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Metals 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, 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. 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. Aircraft Materials Fire Test Handbook This web site provides access to a Federal Aviation Administration Report titled: Aircraft Materials Fire Test Handbook, compiled by April Horner, DOT/FAA/AR-00/12, April 2000. The handbook describes all FAA-required fire test methods for aircraft materials. The appendices contain the following: FAA fire safety regulations; FAA approval processes; aircraft materials; regulatory methodology used by other countries; aircraft industry internal test methods and guidelines; laboratories actively using fire test methods, and commercial manufacturers of fire test equipment. The full text of the handbook is available online in PDF format. Aluminum Alloy Forgings This is Research and Technology Organization(RTO) AGARD Advisory Report, AGARD-AR-353, dated May 1998. Historically, many aluminum aircraft components have been made from forgings. However, to reduce airframe manufacturing cost aircraft manufacturers are converting to parts machined from thick plate. The results of recent research indicates that forgings often offer significant advantages over components machined from plate. The purpose of this report is to present this information. The document is contained in the RTO's Full Text Publication Library. Bibliographic details and an abstract are available in HTML format. The full text can be accessed online in PDF format from the RTO's web site. Analysis and Simulation of Hypervelocity Gouging Impacts This is the full text of a Doctoral thesis by Major John D. Cinnamon, USAF, AFIT/DS/ENY/06-01, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in June 2006. In this work, a summary of past and present research efforts, as well as the theoretical foundation, of hypervelocity gouging is presented. As the Holloman AFB High Speed Test Track (HHSTT) sled's speed has increased to Mach 8.5, material interactions develops which causes "gouging" - this can result in catastrophic failure. A characterization of gouging, including a thermodynamic history, is developed from an examination of a gouged rail. An extensive study is performed that determines the specific material flow models for VascoMax 300 and 1080 steel. The models are validated utilizing several experimental tests which are successfully simulated using CTH - a state-of-the-art shock wave physics hydrocode. Additionally, a penetration theory is developed which provides insight into the gouging problem using an analytic approach that does not require the use of computationally intensive codes. Based on the detailed examination of the materials and the validation of the material models within CTH, an evaluation of the HHSTT gouging phenomenon is performed. These simulations of the gouging problem replicate the experimentally observed characteristics and lead to recommendations to mitigate the occurrence of hypervelocity gouging. [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). 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). Application of Functionally Graded Materials in Aircraft Structures This is the full text of a Master's thesis by Captain William G. Cooley, USAF, AFIT/GAE/ENY/05-M04, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2005. A Functionally Graded Material (FGM) is a material which has a continuous variation of material properties through-the-thickness. This thesis will explore analysis of FGM flat plates and shell panels, and use FGM's unique characteristics to retrofit a cracked exhaust wash structure. FGMs are first characterized as flat plates under pressure and thermal loading. Next, FGM shell panels are characterized under thermal loading. Conclusions drawn from FGM characterization are used to develop a patch to retrofit a cracked aircraft exhaust wash structure. The exhaust wash structure is first analyzed to provide a baseline and then several FGM patches are evaluated on their ability to reduce stress and deflection. Finally, an exhaust wash panel made of FGM is analyzed. [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). 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. Archaeological Silver Embrittlement: A Metallurgical Inquiry This technical report (NLR-TP-2002-224) was published by the NLR (the National Aerospace Laboratory of the Netherlands) in 2002 and was written by R. J. H. Wanhill. Some archaeological silver artifacts and coins are found to be brittle. The brittleness is due to long-term corrosion and microstructural changes. Recognition and determination of corrosion-induced and microstructurally-induced embrittlement, and also their synergy, are important for restoration and conservation of ancient and historic silver. This report is concerned mainly with defining and explaining the types, probable mechanisms and severity of embrittlement, based on current metallurgical knowledge and concepts. It also includes surveys of the diagnostic techniques for determining embrittlement and the possible remedial measures to be taken. Corrosion may be general, forming a brittle surface layer. But it can also penetrate the metal along grain boundaries, segregation bands, interdendritic regions (in cast objects), and slip lines and deformation twin boundaries in objects containing remanent cold-work. The probable and possible mechanisms of corrosion-induced embrittlement include galvanic attack owing to long-term low temperature segregation of copper to grain boundaries (discontinuous or cellular precipitation), galvanic attack owing to the presence of the remains of high temperature segregation of copper, and preferential