factor variables were considered: the experience of the operator, the use of a pilot hole, the length of the bit, the condition of the bit, the axial pressure or feed rate, and the rotational speed of the bit upon withdrawal from the hole. The four hole-quality metrics employed were surface roughness, conicality, the number of large gouge marks, and the angles of those marks. The pilot hole was found to produce the greatest overall effect on hole quality, improving hole quality with its use. X-ray diffraction was used to attempt to measure the relative residual hoop stresses induced by the six drilling factors. Tests found that specimens could not be compared using this method due to problems resulting from the combination of the specimen’s geometry, hole surface quality, and the properties of the aluminum alloy. Fatigue tests were conducted at 25, 21, and 17.5 ksi on as-drilled and chemically polished specimens. These tests suggested that, although residual stresses do appear to have an effect, hole quality is the predominant factor affecting fatigue life. [Taken from abstract]. The full text is available in PDF format so Adobe Acrobat software is required in order to read it.

Assessment of Residual Stresses and Hole Quality on the Fatigue Behavior of Aircraft Structural Joints : Volume 3 Finite Element Simulation of Riveting Process and Fatigue Lives

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA/AR-07/56, V3 written by A. Atre and W. Steven dated March 2009. Aircraft fuselages are fatigue-critical structures, and operational damage in the lap joints have been widely recognized as a safety issue. The Federal Aviation Administration and Delta Air Lines teamed in an effort to conduct destructive evaluation, inspection, and extended fatigue testing of a retired Boeing 727 passenger aircraft near its design service goal. Inspections revealed a large number of cracks in the fuselage joints emanating from the rivet/skin interface. The presence of these cracks was attributed to the sharp stress gradients arising from contact between the installed rivet and the rivet holes. The residual-stress field generated during the rivet installation has a strong impact on the nucleation and propagation of fatigue cracks at and around the rivet/skin interface. The main objective of this research was to establish a link between critical riveting process parameters and the potential of fatigue damage in the joint. The significance of contact and plasticity in the riveting process made the problem well-suited to a finite element (FE) modeling solution. In addition, there was also a need to understand how manufacturing process variations affect the residual-stress state produced in the joint. Both of these objectives were addressed in this research. The study was conducted in four phases. First, a two-dimensional axisymmetric model of the riveting process was developed, which was deliberately designed to simulate previous experiments conducted by a team of Canadian researchers. The second phase used the FE approach and the lessons learned from the first phase to specifically focus on the development of a three-dimensional displacement controlled riveting process model for the lap joint configuration. In the third phase, the residual stress and strain generated from the riveting process models served as an input to a global three-rivet lap joint model designed to approximate the in-service loading experienced by the B727 fuselage splice. Finally, fatigue tests on riveted lap joint specimens were conducted to forge a link between rivet installation and hole-quality effects on fatigue performance of the joint. A comparison of the surface strains predicted by the FE models to the surface strainsof the tested specimen captured through thermal imaging techniques offered an additional source of validation to the analysis. An observed correlation between the fatigue lifetimes of the tested specimens and controlled parameters showed underdriven rivets to be the most threatening in reducing the fatigue life of the joint. [Taken from abstract]. The full text is available in PDF format so Adobe Acrobat software is required in order to read it.

Assessment, Development, and Validation of Computational Fracture Mechanics Methodologies and Tools for Shot-Peened Materials Used in Rotorcraft Principal Structural Elements

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA AR-03/76 by S. Shen, Z. D. Han, C. A. Herrera, and S. N. Atluri dated July 2004. This report describes an analytical model that simulates the shot-peening process and estimates the residual stress field in the surface layer. A numerical approach for the prediction of crack growth rates for cracks in compressive stress fields was implemented in AGILE 3D. AGILE 3D is an accurate and efficient tool for predicting nonplanar three-dimensional (3D) fatigue crack growth in structural components. The results of validation of AGILE 3D for predicting 3D fatigue growth, compared to the University of Washington test data, were very good. The effect of shot peening on crack growth rates of various materials is investigated numerically by means of AGILE 3D. Various fatigue crack growth models, including plastic strip model and plastic zone model in the presence of residual stresses and plasticity, are discussed. [Taken from abstract]. The full text of the report is available in PDF format from the online catalogue of the FAA William J Hughes Technical Center Library.

Boundary Correction Factors for Elliptic Surface Cracks Emanating From Countersunk Rivet Holes Under Tension, Bending, and Wedge Loading Conditions : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-98/37, by Anisur Rahman and others, dated March 1999. The report focuses on the calculation of stress-intensity factor (SIF) solutions for cracks at countersunk rivet holes for tension, bending and wedge load conditions. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Bulging Factor Solutions for Cracks in Longitudinal Lap Joints of Pressurized Aircraft Fuselages

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA AR-04/2 by Anisur Rahman, John Bakuckas, Jr., and Catherine Bigelow dated June 2004. This report is a compilation of bulging factor solutions obtained at the Federal Aviation Administration William J. Hughes Technical Center for cracks in typical transport category aircraft. The solutions were obtained for longitudinal cracks in the critical rivet row of longitudinal lap splice joints. Both unstiffened and frame- and longeron-stiffened configurations were considered. The loading, crack length, skin thickness, substructure spacing, and properties were varied. Baseline solutions for cracks in an unstiffened shell were also obtained. The results from these studies are compiled in this report, and the effects of the parameters that were varied on the bulging factor are discussed. [Taken from abstract]. The full text is available in PDF format from the online catalogue of the FAA William J. Hughes Technical Center Library.

Central Aerohydrodynamic Institute (TsAGI)

The site provides information about one of the key Russian state aerospace research centers. Information on the site is arranged under a number of activity areas including; aerodynamics, flight dynamics, strength, hydrodynamics, measuements, and non-aerospace activities. The site provides general information about the Institute including a brief history and image gallery. The Institute's test facilities are described, a list of staff publications and news and contacts sections.

Characterization of In-Plane, Shear-Loaded Adhesive Lap Joints - Experiments and Analysis : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-03/21, by John Tomblin, Waruna Seneviratne, Hyonny Kim and Jungmin Lee, dated May 2003. In this experimental investigation, failure strengths of in-plane, shear-loaded bonded joints were compared with analytical predictions of the Shear-Loaded Bonded Joint (SLBJ) theory. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Civil Aviation Authority : Safety Regulation Group : Research Programme 2003/2004

This document contains details of projects that are managed by the UK Civil Aviation Authority (CAA) Safety Regulation Groupo (SRG). The projects are presented under sub-headings which, largely, correspond with technology areas within SRG. An appendix contains projects with which SRG are either associated or interested in but which are being carried out by other organisations. The document also lists the reports and papers produced during the period April 2002 to March 2003 as a result of SRG funded or managed work. The text of the document is available in PDF (2.8 Mb)format.

Comparison of Boundary Correction Factor Solutions for Two Symmetric Cracks in a Straight-Shank Hole : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-98/36, by John G. Bakuckas Jr., dated April 1999. The report compares the mode I boundary correction factor solutions for two symmetric elliptical cracks emanating from a straight-shank hole. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Composite Repair of Military Aircraft Structures

This is Research and Technology Organization (RTO) AGARD-CP-550 , dated January 1995. The AGARD Structures and Materials Panel held a specialists' Meeting to address composite repair of military aircraft. The meeting focused on two main areas, repair of metal structures using composite patches and repair of composite structures using composite or metal patches. The work presented had direct application to the maintenance and support of military aircraft. Repair of military aircraft provides both a means to extend the useful life of the airframe beyond the original design life and a method to maintain military readiness by returning damaged aircraft to service. For individual titles, see N95-27505 through N95-27528. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (58.6MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Computational Aeroelastic Analysis of Aircraft Wings Including Geometry Nonlinearity

This is a University of Cincinnati, Department of Aerospace and Engineering Mechanics PhD thesis, by Binyu Tian, 2003. The objective of the study is to show the ability of solving fluid structural interaction problems more realistically by including the geometric nonlinearity of the structure so that the aeroelastic analysis can be extended into the onset of flutter, or in the post flutter regime. A nonlinear Finite Element Analysis software is developed based on second Piola-Kirchhoff stress and Green-Lagrange strain. The nonlinear Finite Element Analysis software developed in this study is verified with ANSYS, NASTRAN, ABAQUS, and IDEAS for the linear static, nonlinear static, linear dynamic and nonlinear dynamic structural solutions. To solve the flow problems by Euler/Navier equations, the current nonlinear structural software is then embedded into ENSAERO, which is an aeroelastic analysis software package developed at NASA Ames Research Center. The aeroelastic analysis results have been obtained for fight wing in the transonic regime for various cases. The influence dynamic pressure on flutter has been checked for a range of Mach numbers. Bibliographic and abstract details are available in HTML and the full text of the document is accessible online in PDF format (27.62 Mb). This title is part of the OhioLINK Electronic Theses and Dissertations (ETD) Service

Computational Investigation of Aeromechanical HCF Effects in a Compressor Rotor

The site provides access to an Air University, Air Force Institute of Technology, Graduate School of Engineering and Management, MSc Thesis, by 2Lt Andrew L. White, USAF, AFIT/GA/ENY/01M-09, dated March 2001. The thesis describes the use of a three-dimensional Navier-Stokes programme to perform a study of the unsteady aerodynamics on a compressor rotor. The high-cycle fatigue effects of detuning were investigated by examining the unsteady forces and moments on the rotor blades and inlet guide vanes. Citation details and an abstract are available in HTML format. The full text can be accessed in PDF format. The document is part of the Air University Research Database.

Cooperative creep testing programme

This is Research and Technology Organization (RTO) AGARD-R-581, dated March 1971. Creep testing at elevated temperatures is an expensive and time-consuming business. Nevertheless, creep tests are frequently duplicated, there appears to be little confidence in creep data obtained from other laboratories. The AGARD Working Group on High-Temperature Material Testing was established in 1966 with the aim of improving the specifications and raising the standard of determination of the mechanical properties of materials at high temperatures in the NATO countries. This report describes the results accomplished. The results of creep and creep rupture measurements are subject to seemingly wide scatter. The major contributing factors have generally been qualitatively related to inhomogeneity of commercial materials and to inherent or inadequately controlled testing techniques and instrumentation. The latter sources of variability may be lessened by improved design of equipment and by improved specifications. The problem is of primary importance to metallurgists involved in the development of new materials, and also, to design engineers. Time and again creep laboratories are getting involved in interlaboratory evaluations of data either on the basis of private initiatives or within the framework of national or international cooperative programmes. During the preliminary discussions of the Working Group on High Temperature Testing of the Structures and Materials Panel of AGARD, it appeared that the implementation of a programme involving testing conditions currently encountered in superalloy technology, would be desirable. In summary, the objectives of the programme may be outlined as follows: (a) the comparison of creep and stress rupture data from different laboratories (b) the determination or estimation of relevant standard deviations (c) the evaluation of the adequacy of current specifications and testing techniques (d) the identification of possible significant sources of variability for further investigation (e) the establishment of a standard lot of material for use within laboratories in NATO countries (f) the determination for the material used of statistically significant creep data. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (11.85MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Corrosion and Corrosion Fatigue of Airframe Materials : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-00/22, by Robert P. Wei, dated July 2000. The report shows how localized pitting corrosion acts as crack nuclei and causes early crack nucleation and the onset of fatigue crack growth. A simplified probability model is presented, and this is used to demonstrate the feasibility of translating laboratory data into predictions of the evolution and distribution of damage of aircraft in service. The full text of the report is available in PDF format from the online catalogue of the FAA William J. Hughes Technical Center Library.

Corrosion and Fatigue Assessment of Aircraft Pressure Cabin Longitudinal Lap Splices

This technical report (NLR-TP-1999-408) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 1999 and was written by R. J. H. Wanhill. Because aircraft structures are susceptible to corrosion and fatigue damage, which concentrate at joints, there is a possibility of interactions between corrosion and fatigue, especially as aircraft become older. Of particular concern are the longitudinal lap splices of transport aircraft pressure cabins. This paper reports on the disassembly and investigation of lap splices from several types of transport aircraft. Broadly speaking, the investigation showed that pressure cabin longitudinal lap splices have a corrosion problem or a fatigue problem: severe corrosion does not result in Multiple Site Damage (MSD) fatigue cracking, and MSD is not initiated by corrosion. However, there is evidence of a mild environmental effect on MSD fatigue crack growth. The results are discussed with respect to MSD fatigue modelling and simulation and lap splice fatigue analysis methods. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software is required in order to read it.

Corrosion detection and management of advanced airframe materials

This is Research and Technology Organization (RTO) AGARD-CP-565, dated January 1995. A Specialists' Meeting on Corrosion Detection and Management of Advanced Airframe Materials was held to present the current knowledge base of corrosion, degradation, detection and prevention and to identify the research and development issues which must be addressed in order to ensure long service life and low maintenance costs of NATO aircraft. The Meeting concentrated on corrosion detection, test methodology for environmental assessment, mechanistic evaluation, corrosion prevention methods, and materials selection and design to prevent environmental degradation. For individual titles, see N95-23497 through N95-23519. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (47.32 MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Crack Growth-Based Predictive Methodologies for the Maintenance of Structural Integrity of Repaired and Nonrepaired Aging Engine Stationary Components : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/117, by George S. Hirko, Robert W. Hatala, and Robert A. Mattern, dated January 2003. This report contains the results of work conducted by Pratt & Whitney between October 1994 and January 2001 under the Federal Aviation Administration contract to study the effect of aging on stationary engine components. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Cranfield University Aerospace

Cranfield has been at the forefront of the development of aerospace technology for 60 years and is one of the largest academic centres in western Europe for strategic applied research, development and design. Cranfield University Aerospace brings together the University’s aerospace capabilities from all its five Schools into areas of strategic importance for its clients, within the aerospace and aviation markets. It consists of the following technology areas: flow control and prediction, computer integrated design, air transport management, human factors, avionics and simulation, structures and materials, air vehicle technology, flight test and dynamics and astronautics and space engineering. The site details Cranfield University Aerospace's capabilities, courses and current projects.

Crashworthiness Research at NLR (1990 - 2003)

This technical report (NLR-TP-2003-317) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2004 and was written by J.F.M. Wiggenraad. In the past decade, NLR has carried out research and development activities in several areas to improve the crashworthiness of future helicopters and fixed-wing aircraft. The crashworthiness of composite helicopters has been studied, and components for the NH90 helicopter have been developed. In several international collaborations, NLR has been involved in the development of crashworthy composite and metal aircraft structures. The potential for further improvements is expected to incite continuing collaborative research and development. [Taken from abstract]. The full text is available as a PDF file.

Damage Tolerance Characterization of Sandwich Composites Using Response Surfaces : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/101, by T.E.Lacy, I.K.Samarah, and J.S.Tomblin, dated November 2002. The influence of material configuration and impact parameters on the damage tolerance characteristics of sandwich composites comprised of carbon-epoxy woven fabric facesheets and Nomex honeycomb cores was investigated using empirically based response surfaces. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Delft Aerospace

This is the web site of the Faculty of Aerospace Engineering, Delft University. It describes the various educational programmes on offer along with supporting course information. There is also information on the various research groups, facilities, support services, student organisations as well as the Delft Aerospace Alumni Society. Other sections of the site include news and events, and a database of staff contact information.

Delphion Patent Search Form

This site allows you to search for United States patents, European patents and patent applications, Patent Cooperation Treaty (PCT) application data from the World Intellectual Property Office, the Patent Abstracts of Japan and INPADOC data. The service can be searched in several different ways, including patent number, US classification and Boolean keyword search. It is possible to view to the bibliographic information of granted US patents free of charge, all other services are payable. You will need to register to use this service, which is free of charge.

Department of Aeronautics at the Imperial College of Science, Technology and Medicine

The Web Site provides information on all major activities which are carried out by the Department, including teaching programmes, research and Departmental facilities, as well as the Departmental Staff. It contains information about the eight research groups - the Biomedical Flows Group, the Bluff Bodies and Vortex Flow Group, the Hypersonics Research Group, the Turbulence Mixing and Flow Control Group, the Spectral/hp Element Methods Group, the Geophysical Fluid Dynamics Group, the Turbulent Flow Modelling Group and the Flow Control Group. There are also links through to information about the Centre for Composite Materials within the department and the Honda Wind Tunnel. Details of undergraduate and postgraduate courses, short courses and research seminars are also provided.

Department of Aerospace Engineering at the University of Bristol

Part of the Faculty of Engineering, the Department of Aerospace Engineering at the University of Bristol has research interests in the areas of fluid flow and aerodynamics, thermo-fluid dynamics, dynamics and control systems, structures and materials, and space engineering. The site contains a description of the research activities of the department and information about staff, as well as available courses. The site also provide access to an article written by Sir Robert Wall which looks back over the University�s contribution to the first 100 years of manned flight.

Design, Manufacturing, and Performance of Stitched Stiffened Composite Panels With and Without Impact Damage : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/111, by H. Thomas Hahn, Jenn Ming Yang, Sung S. Suh, and Nanlin Han, dated October 2002. The goal of this project was to develop the knowledge base required for certification of composite structures in air transportation systems in the form of a design-manufacturing-performance relationship. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Detection of Stress Buildup in Airframes

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA/AR-03/71 by Dr. P.A. Stampe, Dr. R. J. Kennedy, and Dr. W.P. Tucker dated August 2004. This exploratory study investigates the role of texture development during fatigue cycling on crack initiation in airframes. The presence of texture in metals is known to relate to fatigue and the initiation of cracks. It has not been conclusively demonstrated, however, that texture will develop in a material simply due to cyclic fatigue. In this study, the development of texture during fatigue cycling of rolled aluminum 2024-T3 sheet was monitored using x-ray diffraction techniques. The texture development was calculated as a function of number of fatigue cycles (1) to determine whether texture changes as a material is fatigued and (2) to correlate the development of texture to crack formation. X-ray diffraction measurements show that the rolling direction initially lies normal to the preferred plane on which grains are oriented. In Millers indices, the rolling direction and the normal plane are denoted as [100] and (100) respectively. Upon fatigue cycling, an initially rapid development of texture is found to occur. Prior to cracking, the grains rotate such that the [100] direction lies along the stress axis. The rate of texture development is dependent on the direction of the strain axis with respect to the rolling direction of the aluminum and the number of cycles to failure. After crack initiation, the texture development slows down and changes gradually until the point of failure. This demonstrates that texture development does indeed occur with fatigue and plays a role in the development of cracks in the aluminum sheet. A more detailed study is required to develop a diagnostic test for proximity to crack initiation. [Taken from abstract]. The full text of the report is available in PDF format from the online cataligue of the FAA William J. Hughes Technical Center Library.

Development and Applications of a Flat Triangular Element for Thin Laminated Shells

This web page provides access to a Virginia Polytechnic Institute and State University Department of Aerospace and Ocean Engineering PhD dissertation, by P.Mohan, dated 18 November 1997. The thesis presents a finite element analysis of laminated shells using a three-noded flat triangular shell element. Several numerical examples are solved to demonstrate the accuracy of the formulation for both small and large rotation analysis of laminated plates and shells. Bibliographic and abstract details are available in HTML format. The full text of the document is accessible online in PDF format [3.93 Mb]. This title is part of Virginia Tech�s Electronic Thesis and Dissertation Collection (VT ETD)

Development and Validation of Advanced Test Methods to Generate Fatigue Crack Growth and Threshold Data for use in Damage Tolerance Analysis

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA/AR-04/22 written by Scott Forth, Mark James and William Johnston dated February 2008. This report describes the results of a research program that determined the damage tolerance properties of metallic propeller materials. Three alloys were selected for investigation: 2025-T6 aluminum alloy, D6AC steel, and 4340 steel. Mechanical response, fatigue stress life, and fatigue crack growth rate data are presented for all the alloys. The mechanical response can be characterized using tensile tests per American Standard Test Method (ASTM) E 8. This data was used to compute yield and ultimate stresses and the elastic modulus that can be used in damage tolerance analysis tools. Fatigue testing allowed the manufacturers to verify the integrity of their in-house data and determine if material or manufacturing changes over the past years have altered the response of the material. Furthermore, this data can be used to determine an equivalent initial flaw size if the designer wishes to relate stress-life results to damage tolerance. Most importantly, the fatigue crack growth rate response of the material must be understood to predict the life of the structure from an initial detectable flaw and to set inspection intervals. This fatigue crack growth rate data was generated using ASTM E 647 and an alternative method using compression precracking. Alternative precracking methods were used to reduce load history effects when generating threshold data, producing material response data that was unaffected by the test method. {Taken from abstract]. The full text is available in PDF format so Adobe Acrobat is required in order to read it.

Development of a Crashworthy Composite Fuselage Concept for a Commuter Aircraft

This technical report (NLR-TP-2001-108) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2001 and was written by J. F. M. Wiggenraad, D. Santoro, F. Lepage, C. Kindervater and H. Climent Manez. Within the framework of Brite-Euram programme CRASURV "Commercial Aircraft - Design for Crash Survivability", technology was developed for the design of composite air frames with respect to crashworthiness. The ultimate goal of the project was to develop computer codes for the simulation of the crash behaviour of composite fuselage structures. A significant part of the project consisted of the design, fabrication and droptesting of two representative composite fuselage sections, to generate the experimental data needed for the validation of the new code developments. The present paper gives an overview of the development, test and numerical analysis of one of the fuselage sections, a one-bay section representative of a commuter aircraft like the ATR-42/72. The fuselage section consists of the sub-floor structure, which is the major area that will be crushed during a potentially survivable crash. The structure failed in a mode which was not predicted. The deficiencies of the model were repaired and a post-test analysis gave satisfactory results. The project has resulted in improved simulation capabilities. However, it cannot be concluded that the state-of-the-art is such, that the behaviour of new composite structures can be predicted accurately in the near future. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Development of an Analysis and Design Environment for Hybrid Damping

This technical report (NLR-TP-2000-029) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2000 and was written by A. de Boer, R.P.G. Veul, P. Arendsen and M. Bakker. Vibration reduction by adding damping to the structure is mostly carried out when the structure has been built. The fast developments in computer technology makes it possible that more complex analyses in which damping is included can be applied in the design process. At NLR research is carried out on the integration of advanced analysis tools in design environments. In this paper the tools developed for the analysis of passive and active damping in structures is presented. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Documentation of the Linear Statistical Discrete Gust Method

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA AR-04/20 by J.G. Jones dated July 2004. The Statistical Discrete Gust (SDG) method is an alternate procedure for estimating and predicting severe gust and severe turbulence loads. This method claims to have the potential to replace the combined Power Spectral Density (PSD) Model of Title 14 Code of Federal Regulations (CFR) 25.341(b) and the Tuned Isolated Discrete Gust (IDG) of 14 CFR 25.341(a), which jointly ensures that an airplane has sufficient structural strength for encounters with continuous turbulence (PSD) and discrete gusts (TDG) of design-level intensity. The SDG method provides such a specification in a form that takes into account the non-Gaussian statistical structure of the more intense turbulence fluctuations and the manner in which these interact with the dynamic response of a flexible aircraft. This report documents the development of the method, as applied to the response of a linear aircraft, in the following order: historical development, evidence that severe and extreme gust encounters are characterized by short-duration bursts evidence for the 1/6 scaling law examples of calculated loads and comparisons with models in existing requirements, and advantages and limitations of current SDG models. The SDG method was developed over a period of over 30 years, and during its development, many in industry, research institutions, and academia have expressed divergent viewpoints regarding the suitability of using the SDG method for the derivation of design gust loads. Consequently, the Federal Aviation Administration has invited three experts to express their views and comments, which have been included as an addendum in the documentation of the SDG method contained herein. [Taken from abstract]. The full text of the report is available in PDF format from the online catalogue of the FAA William J. Hughes Technical Center Library.

Documentation of the Linear Statistical Discrete Gust Method

This provides access to a Federal Aviation Administration (FAA) report SDI-121-TR-1 by J. G. Jones dated July 2004. The Statistical Discrete Gust (SDG) method is an alternate procedure for estimating and predicting severe gust and severe turbulence loads. This method claims to have the potential to replace the combined Power Spectral Density (PSD) Model of Title 14 Code of Federal Regulations (CFR) 25.341(b) and the Tuned Isolated Discrete Gust (IDG) of 14 CFR 25.341(a), which jointly ensures that an airplane has sufficient structural strength for encounters with continuous turbulence (PSD) and discrete gusts (TDG) of design-level intensity. The SDG method provides such a specification in a form that takes into account the non-Gaussian statistical structure of the more intense turbulence fluctuations and the manner in which these interact with the dynamic response of a flexible aircraft. This report documents the development of the method, as applied to the response of a linear aircraft, in the following order: historical development, evidence that severe and extreme gust encounters are characterized by short-duration bursts evidence for the 1/6 scaling law examples of calculated loads and comparisons with models in existing requirements, and advantages and limitations of current SDG models. The SDG method was developed over a period of over 30 years, and during its development, many in industry, research institutions, and academia have expressed divergent viewpoints regarding the suitability of using the SDG method for the derivation of design gust loads. Consequently, the Federal Aviation Administration has invited three experts to express their views and comments, which have been included as an addendum in the documentation of the SDG method contained herein. [Taken from abstract]. The full text of the report is available in PDF format from the online catalogue of the William J.Hughes Technical Center Library.

Effective Global Transportation in the Twenty-First Century : A Vision Document

This web site provides access to the text of a vision document prepared by the US Department of Transportation's "ONE DOT" Working Group on Enabling Research, dated September 1999. It presents a vision of what a future transportation system might look like in the period around 2020; and suggests some possible directions that transportation might take in the 10-20 years thereafter. The text is available online in HTML format. The resource is part of the web site of the John A. Volpe National Transportation Systems Center.

Efficient Methods for Structural Analysis of Built-Up Wings

This web site provides access to a Virginia Polytechnic Institute and State University Department of Aerospace and Ocean Engineering PhD dissertation, by Youhua Liu, dated 28 April 2000. The thesis describes the development and testing of a number of methods for studying the static and free-vibration problems of built-up wing structures composed of skins, spars, and ribs. These include Equivalent Plate Analysis, EPA with indirect application of Neural Networks (called an Equivalent Skin Analysis), as well as Sensitivity Techniques. Bibliographic and abstract details are available in HTML format. The full text of the document is accessible online in PDF format [6.69 Mb]. This title is part of Virginia Tech�s Electronic Thesis and Dissertation Collection (VT ETD).

Engine Debris Fuselage Penetration Testing Phase 1 : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-01/27, by Steven J. Lundin dated August 2001. The document presents the results of a series of simulated uncontained engine failure structural impact tests. The full text of the report is available in PDF format.

Enhanced Crack Detection by Combination of Laser and Ultrasonic Techniques

This web site provides access to a University of Cincinnati, Department of Aerospace Engineering and Engineering Mechanics PhD dissertation, by Zhongyu Yan, dated 2001. It examines two methods of enhancing the detection of fatigue cracks using pulsed laser irradiation. Bibliographic and abstract details are available in HTML format. The title page, contents and the full text of the document are accessible online in PDF format (1.87 MB). This title is part of the OhioLink Electronic Theses and Dissertations Project.

Enhancing Aircraft Survivability: A Vulnerability Perspective Conference

The site contains full-text papers and presentations from a conference sponsored by the National Defense Industrial Association, dated October 21 - 23 1997, Naval Postgraduate School, Monterey, CA. The various contributions cover a range of military and commercial topics related to vulnerability and survivability. These include for example, fire safety, structural design issues, aviation security, and orbital debris penetration. Access to the conference presentations is provided by the US Defence Technical Information Center. The files are in Adobe Acrobat 3.0 format.