stress- and strain-assisted corrosion along slip lines and deformation twin boundaries. Microstructurally-induced embrittlement is characterized by grain boundary fracture, which is most likely due to impurity elements segregating to grain boundaries and reducing their cohesive strength. Empirical evidence, empirical and theoretical concepts of segregation-induced embrittlement, and consideration of the impurity elements in archaeological silver result in identifying lead as the most likely perpetrator, with bismuth, arsenic, thallium, antimony and tin as increasingly less likely additional candidates. The severity of both kinds of embrittlement is increased by the synergistic action of corrosion-induced and microstructurally-induced embrittlement and a larger grain size. The effect of grain size is explained and semi-quantitatively assessed using micromechanical models of corrosion-induced, microstructurally-induced and synergistic embrittlement. These models consider the interactions between microcracks, lattice dislocations and grain boundaries, and are shown to make a general prediction of the grain size effect. The last main sections of the report give the surveys of diagnostic techniques and remedial measures. The diagnostic techniques can be well specified. They include visual inspection, X-ray radiography, optical and SEM metallography (the latter combined with EDX or WDX chemical analysis), microhardness testing and SEM fractography. The most definitive technique, with the broadest diagnostic scope, is SEM metallography. The remedial measures that could or should be taken during restoration and conservation ( particularly restoration ( are less certain. Suggested remedies are intended to be used as a guide, whereby each case has to be considered on its own merits. The report ends with a number of conclusions and suggestions for further research. [Taken from abstract]. The full text is available as a PDF file. 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. ATI Allvac This company produces nickel-base and cobalt-base superalloys, titanium-base alloys, and speciality steels for the aerospace industry. In particular the site provides detailed specifications for each of the company's products, including nominal composition and mechanical properties. Technical data sheets in HTML or PDF format are also available and provide further information such as physical properties, heat treatment, hardness, forgeability, machinability and weldability. Ballistic Experiments With Titanium and Aluminum Targets : Final Report This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-01/21, by Raymond P. Gogolowski and Bruce R. Morgan, dated April 2001. The report describes experiments in penetration mechanics on 6Al-4V titanium and 2024-T3 aluminium. The purpose of the tests was to determine the ballistic speed limits of the two alloys, and the failure modes of the projectiles and targets. The full text of the report is available in PDF format from the online catalogue of the FAA William J. Hughes Technical Center Library. Battle Damage Modeling
This is the full text publication that was assembled to support a Lecture Series under the sponsorship of the Applied Vehicle Technology Panel (AVT) presented on 17-18 May 2010 in Prague, Czech Republic. Biaxial Fatigue Behavior of Niti Shape Memory Alloy This is the full text of a Master's thesis by First Lieutenant Daniel M. Jensen, USAF, AFIT/GA/ENY/05-M06, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2005. Nitinol is a shape memory alloy (SMA) capable of martensite-to-austenite phase transformations enabling shape-memory behavior. Shape-memory properties make Nitinol a strong candidate material for use in aircraft applications such as actuators. Structural integrity and reliability of torque tube actuators must be assured before this material can be used in flight-critical components. Thorough understanding of the fatigue response of the material is essential for a structurally-sound SMA actuator design. The present effort investigates pure torsion and combined tension-torsion fatigue behavior of Nitinol at room temperature. Monotonic tests in tension and torsion were conducted to typify uni-directional stress-strain behavior. Fully-reversed torsion fatigue tests were conducted with shear stress ranges of 416, 584, 674, and 1310 MPa. In fully-reversed biaxial fatigue tests, a shear stress range of 500 MPa was superimposed on the axial stress ranges of 250, 500, 1000, 1120, and 1500 MPa. Fatigue behavioral characteristics, including fatigue S-N curves were established. Fatigue lives obtained in torsion-dominated biaxial tests were similar to those obtained in pure torsion. Conversely, tension-dominated biaxial fatigue was significantly more damaging, resulting in decreased fatigue lives. Applicability of von Mises criterion to correlating uniaxial and biaxial test results was examined. Evolution of stress-strain behavior with cycling is discussed. [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). Brittle Archaeological Silver : A Fracture Mechanisms Assessment This technical report (NLR-TP-2001-369) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2001 and was written by R.J.H. Wanhill. Archaeological silver may be embrittled by long-term corrosion and microstructural changes. The embrittlement increases with increasing grain size, and the combination of a large grain size with synergistic embrittlement (conjoint action of corrosion-induced and microstructurally induced embrittlement) is particularly detrimental. Micromechanical models of cracking that incorporate the grain size provide insight into the severity of embrittlement. Severely embrittled artifacts are frangible or even friable. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it. Characterisation of Fibre Reinforced Titanium Matrix Composites This is Research and Technology Organization (RTO) AGARD-R-796, dated February 1994. The combination of stiffness, strength, and high temperature resistance provided by fiber reinforced titanium matrix composites offers major benefits for aircraft engine and airframe applications, where these materials could be used to reduce weight or improve performance. This workshop on the subject of characterization of titanium composites was intended to provide a forum for the exchange of information in this important area. Characterization in this case refers to the understanding of the behavior of the composites as it relates to the ability to predict their performance in real-life applications. It covers various topics that include mechanical test techniques, NDE methods, life prediction models, and other factors that will affect the level of confidence with which these relatively new materials will be accepted for application. For individual titles, see N94-36650 through N94-36670. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (79.74MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library. Characterization of Early Stages of Corrosion Fatigue in Aircraft Skin Phase II : Interpretation of Corrosion-Fatigue Fracture Surfaces in Alclad 2024-T3 Aluminum Alloy Sheet This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-99/34, by C.G. Schmidt, T. Kobayashi, and D.A. Shockey, dated May 1999. The report examines the fracture surface topography produced in the early stages of corrosion fatigue and the effect of environment on the crack nucleation mechanism based on fracture surface features. It also describes a series of tests on bare and clad 2024-T3 sheet in various environments to assess the effects of environment, stress, and material condition on nucleation and early propagation kinetics of corrosion fatigue cracks. The full text of the report is available in PDF format from the online catalogue of the FAA William J. Hughes Technical Center Library. 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. Chris Heintz Design College This web site brings together a number of full text articles that deal with various aspects of light aircraft design. Fourteen of the articles were published in the Experimental Aircraft Association's (EAA) Light Plane World or Experimenter publications. The topics covered include: light aircraft materials and their properties; flight and performance testing; riveted joints; airfoils; pitch, stability and control; control surfaces; determining weight and balance; and STOL aircraft design. The author, Chris Heintz, is resonsible for the design of a range of kit aircraft for the Zenith Aircraft Company. 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. 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 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. Creep Behavior Of Thin Laminates Of Iron-Cobalt Alloys For Use In Switched Reluctance Motors And Generators This is the full text of a PhD thesis by Richard Todd Fingers, which was presented to the Faculty of the Virginia Polytechnic Institute and State University in 1998. The United States Air Force is in the process of developing magnetic bearings as well as an aircraft Integrated Power Unit and an Internal Starter/Generator for main propulsion engines. These developments are the driving force behind a new emphasis on high temperature, high strength magnetic materials for power applications. Analytical work, utilizing elasticity theory, in conjunction with design requirements, indicates a need for magnetic materials to have strengths in excess of 80 ksi up to about 1000 degrees F. It is this combination of desired material characteristics that is the motivation for this effort to measure, model, and predict the creep behavior of such advanced magnetic materials. [Taken from abstract]. The full text of the thesis is available in PDF format. Damage Identification in a Real Structure Using Resonant and Anti-Resonant Frequencies The site provides access to an Air University Air Force Institute of Technology MSc Thesis by Captain Douglas E. Gaeta, USAF, dated March 2000. The thesis describes the development and testing of a number of damage and detection algorithms for the Air Force Institute of Technology's Flexible Truss Experiment (FTE), which is intended to be representative of a large space structure. Citation details and an abstract are available in HTML format. The full text can be accessed in PDF format (2,460,251 bytes). The document is part of the Air University Research Database. Defense Advanced Research Projects Agency (DARPA) : Microsystems Technology Office (MTO) The MTO is one of eight technical offices in DARPA. It is concerned with the development, demonstration and transition of key solid state technologies. The web site lists contacts, describes MTO programmes, and provides links to the text of open and closed solicitations. The publications section provides access to the report of a Chemical and Biological Sensor Standards Study. The archives section contains details of past programmes, solicitations, workshops and publications. Deformation Modelling of the Single Crystal Superalloy CM186 LC This technical report (NLR-TP-2002-597) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2002 and was written by R. Daniel, T. Tinga, M. B. Henderson and T. J. Ward. Single crystal nickel-based superalloys are being used increasingly to manufacture the turbine blades for both aero and land-based gas turbine engines. These alloys provide significant increases in component endurance and reliability, as well as engine performance due to the increased turbine entry temperature levels that can be achieved. To