Erosion, Corrosion and Foreign Object Damage Effects in Gas Turbines

This is Research and Technology Organization (RTO) AGARD-CP-558, dated November 1994. The Conference Proceedings contains 31 papers presented at the Propulsion and Energetics Panel Symposium on Erosion, Corrosion and Foreign Object Damage Effects in Gas Turbines which was held from 25-28th April 1994, in Rotterdam, The Netherlands. The Technical Evaluation Report and the Keynote Address are included at the beginning and discussions follow most papers. The Symposium was arranged in the following Sessions: Operational Experience and Requirements (7); Deposition and Erosion (7); Foreign Object Damage (5); Coatings, Repairs and Materials Aspects - 1 (4); Coatings, Repairs and Materials Aspects - 2 (7); and Testing and Certification Procedures (1). For individual titles, see N95-19654 through N95-19684. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (85.83MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

ESDU International

ESDU create and maintain over 22 series of validated engineering design data covering structural, mechanical, aeronautical and chemical process engineering. They are produced by committees of independent experts who ensure that each Data Item is a sound technical document which presents a clear explanation of the recommended approach. The bulletins that each committee produce are available for viewing using Adobe Acrobat. Subscribers to the service can access the full text of all data items. Non subscribers may view abstracts of each Data Item. An FAQ, glossary and technical notes are also available.

European Aeronautics Science Network (EASN)

This is a three year funded project which aims to bring the European universities with aeronautics activities into an integrated network, operating in parallel with industry and the national research establishments. EASN has a Steering Committee representing partners to oversee the activities of the network, as well as a number of Interest Groups (IGs) addressing various thematic issues. There are 10 interest areas covering Flight Physics, Aerostructures, Propulsion, Aircraft Avionics Systems and Equipment, Flight Mechanics, Integrated Design and Validation, Air Traffic Management, Airports, Human Factors, and Innovative Concepts and Scenarios. Within these areas several Interest Groups have been established for Advanced Combustion Chambers, Ageing Aircraft, Crashworthiness and Structural Impact, Emission Minimizing Flight Operations, Fault Tolerant Systems, Increased Exploitation of Composites, Manufacturing Processes and Technologies of Aero-Engines, Risk Analysis Based LCE in Aeronautics, Surface Engineering Treatments, Vortical Structures and IG Innovative Contacts and Scenarios. The central element is an open, Internet based network that will enable communication between groups and will provide access to a database. The Network Database contains Information on the university institutes with their aerospace competence profiles, companies and organisations in the aerospace supply chain, research establishments and information on national aeronautics research programmes. The web site describes the network members and provides details of each of the regional contact points. It identifies R&T areas and Interest Groups and the Universities who are engaged in research activities in these areas. The site also provides news and a list of related links.

Evaluation of the SPH Method for the Modelling of Spall in Anisotropic Alloys

This paper was given at the 5th Dynamics and Control of Systems and Structures in Space (DCSSS) conference by Tom De Vuyst, Rade Vignjevic, Neil K. Bourne and James Campbell. The conference took place in July 2002 at King's College, Cambridge. Spall caused by hypervelocity impacts at the lower range of velocities could result in significant damage to spacecraft. A number of polycrystalline alloys, used in spacecraft manufacturing, exhibit a pronounced anisotropy in their mechanical properties. The aluminium alloy AA 7010, whose orthotropy is a consequence of the meso-scale phase distribution or grain morphology, has been chosen for this investigation. The material failure observed in plate impact was simulated using an explicit finite element code and a smoothed particle hydrodynamics (SPH) code. A number of spall models where used, and the Hugoniot Elastic Limit (HEL) and spall strength have been studied as a function of orientation, and compared to experimental results. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software is required in order to read it.

Evaluation Techniques for Determining Damping Mechanisms on Titanium Plates

This is the full text of a Master's thesis by Lieutenant Kyle S. Allen, USAF, AFIT/GAE/ENY/05-M01, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2005. High cycle fatigue (HCF) is the single largest cause of component failure for all modern military gas turbine engines. Hard coatings, such as magnesium aluminate spinel, have been found to provide significant damping properties. Past studies have had difficulties isolating the contributions of these hard coating damping layers from other damping mechanisms. This study explored techniques for assessing the contribution of different damping mechanisms on titanium plates during vibration testing. The study investigated 2nd bend and 2-stripe modes. Two different specimen sizes were tested in both a clamped-free-free-free and free-free-free-free condition. Specimens were tested at varying pressures. Increases in pressure caused linear peak modal frequency downshifts for both modes of interest for both specimen sizes, and for both boundary conditions. Increases in damping were also seen with increases in pressure for bare plates for the two-stripe mode for both boundary conditions. The clamped boundary condition contributions on the system damping were also investigated. Increases in the stiffness of the cantilevered clamp in the clamped-free-free-free condition were shown to have limited affect on plate damping. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

Extension of Viscoplasticity Based on Overstress to Capture the Effects of Prior Aging on the Time Dependent Deformation Behavior of a High-Temperature Polymer: Experiments and Modeling

This is the full text of a thesis written by Amber McClung which was presented to the Air Force Institute of Technology, Wright Patterson Air Force Base, Ohio, in October 2008. The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at 288 degrees C. The experimental program was designed to explore the influence of strain rate on tensile loading, unloading, and strain recovery behaviors. In addition, the effect of the prior strain rate on the relaxation response of the material, as well as on the creep behavior following strain controlled loading were examined. The experimental data were modeled with the Viscoplasticity Based on Overstress (VBO) theory. A systematic procedure for determining model parameters was developed and the model was employed to predict the response of the material under various test histories. Additionally the effects of prior aging at 288 degrees C in argon on the time (rate)-dependent behavior of the PMR-15 polymer were evaluated in a series of strain and load controlled experiments. Based on experimental results, the VBO theory was extended to capture the environmentally induced changes in the material response. Several of the VBO material parameters were expanded as functions of prior aging time. The resulting model was used to predict the high-temperature behavior of the PMR-15 polymer subjected to prior aging of various durations. [Taken from Abstract]. This is in PDF format so Adobe Acrobat software is required in order to read it.

Extreme value analysis and its application to c.g. vertical accelerations measured on transport airplanes of type C-130

This is Research and Technology Organization (RTO) AGARD-R-579, dated March 1971. The interpretation of cumulative frequency distributions of measured flight loads can be increased significantly by an additional extreme value analysis. This method not only leads to a higher reliability in fatigue design but may be used also for a prediction of extreme loading conditions and for a description of the effect of airplane and flight parameters on loads, as is demonstrated for c.g. vertical accelerations and gust velocities measured on airplanes o f / t ype C-130. This report is a sequel to a paper presented by Dr.O.Buxbaum on 5th November 1970 at the 31st'meeting of the Structures and Materials Panel in Tdnsberg, Norway. In this paper, Dr.Bauxbaum, whose contribution to the study of statistics related to atmospheric turbulence has been particularly fruitful, attacks a problem of considerable importance to both civilian and military aeronautical industry: the prediction of the extreme loads which a structure must be able to withstand. The application of the model proposed by Dr.Buxbaum to measurements obtained on the C-130 aircraft provides an excellent confirmation of the method. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (7.86MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

FAA-NASA Symposium on the Continued Airworthiness of Aircraft Structures : Vol. 2

Compiled by Catherine A. Bigelow, these proceedings (DOT/FAA/AR-97/2) were published in July 1997 by the Federal Aviation Administration (FAA). This collection of papers on airworthiness of aircraft structures discusses airframe life extension through quantitative rework inspections, analysis of a composite repair, analytical fatigue life estimation of full-scale fuselage panels, and application of acoustic emissions (AE) to health monitoring of helicopter mechanical systems. This is a PDF file so Adobe Acrobat software will be required in order to read it.

Failure Modeling of Titanium 6A1-4V and Aluminum 2024-T3 with the Johnson-Cook Material Model

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA AR-03/57, by Gregory Kay, dated September 2003. Johnson-Cook failure strain parameters were developed for Ti-6Al-4V and 2024-T3 aluminum. The titanium parameters, obtained from simulations of split Hopkinson bar tensile tests, were successfully used to simulate blade fragment impact tests on 0.602., 0.250., and 0.737. thick titanium targets. Titanium failure parameters that were derived from scaled down ballistic limit testing produced a failure envelope which was not suitable for use on full-scale tests. 2024-T3 aluminum failure parameters were obtained from simulations of one-third-scale ballistic limit test results. The aluminum failure parameters were used to simulate three blade fragment impact tests against a commercial transport aircraft fuselage. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Fatigue in the Presence of Corrosion

This web site provides access to a NATO Research and Technology Organization (RTO) document titled: Fatigue in the Presence of Corrosion, RTO-MP-18, March 1999. This report contains 22 papers presented at the Workshop of the RTO Applied Vehicle Technology (AVT) Panel, held in Corfu, Greece, 7-8 October 1998. The four workshop sessions covered the following topics: In-service experience with corrosion fatigue; Simulation/Test evaluation programmes; Fatigue prediction methodologies in corrosive environments; and, Structural integrity - corrosion and fatigue interactions.

Flight Simulation Fatigue Crack Growth Guidelines

This technical report (NLR-TP-2001-545) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2001 and was written by R. J. H. Wanhill. Flight simulation fatigue crack growth tests are used to evaluate fatigue-critical areas and details in aerospace structures, compare candidate materials, joint designs and surface treatments, and provide data for checking crack growth prediction methods. However, such tests evoke complicating issues that need to be addressed by guidelines. This paper gives a number of guidelines obtained from NLR research on test specimens and, more recently, aircraft pressure cabins. [Taken from abstract]. The full text is available as a PDF file.

Frequency response functions and human pilot modelling

This is Research and Technology Organization (RTO) AGARD-R-580, dated March 1971. The Structures and Materials Panel of the NATO Advisory Group for Aerospace Research and Development (AGARD) comprises scientists, engineers and technical administrators, from industry, government and universities throughout NATO, concerned with advancing the status of aerospace research and development and with developing technical means and data for optimizing the vehicles and equipment of interest to NATO. The increasing complexity of modern aircraft arising from more stringent performance requirements - in terms of speed, range, altitude capability, manoeuvrability, etc. – have emphasized the critical importance of examining the inter-related facets of aircraft design and operation in a total, systems sense. The Panel, engaged through a number of cooperative projects in studying a variety of behaviour phenomena and establishing as solid a basis as possible for optimization of design and minimization of flight and structural problems, has been both aware of and concerned about these inter-relationships and, in a specific instance addressed itself to the question of interactions between handling qualities, static and dynamic stability, control and structural loads. In order to obtain a clearer picture of these interactions and their effects, it was decided that the state-of-the-art in transfer function (frequency response function) development should be assessed. This function ties together all the inter-related aspects of potential interactions between structural loads and the other subdisciplines of aeronautics. The following reports are one such result of the Panel decision. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (8.98MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Full-Scale Testing and Analysis of Fuselage Structure Containing Multiple Cracks : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-01/46, by John Bakuckas, dated July 2002. An experimental and analytical study was conducted to determine the effects of multiple cracks on the fatigue crack growth and residual strength of curved fuselage panels. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Gaseous Detonation-Driven Fracture of Tubes

This is a California Institute of Technology, Graduate Aeronautical Laboratories PhD dissertation, by Tong Wa Chao, submitted March 2004. An experimental investigation of fracture response of aluminum 6061-T6 tubes under internal gaseous detonation loading has been carried out. The pressure load, with speeds exceeding 2 km/s, can be characterized as a pressure peak (ranging from 2 to 6 MPa) followed by an expansion wave. The unique combination of this particular traveling load and tube geometry produced fracture data not available before in the open literature. Experimental data of this type are useful for studying the fluid-structure-fracture interaction and various crack curving and branching phenomena, and also for validation for multi-physics and multi-scale modeling. Axial surface flaws were introduced to control the crack initiation site. Fracture threshold models were developed by combining a static fracture model and an extensively studied dynamic amplification factor for tubes under internal traveling loads. Experiments were also performed on hydrostatically loaded preflawed aluminum 6061-T6 tubes for comparison. Significantly different fracture behavior was observed and the difference was explained by fluid dynamics and energy considerations. The experiments yielded comparison on crack speeds, strain, and pressure histories. In other experiments, the specimens were also pre-torqued to control the propagation direction of the cracks. Measurements were made on the detonation velocity, strain history, blast pressure from the crack opening, and crack speeds. The curved crack paths were digitized. The Chapman-Jouguet pressure, initial axial flaw length, and torsion level were varied to obtain different crack patterns. The incipient crack kinking angle was found to be consistent with fracture under mixed-mode loading. High-speed movies of the fracture events and blast wave were taken and these were used in interpreting the quantitative data. Numerical simulations were performed using the commercial explicit finite-element software LS-Dyna. The detonation wave was modeled as a traveling boundary load. Both non-fracturing linear elastic simulations and elastoplastic simulations with fracture were conducted on three-dimensional models. The simulated fracture was compared directly with an experiment with the same conditions. The overall qualitative fracture behavior was captured by the simulation. The forward and backward cracks were observed to branch in both the experiment and simulation. The full text of the document is accessible online in PDF format [9.41 Mb]. This title is part of California Institute of Technology's Electronic Thesis and Dissertation (ETD) Collection

Guidelines and Recommended Criteria for the Development of a Material Specification for Carbon Fiber/Epoxy Unidirectional Prepregs : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/109, by William McCarvill, Stephen Ward, Gregg Bogucki, and John Tomblin, dated March 2003. This report establishes recommendations to guide the development of composite prepreg material specifications to be used on aircraft structures.The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Guidelines for Analysis, Testing, and Nondestructive Inspection of Impact-Damaged Composite Sandwich Structures : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/121, by Peter Shyprykevich, J.Tomblin, and L.Ilcewicz, dated March 2003, In this report, past work is summarized and synthesized to provide guidance for analysis, testing, and nondestructive inspection of impact-damaged composite structures. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Guidelines for the Development of Process Specifications, Instructions, and Controls for the Fabrication of Fiber-Reinforced Polymer Composites : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/110, by Gregg Bogucki, William McCarvill, Stephen Ward, and John Tomblin, dated March 2003. This document provides (1) a set of guidelines for the development of process specifications for the fabrication of continuous fiber-reinforced polymer composite laminate test panels used in the generation of mechanical properties and (2) an approach for the validation of composite fabrication processes used during the certification of composite aircraft structure. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center library.

Handbook of brittle material design technology

This is Research and Technology Organization (RTO) AGARD-AG-152, dated February 1971. Interest in the structural use of brittle non-metallic refractory materials in aerospace vehicles arises as a result of interest in re-entry vehicles and the continuing need for propulsion systems of increased performance. In both of these situations performance is dependent on the temperature capability of the structural materials. The presence of temperatures beyond the capability of most metallic materials has encouraged designers to study “ceramics” but, with the possible exception of inserts in the throats of some solid rocket motors, significant applications have not developed. Characteristically these materials show no plastic deformation before failure at temperatures of interest, and they have little toughness to arrest crack growth. These characteristics have resulted in a lack of confidence by designers, in such materials, and unwillingness to use them. The materials to which this handbook is intended to apply include oxides, carbides, borides and similar compounds. Graphite, in its many forms, is also included. The important characteristic of these materials is refractoriness, which permits them to be used in applications where the more structurally efficient metals are useless. Such materials have been used extensively in the past for high temperature applications, such as furnace linings, but these have involved ground installations where weight was generally not important. Currently the interest involves the high temperature applications generated by re-entering space vehicles and rocket engine compounds, but since these are extremely weight critical applications, substantial improvements in structural efficiency and reliability over those typical of the furnace type application must be obtained. Among the applications which are of current interest for this class of material are numerous components for winged re-entry vehicles or hypersonic atmospheric vehicles, and these include leading edge elements, nose caps, surface panels, which may or may not include elements for insulation, control surface structural parts, and engine intake structural parts. Rocket engine nozzles and chambers are the obvious propulsion applications. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (76.36MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

High temperature cyclic behavior of aerospace materials: Room temperature validation tests of Ti-6Al-4V

This is Research and Technology Organization (RTO) AGARD-AR-328, dated June 1994. Materials specification and distribution of Ti-6Al-4V specimens are presented along with the collated data from those participants that have supplied test results. Crack propagation and strain control low cycle fatigue data are discussed, along with a number of points of clarification regarding test technique. This report, sponsored by the Structures and Materials Panel of AGARD, contains all relevant information on the validation exercise conducted by participants of Working Group 26. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (6.52MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Impact Damage Characterization and Damage Tolerance of Composite Sandwich Airframe Structures : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-00/44, by John S. Tomblin et al, dated January 2001. The report describes the results of damage tolerance experiments on sandwich panels conducted at Wichita State University. The effect of impactor size on impact resistance and residual strength was investigated. The effectiveness of traditional nondestructive inspection (NDI) methods for detecting and quantifying damage distribution in sandwich panels was also studied and the salient results are presented. The full text of the report is available in PDF format.

Impact Damage Characterization and Damage Tolerance of Composite Sandwich Airframe Structures � Phase II : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/80, by Tomblin, John S., Raju, K.S., Acosta, J.F., Smith, B.L., and Romine, N.A. dated October 2002. The impact responses and the damage states in flat composite sandwich panels with thin facesheets were investigated in Phase I and were found to be dependent on the diameter of the spherical steel impactor. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Impact of Acoustic Loads on Aircraft Structures

This is Research and Technology Organization (RTO) AGARD-CP-549, dated September 1994. A broad band of different activities was addressed in the Specialists' Meeting held by the Structures and Materials Panel of AGARD in May 1. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (152.88MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Impact of Materials Defects on Engine Structures Integrity

This is Research and Technology Organization (RTO) AGARD-R-790 , dated April 1993. Engine failures due to materials defects are rare, but are still a cause for concern to both manufacturers and lifting authorities. In these circumstances it is recognized that the introduction of higher strength materials, new production routes and improved non-destructive evaluation methods may have significant implications for engine lifing and safety. The impact of inherent defects on present and future component manufacture and on aircraft engine operation is considered. Materials processing and control aspects are reviewed, placing particular emphasis on nickel and titanium engine disc materials. Variations in engineers', scientists' and lawyers' interpretation of the work 'defect' was perhaps the most significant point to emerge from the meeting; so much so, that a small group agreed to develop a definition, and when established recommend it as standard AGARD materials technology. For individual titles, see N94-37322 through N94-37331. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (28.07 MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Impact of Parameter Accuracy on Aircraft Structural Integrity Estimates

The site provides access to an Air University Air Command and Staff College Research Report, by Major Scott A. Fawaz, USAF, AU/ACSC/048/2001-04, dated April 2001. The purpose of this research was to investigate the sensitivity of fatigue life estimates on the parameters used to generate the estimate. Nine linear elastic fracture mechanics (LEFM) parameters are identified that affect the fatigue life. These are initial flaw assumption, boundary correction factor, load interaction models, crack growth rate data, stress intensity factor, threshold stress intensity factor, yield stress, and critical stress intensity factor. The parameters are classified as primary or secondary based on their effect on the life cycle costs, inspection schedule, and flight safety. Citation and abstract details are provided in HTML format, and the full text is available for downloading as a PDF file. This is one of the collection student research studies available from Air University's Research Web.

Implications of Emerging Micro and Nanotechnology

This is a report prepared by the National Research Council's Committee on Implications of Emerging Micro- and Nanotechnologies, Air Force Science and Technology Board, published Washington, DC, National Academy Press, December 2002. Expansion of micro-technology applications and rapid advances in nano-science have generated considerable interest by the United States Air Force in how these developments will affect the nature of warfare and how it could exploit these trends. The report notes four principal themes emerging from the current technological trends: increased information capability, miniaturization, new materials, and increased functionality. Recommendations about Air Force roles in micro- and nanotechnology research are presented including those areas in which the Air Force should take the lead. The report also provides a number of technical and policy findings and recommendations that are critical for effective development of the Air Force�s micro- and nano-science and technology programme. Bibliographic and abstract information is available in HTML format, access to the full text is provided online in Open Book format with printable PDF files, and an abridged reports version is also available in PDF format.

Improved Barriers to Turbine Engine Fragments : Interim Report I

This web site provides access to a Federal Aviation Administration Report titled: Improved Barriers to Turbine Engine Fragments: Interim Report I, by D.A. Shockey, Jeffrey W. Simmons and David C. Elrich, DOT/FAA/AR-99/8, June 1999. This is the first part of a report produced by SRI International's Poulter Laboratory on behalf of the FAA, which examines the ballistic performance of various barriers of Zylon (polybenzoxazole, PBO) fabric, in gas gun tests using fragment simulating projectiles. The framework of a fabric model was constructed and simple impacts were simulated to demonstrate efficacy. The full text of the report is available in PDF [10.0 Mb] format from the online catalogue of the FAA William J. Hughes Technical Center Library.

Improved Barriers to Turbine Engine Fragments : Interim Report II

This web site provides access to a Federal Aviation Administration (FAA) Report titled: Improved Barriers to Turbine Engine Fragments: Interim Report II, by D.A. Shockey, Jeffrey W. Simmons and David C. Erlich, DOT/FAA/AR-99/8, II, May 1999. The is the second part of a report produced by SRI International's Poulter Laboratory on behalf of the FAA, which evaluates the ballistic effectiveness of fabric structures made from advanced polymers, and investigates the computational modeling of fragment barriers. The ballistic response of fabrics to fragment impact was evaluated, the phenomenology of fabric deformation and failure was elucidated in quasi-static penetration tests, and the tensile properties of yarns and fibers were measured. The full text of the report is available in PDF [1.2 Mb] format from the online catalogue of the FAA William J. Hughes Technical Center Library.

Improved Barriers to Turbine Engine Fragments : Interim Report III

This web site provides access to a Federal Aviation Administration (FAA) Report, by D.A. Shockey, David C. Elrich, and Jeffrey W. Simmons, DOT/FAA/AR-99/8, III, May 2001. The report describes the development of a mathematical model to assist the efficient design of fabric fragment barriers. The model was used to simulate the failure behaviour of yarns and fabrics under impact scenarios. The full text of the report is available online in PDF format.

Including Fatigue Aspects in Balance Design

This technical report (NLR-TP-2004-198) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2004 and was written by H. B. Vos. Several high load balance systems have been designed and manufactured in recent years. Some systems failed after intensive use. A review of the complete balance development chain, from specification to tunnel use has been performed, and influential factors have been identified. Better fatigue analysis is possible and necessary, based on a more accurate load specification. For balances which will endure a highly unpredictable load spectrum, a fatigue monitoring system is necessary. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software is required in order to read it.

Inspection Of Composite Compressed Gas Cylinders : Final Report

This report was prepared by Mark Toughiry and Chris Coughlin, on behalf of Research and United States Department of Transportation, Special Programs Administration, September 2002. The report describes the result of a study carried out by The Nondestructive Testing Information Analysis Center (NTIAC), to identify a reliable and quantifiable NDE method for inspection and recertification of composite high pressure gas cylinders. The text of the report is available in PDF format.

Institute for Aerospace Research

The Institute for Aerospace Research (IAR) is Canada's national aerospace laboratory. This site provides a range of introductory information which includes online access to the current strategic plan. The core content of the site is devoted to the four constituent IAR laboratories: Aerodynamics; Flight Research; Structures, Materials and Propulsion and Aerospace Manufacturing Technology. Each of these sections contain largely descriptive information on specific areas of research interest and expertise. The full-text of IAR Flyer, a newsletter, is also available online.

Integrated Airframe Design Technology

This is Research and Technology Organization (RTO) AGARD-R-794 , dated December 1993. Integrated airframe design embraces the concept of bringing together all of the aspects of airframe design, including various disciplines such as structures, materials, aerodynamics, controls, and manufacturing, from conceptual design all the way through manufacturing. It also includes the sub-disciplines which are involved in each discipline and the interactions these have with one another. Moreover, an IAD process also affects the organizational structure of the personnel. In order to provide a broad-based approach to evaluating and identifying future research and development directions required to provide IAD technology, the First Integrated Airframe Design Technology Workshop, sponsored by AGARD, was held in Antalya, Turkey on 19-20 Apr. 1993. This document summarizes the output of that Workshop. For individual titles, see N94-24314 through N94-24327. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (46.29MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

International Society of Allied Weight Engineers

The International Society of Allied Weight Engineers is a not-for-profit organisation, with a membership consisting of engineers associated with shipbuilding, land transportation and other allied industries and technologies. One of its primary goals is to promote recognition of mass properties engineering as a specialized discipline within the spectrum of professional engineering. The Site contains background information on SAWE and its chapter organisations. The site provides a complete listing of SAWE technical papers (ordering information - no full text), and details of SAWE recommended practices and relevant military standards (some full text.) The SAWE Newsletter is available online, and there is an archive of past issues. Other documents include the SAWE Operations Manual and table of contents of a textbook, Introduction to Aircraft Weight Engineering

Introduction of Ceramics into Aerospace Structural Composites

This is Research and Technology Organization (RTO) AGARD-R-795 , dated November 1993. Ceramics have been considered over the last two decades as a possible alternative to refractory metals and alloys to be used as structural materials for aeronautical use. The main disadvantage of these materials is their brittleness and the very low value of the critical size of defects leading to fracture. The concept of ceramic matrix composites has been recognized as one of the ways to escape this difficulty. Extensive work has been performed to identify the mechanisms of crack propagation and general fracture for unidirectional composites, laminates or other fabrics, including the understanding of their long term response: creep and fatigue effects or environmental degradation. The Workshop which has been held by AGARD SMP at Antalya (Turkey), April 1993, aimed at reviewing the present knowledge on all these aspects. For individual titles, see N94-24229 through N94-24240. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (47.65 MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Inventory of acoustic fatigue test facilities in the NATO countries

This is Research and Technology Organization (RTO) AGARD-R-584 , dated August 1971. This recent survey carried out by a small specialist group converted by B.L Clarkson, the AGARD Structures and Materials Panel Co-ordinator for Acoustic Fatigue, concluded that there is now active interest and significant work in acoustic fatigue in six of the NATO countries. As a result of this initial survey of interest, a collaborative programme of data collection and compilation has been proposed. Arrangements have been made for the Engineering Sciences Data Unit to undertake the collation of this data and the preparation of design data sheets. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (2.69MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Investigation of Large Strain Actuation in Barium Titanate

This is a California Institute of Technology, Graduate Aeronautical Laboratories PhD dissertation, by Eric Burcsu, defended 15 May, 2001. Descriptions of the phenomenological theories of ferroelectrics are presented including the classical Landau-Ginsburg-Devonshire theory and the more recent theory of Shu and Bhattacharya. Predictions are made, based on the theory, of the electromechanical behavior of ferroelectric crystals that are addressed by the experiments. An experimental setup has been designed to investigate large strain actuation in single crystal ferroelectrics based on combined electrical and mechanical loading. An investigation of the stress dependence of the electrostrictive response has been carried out with in situ observations of the domain patterns under constant compressive stress and variable electric field. Experiments have been performed on initially single domain crystals of barium titanate with (100) and (001) orientation at compressive stresses between 0 and 5 MPa. Global strain and polarization histories have been recorded. Polarized light microscopy has been used to observe the evolution of the domain pattern simultaneously with the strain and polarization measurement. These results are discussed and suggestions for future work are proposed. Bibliographic and abstract details are available in HTML format. The full text of the document is accessible online in PDF format [6.57 Mb]. This title is part of California Institute of Technology's Electronic Thesis and Dissertation (ETD) Collection

Italian Aerospace Research Centre

This is the homepage of the Italian Aerospace Research Centre (CIRA), a non-profit making research consortium which carries out the Italian National Aerospace Research Programme (PRORA). The site gives an introduction to the organisation and the scientific and the educational areas covered. It describes CIRA's aerospace activities (which include fluid dynamics, air structures, flight systems and computer science) and testing facilities (which include a plasma wind tunnel, an icing wind tunnel, a transonic research wind tunnel and an aerospace structures impact facility. The projects area of the site describes work being carried out on unmanned aerial vehicles and unmanned space vehicles. The educational area covers topics such as flight safety, pssengers comfort, air transportation and access to space. The general support area provides access to the Library Catalogue. The CIRA Newsletter is also available.