ensure full utilisation and determination of safe component lifetimes, accurate modelling of the non-linear deformation suffered during typical duty cycles is needed. In recent years a number of anisotropic creep data analysis and modelling methods have been developed, largely based on the determination of constitutive parameters for the <001> and <111> crystallographic directions. These models have been incorporated within a Schmid's Law slip-system analysis to determine local shear creep strain accumulation and resolved shear stresses. Any appropriate creep formulation can be included within this framework. The present paper describes the development of two models: i) the QinetiQ Creep Law and ii) the creep law used by the National Aerospace Laboratory (NLR) in The Netherlands, that have been incorporated into user material subroutines for the ABAQUS and MSC Marc finite element programmes, respectively. The models allow full three-dimensional analysis with elastic, plastic, creep and thermal deformations capable of simulating the high temperature creep and thermomechanical fatigue behaviour of specimens and turbine blades under service loading conditions. Predictions have been generated for the anisotropic creep behaviour of a number of specimen tests and blade designs for the as-cast (non-solutioned) single crystal nickel based superalloy CM186LC. [Taken from abstract]. The full text is available as a PDF file. 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. Design of Repair for Battle Damaged Rotary Wing Aircraft
This is the full text publication that was assembled to support a Lecture Series under the sponsorship of the Applied Vehicle Technology Panel (AVT) presented on 17-18 May 2010 in Prague, Czech Republic. Design of Repair of Battle-Damaged Fixed-Wing Aircraft
This is the full text publication that was assembled to support a Lecture Series under the sponsorship of the Applied Vehicle Technology Panel (AVT) presented on 17-18 May 2010 in Prague, Czech Republic. Determination of the Constitutive Equations for 1080 Steel and VascoMax 300 This is the full text of a Master's thesis by Ensign Zachary A. Kennan, USN, AFIT/GAE/ENY/05-J05, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in June 2005. The objective of this research is to establish a better representation of the components utilized in a gouging event being considered in research leading to a better understanding of the Holloman High Speed Test Track. Gouging occurs when two metals are traveling at a slight incline to each other at velocities nearing 1.5 kilometers per second, and results in a structural failure of both the metals. The gouging process occurs at very high strain rates, which results in non-linear stress-strain relations. The coefficients that lead to the Johnson-Cook equations have been determined by the Split Hopkinson Bar test for 1080 steel and VascoMax 300. The Split Hopkinson Bar test was conducted using various strain rates and temperatures to produce meaningful stress-strain relations for both of the steels. These relations allowed a fit of the data to yield specific material coefficients defined in the Johnson-Cook constitutive model. Both the 1080 steel and Vascomax 300 models showed excellent approximation of the plastic region. Verification of the constitutive models was conducted through the use of Taylor tests. A Taylor test model utilizing the constitutive equations was developed in CTH and produced deformation profiles that closely resembled specimens taken from experimental Taylor tests. The end result of this work will be utilized in further studies toward overall high energy impact evaluation. [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). Directory of organizations, investigators, and programs in high temperature corrosion research This is Research and Technology Organization (RTO) AGARD-R-585, dated August 1971. This directory of research organizations, investigators, and research programs or areas of research was prepared from information gathered by the NATO/AGARD Working Group on Basis and Appied Research on High-Temperature Corrosion, and the European Federation of Corrosion’s Working Group on Corrosion by Hot Gases and Products of Combust ion. There are 178 organizations from eleven NATO countries included. A category index indicates the high-temperature corrosion research areas in which, the various organizations are conducting research. The two research areas currently receiving the most attention are: 1. material behaviour under corrosion and 2. reaction kinetics and diffusion processes, in which 119 and 97 organizations, respectively, are working. An alphabetical index of investigators includes approximately 240 names. The directory lists the organization, together with the investigators and the research areas (or specific programs) in which they are working, alphabetically by countries. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (3.97 MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library. Effect of Damage on Strength and Durability