Loades PLC

Loades PLC is predominantly involved in vehicle body design for automobiles. The site offers a guided tour of its facilities and services which include: design engineering, pattern shop, sheet metal fabrication and precision engineering. There is a gallery of photographs of both the plant and completed car body designs. CAD-CAM capabilities are described and there is a client list provided. The site is currently review (January 2006)

MIL-HDBK-5H : Metallic Materials and Elements for Aerospace Vehicle Structures

MIL-HDBK-5H, dated 1 December 1998 is a key military handbook provided by the US Government Department of Defense and Federal Aviation Administration. It is intended primarily as a source of design allowables, which are those strength properties of metallic materials and elements (primarily fasteners) that are widely used in the design of aerospace structures. It contains information and data for other properties and characteristics, such as fracture toughness strength, fatigue strength, creep strength, rupture strength, fatigue-crack propagation rate, and resistance to stress corrosion cracking. It also features some of the more commonly used methods and formulas by which the strengths of various structural elements or components are calculated. This particular online version has been produced by materials information specialists, Granta Designs. The text of the handbook is available as a series of PDF files. Please note that in May 2004 the United States Department of Defense issued a notice of cancellation for MIL-HDBK-5. Future acquisitions may refer to DOT/FAA/AR-MMPDS-01, Metallic Materials Properties Development and Standardization (MMPDS) but users are cautioned to evaluate this document for their particular application before using it as a replacement document.

Milestone Case Histories in Aircraft Structural Integrity

This technical report (NLR-TP-2002-521) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2002 and was written by R. J. H. Wanhill. This report has been prepared as a chapter in an introductory volume of the Elsevier Science treatise "Comprehensive Structural Integrity". The report discusses four milestone case histories in aircraft structural integrity, describing the causes of structural failure and the lessons learned. These case histories are the DeHavilland Comet crashes in 1954, the General Dynamics F-111 crash in 1969, the Dan Air Boeing 707 crash in 1977, and the Aloha Airlines Boeing 737 accident in 1988. [Taken from abstract]. The full text is available as a PDF file.

Modeling, Analysis and Optimization of Cylindrical Stiffened Panels for Reusable Launch Vehicle Structures

This web site provides access to a University of Florida, PhD dissertation, by Satchithanandam Venkataraman, dated 1999. Bibliographic and abstract details are available in HTML format. The title page, contents and the full text of the document are accessible online in PDF format. This title is part of the University of Florida's Electronic Theses and Dissertations Project

NASA Glenn Research Center

Formerly the Lewis Research Center, NASA's lead site for aeropropulsion activities is now officially called the NASA John H. Glenn Research Center at Lewis Field. Specific areas of expertise include: civil and military aircraft propulsion systems, combustion, turbomachinery, materials, structures, internal fluid mechanics, icing, instrumentation, controls and sensors. The Centre has been a major contributor to many past and present NASA missions such as Apollo, Space Shuttle, Mir, Cassini, and the International Space Station. The Center's web site provides access to a wealth of information resources. These include: links to GRC organisations, information on inter-agency as well as Glenn specific projects; news, images and learning resources. Much of Glenn's research and technology work is reported in technical reports, journal articles, and presentations. Bibliographic information, as well as a growing number of full text documents, can be located via the NASA Glenn Research Center Technical Reports Server.

NASA Langley Research Center - Multimedia Repository

This web site provides access to NASA Langley Research Center's library of digital images. The objective of the service is to facilitate online access to digitised photographs, computer-generated images and other digital sources such as movies and videos. All of the images are in JPEG format.Thumbnail (~96x96), Small (~544x480); Medium (~1280x1024) (if available); and Large (~3072x2432) (if available). The repository can be browsed or searched. Browse headings include aircraft, devices, education, events, laboratories, people, projects, space transportation, wind tunnels and new multimedia. The site also contains a Frequently Asked Questions, and a comments/question section.

NASA Tech Briefs Online : Engineering Solutions for Design and Manufacturing

This newsletter site includes articles and news items on the latest spin-off developments from NASA including a TechSearch of over 6000 technologies available for license. Free subscription is available and an archive is available to search as well as a Tech Brief library to browse. A new NanoTech Brief is available as well as news items and articles on the latest developments in the bio-medical, materials, mechanics, motion control, manufacturing, machinery, photonics and test and measurement fields.

National Transportation Strategic Research Plan

This web site provides access to the text of the plan prepared by the US National Science and Technology Council's Subcommittee on Transport Research and Development, dated May 2000. The purpose of the report is to help the establishment of national transport research and technology priorities and to provide a coordinated framework for government, industry and academia. It identifies "breakthrough"research directions including: nanotechnology, biofuels, and complex systems and high-confidence software. The plan looks at areas of enabling research in human performance and behaviour; advanced materials and structures, computing; communications and information technology; energypropulsion and environmental engineering; sensing and measurement; analysis, modeling, design and construction tools; as well as social and economic policy issues. A selection of these are identified as future priority focus areas. The full text of the report is available online in PDF format.

Natural Frequencies and Mode Shapes of a Nonlinear, Uniform Cantilevered Beam

This is the full text of a Master's thesis by Lieutenant Daniel J. Marquez-Chisolm, USAF, AFIT/GAE/ENY/06-S06, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in September 2006. A series of experiments in 1975, referred to as the Princeton Beam Experiments, were performed to measure natural frequencies and create a nonlinear elastic deformation model to improve helicopter main beam designs. These experiments used a homogeneous 7075 aluminum beam and have been referenced as a baseline for the past thirty years to validate computer models and theories in an effort to build beams capable of withstanding aero-elastic, static, and dynamic loading. The purpose of this study is to measure the dynamic nonlinear bending and torsion response of a cantilever beam. The natural frequencies are measured in the flatwise and edgewise directions at different static root pitch angles with varying levels of tip weights. The measured natural frequencies were compared to linear equations of motion, a nonlinear computer model and previous experiments to verify the nonlinear effects of root pitch angle and tip weights. The experiment produced promising results in that the first mode in the edgewise and flatwise directions were within the error bands of the Princeton Beam Experiment and that the linear model matched the experimental case with no tip weights. Further experimentation is needed in order to properly calculate the edgewise frequencies and estimate mode shapes. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

NDT.net : The Online Journal of Nondestructive Testing and Ultrasonics

This electronic journal has been published monthly since 1996. It provides free full text access to online articles and other features relating to non-destructive testing. In addition to the articles, it contains a variety of information resources including: exhibitions and events; web sites; Nondestructive Testing Encyclopedia; electronic discussion forum; and lists of books, journals, and conference proceedings. The archive can be searched or browsed. It contains full text articles and abstracts covering a range of aerospace related topics including: nondestructive inspection; ultrasonic imaging; and aging aircraft structures.

New Analysis and Design Procedures for Ensuring Gas Turbine Blades and Adhesive Bonded Joints Structural Integrity and Durability

This web site provides access to an Ohio State University PhD Thesis, by Hsin-Yi Yen, dated 2000. Bibliographic and abstract details are available in HTML format. The thesis examines the feasibility of using a stress dependent magnetomechanical surface coating material for enhancing high damping capacity on turbine blades. The title page, contents and the full text of the document are accessible online in PDF format (6.24 Mb). This title is part of the OhioLINK Electronic Theses and Dissertations Project.

New Metallic Materials for the Structure of Aging Aircraft

This meb site provides access to a NATO Research and Technology Organization document titled: New Metallic Materials for the Structure of Aging Aircraft, RTO-MP-025, papers from the Applied Vehicle Technology Panel (AVT) Workshop, held in Corfu, Greece, 19-20 April 1999. The workshop featured a series of presentations which address aspects of the the replacement of structural components of aging aircraft with components manufactured from materials of a high qualification. The topics covered include: life cycle costs, aluminium alloys, and the processing, fatigue and durability of composites. Citation and abstract details are in HTML format, and the text is available online in PDF format (15.4 Mbytes).

Nonlinear transient response of thermally loaded laminated panels

This paper was given at the 5th Dynamics and Control of Systems and Structures in Space (DCSSS) conference by D. C. D. Oguamanam, J. S. Hansen and G. R. Heppler. The conference took place in July 2002 at King's College, Cambridge. The nonlinear response of a composite laminated panel suddenly exposed to a heat flux giving rise to a spatially uniform but time-dependent temperature distribution is examined. The panel is cantilevered onto a rigid hub and the elastic deformations are modelled via the von K?arm?an strain-displacement relations and the Reissner-Mindlin kinematic assumptions. The nonlinear governing equations are solved by the Newton-Raphson method in conjunction with the Newmark time integration scheme. The results obtained from the linearized governing equations are presented, along with a parametric study of the effects of the geometric nonlinearity and the panel shallowness. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Office National d'Etudes et de Recherches Aerospatiales (ONERA)

Office National d'Etudes et de Recherches A�rospatiales (ONERA) is the French national aerospace research establishment. It is a scientific and technical public establishment managed according to industrial and commercial practice, placed under the supervision of the Minister of Defense. Its missions are to develop and guide aerospace research; design, develop and implement the facilities it requires to conduct its research and testing; publish and promote the results of its research; and contribute to the education of engineers and scientists. In addition to an overview of current research projects and interests, facilities and expertise, the site does provide a searchable database of scientific publications. This includes articles published in journals, papers delivered before conferences, theses, Technical Notes (NT), other publications, but not unpublished research reports. Some recent documents are available in full text format. An French language version of the site is also available.

ONERA Publications Database

ONERA (Office National d'Etudes et de Recherches Aerospatiale) is the French national aerospace establishment which has expertise in all the disciplines involved in aircraft, spacecraft and missile design. The ONERA database allows for searching of journal articles, papers delivered at conferences, theses, Technical Notes (NT), and other publications. Unpublished ONERA research reports are not included. The full text of selected recent documents is available in PDF format. It is possible to search by author name, information contained within the bibliographic record or the full text (if it is available). Searching in the full text field will return full text reports only.

Open Channel Foundation

The aim of this US based organisation is to publish innovative open source software for a wide range of scientific and engineering applications. Much of the software available from the site has been produced from within the academic and research community. Over 200 software programmes are available. The site offers search and browse access to the software. The list of disciplines covered includes aerodynamics, antenna design and satellite communications; CAD CAM CAE, crack growth and fatigue analysis; digital signal processing, failure analysis, finite element analysis, life support systems, navigation and radar, optics and lasers, spacecraft design, and trajectories and orbital mechanics.

Operational agility

This is Research and Technology Organization (RTO) AGARD-AR-314, dated April 1994. From previous AGARD activities, it was recognized that flying qualities and traditional aircraft performance parameters did not characterize the capability or effectiveness of combat aircraft, although they do offer a guide. Other expert groups had reached a similar conclusion. The subject that arose from these realizations was 'agility'. Recognizing that this was an incomplete or immature concept and that a wide variety of sometimes disparate views existed, the Flight Mechanics Panel formed a further Working Group, WG 19, consisting of specialists from AGARD member countries, to study the subject under the title of 'Operational Agility'. Working sessions were held at places of special interest to the group, between 1991 and 1993. The specific aims of the Working Group were to provide definitions, which are universally acceptable, of the terminologies involved in agility; to collate the results of lessons learned from experiments on agility; to define metrics or figures of merit for use in design and evaluation; to explore and document the theoretical foundations; to explore the operational pay-off of balanced capabilities between the airframe, systems and weapons; to highlight any specialized aspects applicable to rotorcraft; to indicate possible means of evaluation in flight; and to recommend areas for further research and development activities, including possible collaborative projects. The Group has completed its study of operational agility with this report. In undertaking the study, a greater understanding has been reached of those subjects which influence operational agility and how these subjects, via the use of operational agility concepts, may be related to the combat effectiveness of the weapon systems. In reaching this understanding, the Group has proposed definitions of the agility terminology which should prove universally acceptable; it has arrived at the methodology for assessment of the various component systems which contribute to the operational agility or combat effectiveness of a Weapon System; and has listed a number of major conclusions and recommendations. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (28.56MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Operational Evaluation of Health and Usage Monitoring System (HUMS)

This final report (NASA/CR-1998-207409; DOT/FAA/AR-97/64; ARL-CR-420) was published by the Federal Aviation Administration (FAA) in April 1998, and was written by J. Cronkhite et al. This report describes the results of a research program to evaluate structural usage monitoring and damage tolerance methodology using data collected concurrently during a helicopter flight program. In addition to usage monitoring evaluations, guidelines for HUMS certification are discussed along with potential economic benefits and simplified "mini-HUMS" approaches to provide low cost systems with high paybacks [extracted from FAA abstract]. This is a PDF file [57 pages, 1Mb] so Adobe Acrobat software will be required in order to read it.

Outgassing Data for Selecting Spacecraft Materials Online

This site features a database of outgassing data of materials intended for spacecraft use, obtained at the Goddard Space Flight Center (GSFC) Materials Engineering Branch, and utilising equipment developed at Stanford Research Institue (SRI) under contract to the Jet Propulsion Laboratory (JPL). The site provides a system description, and the possibility to download the entire Outgassing database. The Outgassing Materials Search function provides the capabilility to search all across materials tested at GSFC for determining the mass loss in a vacuum and for collecting the outgassed products. A Manufacturer Lookup allows to search on manufacturer name or code, or to browse the manufacturer list. There are also category and alphabetical listings and a report documentation page.

POD Assessment of NDI Procedures Using a Round Robin Test

This is Research and Technology Organization (RTO) AGARD report, AGARD-R-809, dated January 1995. Under the auspices of the AGARD Structures and Materials Panel R&D Cooperation Program, a round-robin NDI demonstration has been carried out. Six laboratories in four NATO countries participated in the project. The aim of the project was to determine the sensitivity and reliability of NDI procedures presently employed by the participating laboratories and to establish whether or not the procedures would be adequate for the implementation of a damage-tolerance based maintenance approach or whether improved methods are required. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (5.96 MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

PrePRINT Network : Department of Energy

This service is a searchable gateway to preprint servers provided by the US Department of Energy (DOE) Office of Scientific and Technical Information (OSTI). It is possible to search one site, a group of sites, or all the sites, or to browse an alphabetical listing of all preprint sites included on the service. An additional feature notifies individuals of new preprints that match a personally defined profile of subject interests. Subject areas covered include physics, mathematics, computer science, nonlinear sciences, engineering, and materials science.

Principles of biodynamics applicable to manned aerospace flight prolonged linear and radial acceleration

This is Research and Technology Organization (RTO) AGARD-AG-150 , dated March 1971. The Biodynamics Committee of the Aerospace Medical Panel of AGARD-NATO observed in 1961 that, because of the burgeoning of scientific talent into the aerospace biomedical fields, there was a need to inform the new scientists of the basic principles which had been accumulated over many years of earlier aeromedical research. In an attempt to clarify the area of its own specialty, the Biodynamics Committee of the Aerospace Medical Panel, AGARD-NATO, received permission from the Aerospace Medical Panel to compile a "Comparative Table of Acceleration Terminologies. The Biodynamics Committee concluded that it could assist further by compiling a series of monographs covering the generally accepted basic information in the fields of prolonged radial and linear acceleration, including the physics, physiology, and tolerance limits. The current volume has been expanded over the previous addition, principally by the inclusion of an annotated bibliography, which covers, in addition to publications in the area of acceleration, selected references in the areas of impact, vibration and combined stresses. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (47.63MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Proceedings of SPIE

SPIE is a non-profit professional society dedicated to advancing research, engineering, and applications in optics, photonics, imaging, and electronics. Proceedings of SPIE contains papers on new research and applications in optical, photonic, imaging, and optoelectronic technologies. This web page features recent proceedings and provides browse access to recent proceedings by title. Aerosence (sensors), microelectronic manufacturing, and smart structures, are among the annual meetings, for which individual paper abstracts are available. A link is provided to the SPIE Digital Library which currently includes descriptions of more than 120,000 technical papers from SPIE Journals and Conference Proceedings.

Proceedings of the FAA-NASA Symposium on the Continued Airworthiness of Aircraft Structures : Vol. 1

Compiled by Catherine A. Bigelow, these proceedings (DOT/FAA/AR-97/2) were published in July 1997 by the Federal Aviation Administration (FAA). This collection of papers on airworthiness of aircraft structures discusses airframe life extension through quantitative rework inspections, analysis of a composite repair, analytical fatigue life estimation of full-scale fuselage panels, and application of acoustic emissions (AE) to health monitoring of helicopter mechanical systems. This is a PDF file so Adobe Acrobat software will be required in order to read it.

Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering

Published six times a year, the Journal of Aerospace Engineering is a forum for the communication of ideas and methods presently in use at the forefront of technology in the field of aerospace engineering. It contains papers on both theoretical and practical aspects of all types of civil and military aircraft and spacecraft and their support systems. The scope is wide, covering research, design, development, production, operation, servicing and repair, components and auxiliary equipment, safety and reliability. The site provides contents information for the journal. If you wish to view full text check with your library to see if they have a subscription.

Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications

Published four times a year, the Journal of Materials: Design and Application, is a forum for the communication of ideas and methods presently in use at the forefront of technology in the field of materials science. This journal is addressing a whole range of materials engineering and technology, which includes metallic materials, polymers, composites and ceramics. In addition, metal matrix composites and ceramic matrix composites are part of the portfolio. The site provides contents information for the journal. If you wish to view full text check with your library to see if they have a subscription.

QinetiQ

Established in July 2001, QinetiQ comprises the greater part of what was the Defence and Evaluation Research Agency (DERA). QinetiQ has a wide range of science and technology interests including aerospace, defence, electronics, finance, healthcare, offshore, marine and offshore, telecommunications and media, security, space and transport. The web site describes the technogy areas in which QinetiQ have particular expertise as well as the industry and service sectors in which the company specialises. There is a selection of case studies which can be browsed by industry sector or searched by keyword. There is an 'About' section which contains financial information, details of where the business elements are located and an overview of the historical development of the company. The site also includes press releases, feature articles, careers information and a short introductory video (Running Time: 02:30) about the organisation.

Real Time Failure Detection in Smart Structures using Wavelet Analysis

This paper was given at the 5th Dynamics and Control of Systems and Structures (DCSSS) conference by M-F. Dandine and D. Necsulescu. The conference took place in July 2002 at King's College, Cambridge. Flexible structures equipped with piezoelectric actuators and sensors have the capability of detecting in real time the occurrence of defects in structural connections by generating flexural excitations and analysing the response. In previous work, this method used transient response and frequency analysis for computing damage index for the flexible structure. In the present paper a new approach, based on wavelet analysis is proposed. Analytical and experimental results illustrate the capability of the proposed method to detect the occurrence of failures in smart structures. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Real-Time Simulation of Impact for the Aerospace Industry

This technical report (NLR-TP-1999-289) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 1999 and was written by A.A. ten Dam and J. Kos. In this paper a number of issues on impact in mechanical systems are presented. Emphasis is on modelling, simulation and control in a real-time setting for aerospace applications. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Repair Assessment Procedure and Integrated Design (RAPID) Version 2.1 : Analysis Methods Document

Produced in May 1998, this document describes technical details of the analysis methodology used in the static and damage tolerance analysis modules of the Repair Assessment Procedure and Integrated Design (RAPID) Version 2.1 program. In this document, the static strength analysis method for repaired fuselage skin is first described. Next, a description of the damage tolerance analysis method is provided which includes the prediction of crack growth and residual strength and the calculation of inspection threshold and interval. This document also includes descriptions of the methods developed for the damage tolerance analysis of common repairs including a repair near another repair, repairs at stiffeners, and repairs over splice joints. Flow charts of static and damage tolerance analysis methods are provided [taken from the document introduction]. This is a PDF file [200 pages, 1.93Mb] so Adobe Acrobat software will be required in order to read it.

Repair Assessment Procedure and Integrated Design (RAPID) Version 2.1 : User's Manual

Dated June 1998, this document provides installation and usage instructions for the Repair Assessment Procedure and Integrated Design (RAPID) program. RAPID is a tool for the design and analysis of aircraft structural repairs. This version assists the user in designing mechanically fastened fuselage skin repairs with up to three doublers. RAPID performs both static and damage tolerance analyses of the repair. The static analysis determines if the doublers and fasteners are statically adequate, while the damage tolerance analysis yields inspection intervals and residual strength [extracted from FAA abstract]. This is a PDF file [151 pages, 1.38Mb] so Adobe Acrobat software will be required in order to read it.

Review of Aeronautical Fatigue Investigation in the Netherlands During the Period March 1999 - March 2001

This technical paper (NLR-TP-2001-245) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2001 and was written by H. H. Ottens. The present review gives a brief summary of the work performed in the Netherlands in the field of aeronautical fatigue, during the period from March 1999 until March 2001. The various contributions to this review come from the following sources: The National Aerospace Laboratory NLR, The faculty of Aerospace Engineering, Delft University of Technology (TU Delft), Stork Aerospace Fokker Services and Stork Aerospace Fokker Aerostructures. The names of the principal investigators and their affiliation are presented between brackets at the end of each topic title. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software is required in order to read it.

Review of Aeronautical Fatigue Investigations in the Netherlands During the Period March 2001 - March 2003

This technical report (NLR-TP-2003-251) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2003 and was written by H.H. Ottens and R.J.H. Wanhill. A review is presented of the aeronautical fatigue research carried out in the Netherlands in the period March 2001 to March 2003. [Taken from abstract]. The full text is available as a PDF file.

Review of Damage Tolerance for Composite Sandwich Airframe Structures : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-99/49, by J. Tomblin and others, dated August 1999. The report presents a review of previous damage tolerance investigations. It includes a compilation of damage tolerance certification procedures; a survey of past and current airframe industry sandwich constructions; and recommendations for future research. The full text of the report is available in PDF format from the online catalogue of the FAA William J. Hughes Technical Center Library.

School of Aeronautical Engineering at Queen's University, Belfast

The School of Aeronautical Engineering has research interests in the following areas: aerodynamics, aircraft structures and integrated aircraft technology. The Web site provides information about past and current projects that are being undertaken in these fields and selected papers produced by staff. It also contains details of the courses on offer by the department as well as a full staff list with biographies.

Shear Stress-Strain Data for Structural Adhesives : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/97, by John Tomblin, Waruna Seneviratne, Paulo Escobar, and Yap Yoon-Khian, dated November 2002. The main objective of this investigation was to generate characteristic shear responses for several adhesives used for aerospace structural bonding applications. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library.

Side Load Factor Statistics From Commercial Aircraft Ground Operations : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-02/129, by Daniel O. Tipps, John Rustenburg and Donald Skinn, dated January 2003. The primary objective of this research is to support the FAA�s Operational Loads Monitoring Research by developing new and improved methods and criteria for processing and presenting commercial transport airplane flight and ground loads usage data.The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center library

Simulation of a Moving Elastic Beam Using Hamilton's Weak Principle

This is the full text of a Master's thesis by First Lieutenant Elliott J. Leigh, USAF, AFIT/GAE/ENY/06-M21, which was presented to the Faculty Department of Aeronautical and Astronautical Engineering of Air University's Air Force Institute of Technology (AFIT), in March 2006. Hamilton's Law is derived in weak form for slender beams with closed cross sections. The result is discretized with mixed space-time finite elements to yield a system of nonlinear, algebraic equations. An algorithm is proposed for solving these equations using unconstrained optimization techniques, obtaining steady-state and time accurate solutions for problems of structural dynamics. This technique provides accurate solutions for nonlinear static and steady-state problems including the cantilevered elastica and flatwise rotation of beams. Modal analysis of beams and rods is investigated to accurately determine fundamental frequencies of vibration, and the simulation of simple maneuvers is demonstrated. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

Smart Structures and Materials: Implications for Military Aircraft of New Generation

This is Research and Technology Organization(RTO) AGARD Lecture Series, AGARD-LS-205, dated October 1996. It is sponsored by the Advisory Group for Aerospace Research and Development of AGARD. Smart materials and structures technology is the integration of sensing and actuation elements into a structure or even more ambitiously into a material, with sensor and actuator being linked by a controller. Materials actually favored for integration include optical fibers and piezoelectric materials with respect to sensors, piezoelectric and electrostrictive materials, shape memory alloys or electro-rheological fluids with respect to actuators and microprocessors, neural networks, fuzzy logic and various types of signal processing with respect to control. The first part of the lecture series is mainly focussed on understanding the fundamentals of smart materials and structures technology and achieving the capability to judge the use of that technology with respect to individual applications. Presentations related to sensor and actuator materials, mechanics of smart structures, control and data processing, as well as structural integration of sensors, actuators, and generally electronics are therefore the focus of this part. In a second part, applications of smart structures technology are considered with respect to aircraft. Topics to be covered include monitoring the health/damage of aircraft structures or components, conceptual design of an adaptive wing, and electromagnetic antennae and their structural integration. For individual titles, see N97-11476 through N97-11487. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Smart Structures for Aircraft and Spacecraft

This is Research and Technology Organization (RTO) AGARD-CP-531, dated April 1993. An overview of the state-of-the-art of 'Smart Structures' technology as well as detailed descriptions of specific applications is presented. This technology offers extremely attractive advantages in the design, development, and operation of aerospace structures. For individual titles, see N94-11318 through N94-11347. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (117.93MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Smart Structures for Control of Optical Surfaces

This is the full text of a thesis by Michael D. Sobers which was presented to the Air Force Institute of Technology (AFIT) in 2002. The development of lightweight, large-aperture optics is of vital importance to the Department of Defense and the US Air Force for advancing remote sensing applications and improving current capabilities. Synthetic polymer optics offer weight and flexibility advantages over current generation glass mirrors, but require active control to maintain tight surface figure tolerances. This research explores the feasibility of using imbedded piezoelectric materials to control optical surfaces. Membrane-based and stiff piezo-controlled mirrors were constructed to develop and validate control techniques. Test results verified that surface control on the order of tens of wavelengths is possible using these systems. [Taken from abstract]. The full text of the thesis is available in PDF format and is provided by the Air University ResearchWeb site.

Some Aspects of the Mechanical Response of PMR-15 Neat Resin at 288 deg. C: Experiment and Modeling

This is the full text of a Master's thesis by 2nd Lieutenant Christina M. Falcone, USAF, AFIT/GAE/ENY/06-S03, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in September 2006. The mechanical response of PMR-15 neat resin was investigated at 288?C. Monotonic loading/unloading tests performed at several constant stress rates revealed considerable rate dependence, especially on the unloading path. Effect of prior stress rate on creep behavior was evaluated in creep tests preceded by uninterrupted loading to a target stress. Creep response was dependent on the prior stress rate. Effect of loading history was studied in stepwise creep tests, where specimens were subjected to a constant stress rate loading followed by unloading to zero stress with intermittent creep periods during both loading and unloading. Comparison of creep strains accumulated during a stepwise creep test to those accumulated during creep preceded by uninterrupted loading indicate that the prior stress history affects the creep behavior. A nonlinear viscoelastic model (Schapery?s formulation) was characterized using creep and recovery tests. The model was verified by comparing the predictions with experimental results obtained in monotonic loading/unloading, single-step, and multi-step creep tests. The model qualitatively predicted creep response to single- and multi-step creep tests, including negative creep and creep rate reversal during unloading. However, predictions were not quantitatively accurate. The model was unable to accurately predict the recovery behavior and could not account for rate effects. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

Special Course on Unstructured Grid Methods for Advection Dominated Flows

This is Research and Technology Organization (RTO) AGARD-R-787 , dated May 1992. Lecture notes for the AGARD Fluid Dynamics Panel (FDP) Special Course on 'Unstructured Grid Methods for Advection Dominated Flow' have been assembled in this report. The objective of this course was to provide state of the art information, as well as recent developments in unstructured grid methods, suitable for the computation of high Reynolds number compressible and incompressible flows, and other related subjects. A wide range of applications is presented, which includes incompressible free surface problems, transonic aerodynamics, and hypersonic reentry flows. For individual titles, see N92-27672 through N92-27680. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (56.05MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

SPIE - The International Society for Optical Engineering

SPIE is a non-profit professional society dedicated to advancing research, engineering, and applications in optics, photonics, imaging, and electronics. The site provides access to a range of information resources. These include: details of SPIE education programmes, information on SPIE's technical meetings and symposia, details of employment opportunities and candidates for vacancies in the optics, photonics and imaging industries. There are a series of SPIE technical listserver groups. Publication information is heavily featured on the site, and includes a database of proceedings and papers. Selected articles from SPIE's monthly news publication, OE Reports, are available online. The Photonics Gateway provides access to the WWW Virtual Library for Optical Science and Engineering.

SPIE Web Bookstore

SPIE is a non-profit professional society dedicated to advancing research, engineering, and applications in optics, photonics, imaging, and electronics. The SPIE Web bookstore offers search and browse access to bibliographic citations and abstracts from SPIE proceedings and SPIE scholarly journals, including: Optical Engineering; Journal of Electronic Imaging, and Journal of Biomedical Optics. The search facility provides simple and fielded search options. It is possible to browse by technology, and headings for this include: aerospace, remote sensing and astronomy, automation, inspection and product engineering, communication and fibre optics, and lasers and applications.

Statistical Data for the Boeing 747-400 Aircraft in Commercial Operations

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA/AR-04/44 by Todd Jones ...[et al] dated January 2005. The Federal Aviation Administration (FAA), supported by the University of Dayton, conducts research on the structural integrity requirements for the U.S. commercial transport airplane fleet. The primary objective of this research is to support the FAA airborne data monitoring systems research program by developing new and improved methods and criteria for processing and presenting large commercial transport airplane flight and ground loads usage data. The scope of activities performed involved (1) defining the service-related factors that affect the operational life of commercial aircraft; (2) designing an efficient software system to reduce, store, and process large quantities of optical quick-access recorder data; and (3) providing processed data in formats that will enable the FAA to reassess existing certification criteria. Equally important, these new data will also enable the FAA, the aircraft manufacturers, and the airlines to better understand and control those factors that influence the structural integrity of commercial transport aircraft. Presented herein are analyses and statistical summaries of the data collected from 11,066 flights representing 95,883 flight hours from Boeing 747-400 aircraft during operational usage recorded by a single airline. The flight loads data include statistical information on accelerations, speeds, altitudes, flight duration and distance, gross weights, speed brake cycles, thrust reverser usage, and gust velocities encountered. In addition, specialized aircraft usage data that the FAA can use to support development of ground loads certification criteria are included. These new data formats show aircraft usage as it relates to aircraft speed, attitude, and rate data at touchdown by airport. Statistical data were also developed to provide the FAA with information that it can use to establish the initial design requirements for an onboard nitrogen-generating system to be used for fuel tank inerting. These statistical formats were developed from 1984 flights to show how the B-747-400 descent rates vary during the descent phase of the flight as a function of altitude, gross weight, engine rotor speed, and computed airspeed for operations into capacity-limited and non-capacity-limited airports. [Taken from abstract]. The fukll text of the report is available in PDF format from the online catalogue of the FAA William J Hughes Technical Center Library.

Statistical Loads Data for Boeing 737-400 Aircraft in Commercial Operations

A final report (DOT/FAA/AR-98/28) produced by the Federal Aviation Administration (FAA) in August 1998 and written by John Rustenburg et al. The University of Dayton is supporting Federal Aviation Administration (FAA) research on the structural integrity requirements for the US commercial transport airplane fleet. The primary objective of this research is to support the FAA Airborne Data Monitoring Systems Research Program by developing new and improved methods and criteria for processing and presenting large commercial transport airplane flight and ground loads usage data. The statistical data presented include the initial recorded data previously reported in FAA report DOT/FAA/AR-95/21. The data include statistical information on accelerations, speeds, altitudes, flight duration and distance, gross weights, speed brake/spoiler cycles, thrust reverser usage, and gust velocities encountered [extracted from FAA abstract]. This is a PDF file [86 pages, 562Kb] so Adobe Acrobat software will be required in order to read it.

Statistical Loads Data for Cessna 172 Aircraft using the Aircraft Cumulative Fatigue System (ACFS) : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-01/44, by John A. Cicero, Frank L. Feiter and Jamshid Mohammadi, dated August 2001. The report describes the development and testing of a low-cost Airframe Cumulative Fatigue System (ACFS). It includes the analysis and statistical summaries of the data collected from 1000 test flights on a Cessna 172. The full text of the report is available in PDF format.

Statistical Testing of Aircraft Materials for Transport Airplane Rotor Burst Fragment Shielding

This technical report (DOT/FAA/AR-06/9) was published by the Federal Aviation Administration (FAA) Office of Aviation Research in June 2006 and was written by Sean Kelley and George Johnson. Fragment barrier systems are being examined and developed for commercial airplanes to prevent accidents as a result of an engine rotor burst failure. To use this system, it is necessary to understand how the existing aircraft materials behave under ballistic impact. The material response of 0.063, 0.125, and 0.25-in-thick 2024 aluminum, 0.25-in-thick Makrolon® polycarbonate, and sandwich composite panels were investigated under ballistic impact. Failure modes were evaluated and ballistic limits obtained for each set of targets. The testing was done in the UC Berkeley Ballistics Laboratory using a gas gun, and a powder gun setup with a 1/2-inch diameter chrome steel spherical projectile. This report documents the testing and analysis of the UC Berkeley ballistic testing. The testing yielded excellent results on aluminum but more data is needed for titanium, composites, and polycarbonate materials. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it.

Strain gauge measurements on aircraft, volume 7

This is Research and Technology Organization (RTO) AGARD-AG-160-VOL-7, dated April 1976. Various subjects related to the application of strain gauges to aircraft structures were presented. These include: (1) introductory discussion, (2) physical properties of strain gauges, (3) measurement of resistance changes in strain guages, (4) error estimation for strain gauges with metallic measuring grids, (5) types of strain guages, (6) applications of strain gauges for static and dynamic short and long term measurements under normal conditions, (7) strain gauges for special applications, (8) use of strain gauges under extreme environmental conditions, (9) instrumentation of two VAK 191 B aircraft with flight load measuring systems. For individual titles, see N76-25581 through N76-25589. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (7.41MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Stress-Intensity Factors along Three-Dimensional Elliptical Crack Fronts

A final report (DOT/FAA/AR-96/97) produced by the Federal Aviation Administration (FAA) in May 1998 and written by M. Gosz and B. Moran. The objective of the investigation is to determine the mode I stress-intensity factors along two symmetric surface cracks emanating from a centrally located hole in a rectangular plate (the so-called Round Robin Problem) using the domain integral method [extracted from FAA abstract]. This is a PDF file [14 pages, 167K] so Adobe Acrobat software will be required in order to read it.

Stress-Intensity Factors for Elliptical Cracks Emanating from Countersunk Rivet Holes

A final report (DOT/FAA/AR-95/111) produced by the Federal Aviation Administration (FAA) in April 1998 and written by M. Gosz and B. Moran. Small cracks developing from rivet holes in lap joints of fuselage structure have been an issue of concern over the past decade. Stress-intensity factor solutions required to assess the structural integrity of such configurations are lacking. To address this need, the domain integral method was used in this research to obtain the mode I, normalized stress-intensity factor distributions for cracks emanating from a centrally located countersunk rivet hole in a square plate subjected to remote tension. Particular attention was focused on short cracks with an elliptical shape that have not propagated through the thickness [extracted from FAA abstract]. This is a PDF file so Adobe Acrobat software will be required in order to read it.

Structural Aspects of Flexible Aircraft Control

This web site provides access to a NATO Research and Technology Organization (RTO) document titled: Structural Aspects of Flexible Aircraft Control, proceedings of the Specialists Meeting of the RTO Applied Vehicle Technology Panel (AVT), held in Ottawa, Canada, 18-20 October 1999, RTO-MP-036, May 2000. The report contains 26 papers and a keynote address that address design issues and more specifically structural aspects of flexible aircraft control. There were three sessions covering the following topics: Aeroservoelasticity; Active Control of Flexible Structure I; and Active Control of Flexible Structure II. Citation and abstract details are in HTML format, and the full text is available online in PDF format (35.8 Mbytes).

Structural design applications of mathematical programming techniques

This is Research and Technology Organization (RTO) AGARD-AG-149, dated February 1971. The Structures and Materials Panel of the Advisory Group for Aerospace Research and Development (AGARD) comprises scientists , engineers and technical administrators from government, universities and industry, who are concerned with the advancement of aerospace research and development and with the provision of data necessary for the design and fabrication of the vehicles and equipment which NATO requires. The panel provides a mechanism for discussion, the exchange of information and for conducting co-operative theoretical and experimental studies in selected areas. This volume describes the present state of development of the use of mathematical programming techniques in the optimum design of aerospace and similar structures. Although optimization with respect to cost is considered when possible, the main emphasis is on the minimization of weight, due to the overwhelming importance of this parameter in aerospace applications, and also due to the fact that it is one of the few merit functions that can be defined with reasonable precision. The use of mathematical modelling techniques in the selection of materials is also discussed to the limited extent meaningful at the present time. This report is divided into four main sections. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (16.19MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Structural Health Monitoring and Detection of Progressive and Existing Damage using Artificial Neural Networks-Based System Identification

This is a North Carolina State University (NCSU), Department of Electrical Engineering PhD dissertation, by Soheil Saadat, dated 25th February, 2003. This dissertation presents a novel "Intelligent Parameter Varying" (IPV) health monitoring and damage detection technique that accurately detects the existence, location, and time of damage occurrence without any assumptions about the constitutive nature of structural non-linearities. This technique combines the advantages of parametric techniques with the non-parametric capabilities of artificial neural networks by incorporating artificial neural networks into a traditional parametric model. This IPV technique is demonstrated using a lumped-mass structural model with an embedded array of artificial neural networks. Bibliographic and abstract details are available in HTML format. The full text of the document is accessible online in PDF format [52.84 Mb]. This title is part of North Carolina State University's Electronic Thesis and Dissertation (ETD) Collection

Structural Health Monitoring Considering Internal Beam Damage

This is the full text of a Master's thesis by Second Lieutenant Jessica B. Chronister, USAF, AFIT/GA/ENY/06-M09, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2006. The present study establishes a nondestructive method of damage detection and assessment in cantilever beams. The specimens used are twelve-inch aluminum 2024-T3 beams with machined notches of varying lengths and locations. Laser Doppler vibrometry is used to obtain the frequency response of vibrating beams. Experimental methods are developed to detect the presence, location and extent of damage by direct observation of the eigenvector in the third through eighth modes. Models in MATLAB and ABAQUS are used to predict and validate the observed data. With this experimental method developed, the validity of the method is tested for specimens that have been exposed to a destructive corrosive environment. A corrosion experiment is developed and used to determine the validity of the damage detection method for corroded structures. [Taken from abstract]. The full text is available in PDF format on the Scientific and Technical Information Network (STINET) which is provided by the Defense Technical Information Center (DTIC).

Survey of Aircraft Structural-Life Management Programs in the U.S. Navy, the Canadian Forces, and the U.S. Air Force

This technical report (MG-370-AF) was published by the RAND Corporation in 2006 and was written by Yool Kim, Stephen Sheehy and Darryl Lenhardt. The U.S. Air Force owns and operates some 6,000 aircraft, with an average age of 22 years. Many of the older aircraft are facing aging issues. Since 1958, the Air Force has relied on its Aircraft Structural Integrity Program to maintain the safety of its aircraft throughout their service lives. In recent years, concerns have arisen about the aging force, budget pressures, diminishing program regulation, and communication challenges. The authors have addressed these concerns by comparing the Air Force program with its peers in the U.S. Navy and Canadian Forces, seeking insights that might help the Air Force enhance its own program’s effectiveness. Some of these insights include the value of clarifying the program’s policies and extending and formalizing existing processes, providing independent compliance assessment, facilitating communications and close working relationships, and standardizing metrics and communications to improve the command’s understanding of the conditions of all its aircraft. [Taken from abstract]. The full text is in PDF format so Adobe Acrobat software will be required in order to read it.

Swedish Defence Research Agency

The Agency (Totalf?arets forskningsinstitut - FOI) was formed on 1 January 2001 through an amalgamation of the Swedish Defence Research Establishment (FOA) and the Aeronautical Research Institute (FFA). The site provides an overview of the organisational structure, including the Division of Aeronautics, FFA, which is made up of the core of the former Aeronautical Research Institute. There is a searchable and browsable database of FOI reports. For browsing purposes the reports are sorted by department. The text of the reports are avialable in PDF format.

Technical evaluation report on AGARD Specialists' Meeting on Aerodynamic Interference

This is Research and Technology Organization (RTO) AGARD-AR-34, dated May 1971. The AGARD Fluid Dynamics Panel organised a three-day Specialists' Meeting on "Aerodynamic Interference" that was held at the U.S. Naval Ordnance Laboratory. This meeting was intended to provide a forum for the discussion of theories and experiments to explain the existing comprehension of aerodynamic interference; and to provide some guidelines and design rules to improve the flight characteristics of military and commercial aircraft and weapons. The speed regimes were restricted to subsonic, transonic and supersonic mach numbers. The objectives of this report is to assess current state-of-the art of the analytical and test techniques concerned with junction flows (in terms of that which was preached and that which should have been recited, perhaps), to outline their advantages and disadvantages and to Indicate any relevant omissions. In particular, it should strive to show the practical applications of the work presented with the view of immediate help to the aircraft designer. It was considered that the report should be candid and forthright to stimulate discussion, accepting, of course, that an element of the author's personal bias would be involved. The report is split essentially into three parts: following a synopsis, an attempt is made to give a constructive review of the papers presented, subsequent to which some clear-cut conclusions are drawn. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (6.13MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

The characterization and application of materials

This is Research and Technology Organization (RTO) AGARD-LS-51, dated May 1971. This is a lecture series edited by the Structures and Materials Panel and the Consultant and Exchange Programme of AGARD. The Lecture Series will begin with a discussion of the systems approach to the selection and application of materials, to be given by Dr Robert Maddin. The second in the series will be given by Dr Walter S.Owen and will be primarily concerned with the characterization, selection and use of high strength steels. The third lecture will be given by Dr Joseph Pask and will be concerned with the characterization, selection and uses of ceramic materials. The fourth in the series will be given by Professor Wippler and will cover the characterization, selection and use of polymeric materials. Dr Kelly will present the fifth lecture which will deal with characterization, selection and use of composite materials. The last lecture will cover two fields of special interest to aerospace: aluminium alloys and titanium, their characterization and selection aspects. This lecture will be divided into two parts and will be presented by Mr Syre for the titanium, and by Mr Tigeot for the aluminium alloys part of the paper. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (25.52 MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

The Composite Materials Handbook

The site is maintained by the MIL-17 organisation in order to disseminate and share information on composite materials. The site is primarily concerned with supporting the use of MIL-HDBK-17. This handbook is jointly produced by the Department of Defence and the Federal Aviation Administration. It documents engineering methodologies for the development of standardised, statistically-based material property data for polymer matrix composites. It also provides selected guidance on materials selection, materials specification, material processing, design, analysis, quality control, and repair of typical polymer matrix composite materials. The site describes the content of the volumes, a user's forum, links to related documents, and instructions on how to obtain copies of the handbook. Please note that the text of MIL-HDBK-17/1-5 are available online from the Assist-Quick Search web site.

The Development of a Finite Element Program to Model High Cycle Fatigue in Isotropic Plates

The site provides access to an Air University, Air Force Institute of Technology, Graduate School of Engineering and Management, MSc Thesis, by 1st Lieutenant William C. Shipman, AFIT/GA/ENY/01M-08, dated March 2001. The thesis describes the development of a computer programme that uses a von Karman large-deflection two-dimensional finite element approximation to determine stress levels and patterns in isotropic thin plates. Citation details and an abstract are available in HTML format. The full text can be accessed in PDF format. The document is part of the Air University Research Database

The Use of In-Service Inspection Data in the Performance Measurement of Non-Destructive Inspections

This report (RTO-TR-AVT-051) was published by the Research and Technology Organisation (RTO) in March 2005 by Alan Berens et al. Most available non-destructive inspection (NDI) reliability data results from analyses under laboratory or simulated in-service conditions. Adding analyses of in-service NDI findings could improve NDI. There is no organized process whereby in service data are collated for NDI reliability studies. The extent of this data and its usefulness to the NDI reliability program was analysed and processes for collection were defined as well as analytical methods to calculate NDI reliability from in-service data. Findings: One major contribution is a detailed summary of the close relationship between NDI, fracture mechanics and airworthiness including an important review of the statistical basis for many of current approaches to inspection. NDI maintenance records were reviewed for their usability to pooling of data from different sources in order to obtain statistically significant numbers. It was concluded that such records vary considerably in quality and fidelity and specific recommendations for improvement were made. Of the three approaches for using in-service inspection data to characterize the capability of an inspection system two aiming at characterizing NDI capability in terms of the probability of detection were rejected (POD) because in maintenance too many cracks of a detectable size are not detected rendering the basis data unreliable. A third approach summing inspection results in terms of the cumulative distribution function (CDF) of the sizes of the detected cracks does provide information about the capability of the NDI system in the in-service environment. The CDF does not directly yield the reliably detectable crack size (at a given confidence level) but it gives a first estimate of this size. [Taken from abstract]. The full document is available as an FTP file, or each chapter may be viewed individually.

Thermophysical properties of solid materials - Cooperative thermal expansion measurements up to 1000 C. Project section 1A

This is Research and Technology Organization (RTO) AGARD-AR-31, dated March 1971. As a part of a major project concerning thermophysical properties of solid materials at high temperatures this is a report on the special section of this project dealing with thermal expansion up to temperatures of 1000°C. The complete project TX 44 is aimed at determining absolute accuracy of thermophysical property data of engineering materials at high temperatures by means of a cooperative measurement programme. The results are to indicate the best way of obtaining accurate data. This involves clarifying the following: (1) whether it is best to experimentally determine the properties of a material at the temperatures for which the data are needed, (2) whether known low temperature values on the material considered should be extrapolated to high temperatures, (3) whether it is better to derive estimated high temperature data of the material considered by a comparison with a similar material whose data are available from data compilations. Additionally the aim of the Project Section "Thermal Expansion up to 1OOO"C" is to determine the thermal expansion of solid materials up to 1000°C, which is considered conventionally as the most simple measurement within the realm of thermophysical property measurements. Customarily such measurements, especially in industrial laboratories, are performed by means of pushrod dilatometers, using both quartz glass and alumina reference systems. In as much as this type of apparatus does not yield absolute values and the accuracy of data obtained thereby is frequently considered in doubt, it is a special objective of this project section to determine the accuracy of this type of measurements by using the noble metals gold and platinum. A further objective is to investigate the thermal expansion behaviour of technical materials up to 1OOO"C, to find out if such materials can be used as calibration standards and to establish if an extension of the study on these materials to higher temperatures is justified. Bibliographic and abstract details are available in HTML format. A table of contents and the full text (6.02MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Three-Dimensional Dynamic Stress Analysis of Sandwich Panels

The site provides access to an Air University, Air Force Institute of Technology, Graduate School of Engineering and Management, PhD Dissertation, by Victor Y. Perel, AFIT/DS/ENY/00-02, dated June 2000. This describes the development of a layerwise geometrically nonlinear theory for a thick sandwich plate by introducing assumptions on a variation of transverse strains in the thickness direction of the faces and the core of the plate. Citation details and an abstract are available in HTML format. The full text can be accessed in PDF format. The document is part of the Air University Research Database.

Tutorial Page of Aerospace Structures (TuPAS)

The Tutorial Page of Aerospace Structures (TuPAS) was developed by Masoud Rais-Rohani of the Department of Aerospace Engineering at Mississippi State University to support the teaching of structural analysis at the University. The tutorial provides information on the major topics of aircraft structural design analysis and was last updated in 2006. The chapters are as follows: Pure Torsion, Pure Bending, Transverse Shear Loading of Beams With Open and Closed Cross Sections, Combined Transverse Shear, Bending, and Torsion Loading and Internal Pressure. Please note in order to enter the tutorial you have to enter an e-mail address.

Two-Level Optimization of Composite Wing Structures Based on Panel Genetic Optimization

This web site provides access to a University of Florida, PhD dissertation, by Boyang Liu, dated 2001. Bibliographic and abstract details are available in HTML format. The title page, contents and the full text of the document are accessible online in PDF format. This title is part of the University of Florida's Electronic Theses and Dissertations Project.

Uncontained Engine Debris Analysis Using the Uncontained Engine Debris Damage Assessment Model

This provides access to a Federal Aviation Administration (FAA) report DOT/FAA AR-04/16 by Silvia Seng, John Manion, and Chuck Frankenberger dated September 2004. As part of the Federal Aviation Administration�s (FAA) Aircraft Catastrophic Failure Prevention Program, the Naval Air Warfare Center was tasked to examine and evaluate the Uncontained Engine Debris Damage Assessment Model (UEDDAM). UEDDAM was written to provide a standardized tool for uncontained engine rotor failure analysis. This study was conducted to exercise the code and evaluate its usefulness in performing rotor burst analysis on a small generic business jet and a generic twin-engine aircraft. This evaluation also supported the Aviation Rulemaking Advisory Committee, Power Plant Installation Harmonization Working Group activities. This report explains the analysis methodology, results, and trade studies performed using UEDDAM. Though the aircraft used in the study do not represent a specific aircraft, industry input was used to create the input data required so that the results would be comparable to a real aircraft analysis. [Taken from abstract]. The full text of the report is available in PDF format from the online catalogue of the FAA William J. Hughes Technical Center Library.

Uniaxial and Biaxial Tests on Riveted Fuselage Lap Joint Specimens

This final report (DOT/FAA/AR-98/33) was published by the Federal Aviation Administration (FAA) in October 1998, and was written by H. Vlieger and H.H. Ottens. As a part of a collaboration program between the Federal Aviation Administration (FAA, USA) and the Department of Civil Aviation (RLD, the Netherlands), the Dutch National Aerospace Laboratory (NLR) has carried out fatigue tests on riveted lap joint specimens. The specimens are representative of the longitudinal lap joints of a commercial aircraft in which multiple-site damage (MSD) was found in service. Two different rivet configurations, dimpled and countersunk riveted joints, were investigated [Extracted from FAA abstract]. This is a PDF file [56 pages, 2.07Mb] so Adobe Acrobat software will be required in order to read it.

United States Navy and Marine Corps School of Aviation Safety

The site of the US Navy and Marine Corps School of Aviation Safety provides access to a variety of information resources including its mission statement, class schedules and course descriptions. It also provides access to aviation safety related information including aircraft engine cost data, human factors tools and various safety checklists and instructions. A number of full text papers are available covering topics such as stresses and strains on aircraft, helicopter dynamic rollover, and a series of visual examples of various structural failure modes. Current research areas are described and there are many links to other aviation safety related sites.

University of Glasgow : Department of Aerospace Engineering

This is the home page of the research groups of the Department of Aerospace Engineering at the University of Glasgow. Each of the six groups provides background information about its activities and interests including research projects currently being undertaken. Research is based around six core areas - flight dynamics, computational fluid dynamics (CFD), space systems engineering, air traffic management and avionics, low speed aerodynamics and design and structures.

University of Maryland: Alfred Gessow Rotorcraft Center

The Alfred Gessow Rotorcraft Center (AGRC) at the University of Maryland is one of three rotorcraft centers of excellence established by the Army Research Office (ARO) in 1982. The site provides access to a range of information including: news items, a list of the faculty and their research interests, and a description of the Center's facilities. The research interests of the Center include: rotor dynamics and smart structures; aerodynamics, active and passive damping control of smart structures; damage detection and health monitoring; CFD and acoustics; flight mechanics and controls; and composite structures. References to staff research papers are listed under some of the research sections. the website also as link to the award winning design of the AHS annual student design competion.

Vacuum Assisted Resin Transfer Molding (VARTM) : Model Development and Verification

This is a Virginia Polytechnic Institute and State University Department of Engineering Science and Mechanics PhD dissertation, by Xiaolan Song, dated April 14, 2003. It describes the development and verification of a comprehensive Vacuum Assisted Resin Transfer Molding (VARTM) process simulation model. The model incorporates resin flow through the preform, compaction and relaxation of the preform, and viscosity and cure kinetics of the resin. The computer model can be used to analyze the resin flow details, track the thickness change of the preform, predict the total infiltration time and final fiber volume fraction of the parts, and determine whether the resin could completely infiltrate and uniformly wet out the preform. VARTM of two flat composite panels was conducted to verify the simulation model. The composite panels were fabricated using the SAERTEX multi-axial warp knit carbon fiber fabric and SI-ZG-5A epoxy resin. The simulation code was also used to investigate the VARTM of a new form of sandwich structure with through-the-thickness reinforcements, which is being considered for use in primary aircraft structure. The infiltration of three foam core sandwich preforms with different stitch densities was studied. The objective of the study was to determine whether the preforms could be completely infiltrated and how the stitch density affects the infiltration process. The visualization experiments were conducted to verify the simulation. Bibliographic and abstract details are available in HTML format. The full text of the document is accessible online in PDF format [3.54 Mb]. This title is part of Virginia Tech�s Electronic Thesis and Dissertation Collection (VT ETD)

Verification of the Combined Load Compression (CLC) Test Method : Final Report

This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-00/26, by Peter M. Wegner and Donald F. Adams, dated August 2000. The reports examines a Combined Loading Compression (CLC) test method for the determination of lamina compressive strength and modulus, which has been developed by the University of Wyoming. The full text of the report is available in PDF format, from the FAA's Office of Aviation Research web site.

Vibration Analysis of Cracked Composite Bending-torsion Beams for Damage Diagnosis

This is a Virginia Polytechnic Institute and State University Department of Mechanical Engineering PhD dissertation, by Kaihong Wang, dated , November 29, 2004. It describes the development of an analytical model of cracked composite beams vibrating in coupled bending-torsion. Based on the crack model, the aeroelastic characteristics of an unswept composite wing with an edge crack are investigated. The cracked composite wing is modelled by a cracked composite cantilever and the inertia coupling terms are included in the model. An approximate solution on critical flutter and divergence speeds is obtained by Galerkin�s method in which the fundamental mode shapes of the cracked wing model in free vibration are used. model-based crack detection (size and location) by changes in natural frequencies is addressed. The Cawley-Adams criterion is implemented and a new strategy in grouping frequencies is proposed to reduce the probability of measurement errors. Finally, sensitivity of natural frequencies to model parameter uncertainties is investigated. Uncertainties are modeled by information-gap theory and represented with a collection of nested sets. Five model parameters that may have larger uncertainties are selected in the analysis, and the frequency sensitivities to uncertainties in the five model parameters are compared in terms of two immunity functions. Bibliographic and abstract details are available in HTML format. The full text of the document is accessible online in PDF format [1.88 Mb]. This title is part of Virginia Tech�s Electronic Thesis and Dissertation Collection (VT ETD)

Widespread Fatigue Damage in Military Aircraft

This is Research and Technology Organization (RTO) AGARD Conference Proceedings report, AGARD-CP-568, dated December 1995. Several countries have been experiencing aging air craft related problems in their military fleets, p articularly among their military transport aircraf t. The most troubling aging aircraft structure-rel ated issue is widespread fatigue damage (WFD), som etimes termed as multiple site damage, whose onset due to fatigue causes a dramatic structural stren gth reduction. Invariably, when WFD occurs, the af fected model in the fleet is subjected to an exten sive modification program which is almost always e xpensive and time-consuming. A Specialists' Meetin g on the subject was held in order to explore ways and means to quantitatively predict structural de gradation on account of WFD as a function of usage and when WFD is likely to occur. For individual titles, see N96-24260 through N96-24277. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (48 Kb) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library.

Wright Air Development Center Digital Collection

Wright-Patterson Air Force Base has been a major centre of aeronautical and aeorspace design and development for many years. The purpose of this site is to document various aspects of the Wright Air Development Center (WADC) period in this long history. The site, which is hosted by the Galvin Library at Illinois Institue of Technology, provides access to a range of information resources. The history section includes a timeline of important events; image gallery, an overview of WADC's association with Illinois Institute of Technology; and features on the Center's involvement in both the "space race" and the Roswell incident. The reference shelf contains a linked bibliography of historical sources relating to the Wright Air Development Center. Some of these publications, such as, Birthplace, Home and Future of Aerospace... The Evolution of Aeronautical Development at the Aeronautical Systems Center, are available in full text (pdf format). The Digital Collection provides access to WADC technical report information. The collection can be browsed by report number, date, author or corporate author. Many of the reports are available in full text. A full bibliography of reports is also available in pdf, MS Excel, or interactive (requires Internet Explorer v. 4.01 and Microsoft Office Web Components) formats.

Xcalcs : Online Calculations for Structural Engineers

The web site provides access to a set of calculation forms and software tools for engineering structural analysis, which can be used online via a simple user interface. The basic service is free, but users are requested to register, and additional functionality is available to subscribers. There are tools covering a number of structural engineering problems including: beams (for example, simple bending, bending and compression, bending and tension, held ends); pipes; plates; and vessels (eg shell structures). User instructions are available and there is an example provided.

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