This is the full text publication that was assembled to support a Lecture Series under the sponsorship of the Applied Vehicle Technology Panel (AVT) presented on 17-18 May 2010 in Prague, Czech Republic. This is a report by the Research and Technology Organisation (RTO) of NATO. The author is Mohan M. Ratwani, Ph. D at R-Tec in the USA. Effects of Concentrated Hydrochloric Acid Spills on Aircraft Aluminium Skin Produced by the William J. Hughes Technical Center of the Federal Aviation Administration (FAA), this report is technical note DOT/FAA/AR-TN97/108. Written by Louise C. Speitel, it is dated July 1998. This document describes the tests conducted to evaluate the effects of a spill of a strong corrosive acid such as hydrochloric acid (HCl) on aircraft interior skin and to determine the time required for a spill of Department of Transportation (DOT) allowable volumes and concentrations to cause catastrophic failure. This is a .pdf file [13 pages, 192Kb] so you will need Adobe Acrobat software in order to read it. Effects of Foreign Object Damage From Small Hard Particles on the High-Cycle Fatigue Life of Ti-6Al-4V The site provides access to an Air University Air Force Institute of Technology Research Report, by Major Joseph L. Hamrick, II, dated 2000. The report examines high-cycle fatigue behaviour of fan and compressor blades when subjected to foreign object damage. It presents the results of a series of laboratory tests on specimens of Ti-6Al-4V involving glass and steel spheres of different diameters; quasi-static displacement controlled indentation using steel chisels with different radii; and shearing notches with a constant radius chisel point under quasi-static loading. Citation details and an abstract are available in HTML format. The full text can be accessed in PDF format (22,928,892 bytes). The document is part of the Air University Research Database. Effects of Phase Difference Between Axial and Contact loads on Fretting Fatigue Behavior of Titanium Alloy This is the full text of a Master's thesis by Lieutenant-Colonel Mohammad Almajali, Royal Jordanian Air Force, AFIT/GAE/ENY/06- S02, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in September 2006. Fretting fatigue is the surface damage that occurs at the interface between two components that are undergoing a small amplitude oscillatory movements. It results in a reduction of the material life as compared to the plain fatigue. Most of the previous works were accomplished under a constant applied normal load and a little effort was done under a variable contact load, while none of these studies has considered the phase difference between the axial load and the contact load. The primary goal of this study is to investigate the effect of phase difference between axial and contact loads on fretting fatigue behavior of Ti-6Al-4V alloy. The frequency of both axial and contact loads was the same. i.e. 10 Hz. Under variable contact load condition; only the axial stress range and the phase angle were varied. Cracks were always found to initiate at the contact surface and near the trailing edge in all tests. The software program, ABAQUAS, was used in Finite Element Analysis FEA to determine the contact region state variables such as stress, strain, and displacement. The fatigue parameters; such as the stress range, effective stress, and modified shear stress range (MSSR) were analyzed to predict the fatigue life. The fatigue life with in-phase variable contact load was almost same as that of constant contact load. The out of phase condition increased the fatigue life from 20% to 30% in the low cycle regime and up to 150% in the high cycle regime relative to its counterpart from in-phase loading. The MSSR parameter, a critical plane based fretting fatigue parameter, was very effective in predicting the fatigue life, crack initiation location, and the crack initiation orientation. [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). Effects of Shot-Peening on High Cycle Fretting Fatigue Behavior of Ti-6AL-4v This is the full text of a MSc thesis by Halil I. Yuksel which was presented to the Graduate School of Engineering and Management of Air University's Air Force Institute of Technology (AFIT), in March 2002. It is available in PDF format. Abstract: Effects of shot-peening on high cycle fretting fatigue behavior of Ti-6Al-4V were investigated. S-N curves were obtained with 6.35 mm thick specimens. Scanning Electron Microscopy showed that for 6.35 mm thickness, cracks initiated on the contact surface whereas the crack initiation location was found to be at the depth ranging from 200 to 300 microns from the contact surface for 3.81 mm thick specimens tested in a previous study at AFIT. The orientation of the primary crack for 6.35 mm thickness was around -37 degrees, and the orientation of the secondary crack was around -28 degrees. Failure location was near the trailing edge of contact for both thicknesses. Commercially available finite element code ABAQUS was used to analyze the specimens. Axial stress (Oxx) distribution along the longitudinal direction and within depth of the specimen was found to determine where the stress concentration was maximum that may have caused crack initiation. Maximum stress concentration was found in the trailing edge of contact where the specimens failed. Also transverse ( ), and shear ( ) stresses were found. Using Oxx, Oyy, and xy values of FEA output data, Smith-Watson-Topper, Findley, Shear Stress Range and Modified Shear Stress Range ( MSSR ) parameters were evaluated. Stress relaxation was observed after the failure of specimens, and based on specific assumptions about stress relaxation, evaluations were repeated for different percentages of stress relaxation. MSSR Parameter was determined to be the only appropriate fatigue parameter that could meet all the required conditions for shot-peened specimens. Also, thickness effects on shot-peened specimens were investigated and discussed in this study. Effects of Temperature and Shot-Peening Intensity on Fretting Fatigue Behavior of Titanium Alloy TI-6AL-4V This is the full text of a Master's thesis by First Lieutenant Salman Albinali, RBAF, AFIT/GAE/ENY/05-M25, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2005. Effects of temperature and shot-peening intensity on fretting fatigue behavior of Ti-6Al-4A were investigated in this study. S-N curves were obtained for both room and elevated temperatures (260 C) for two different shot-peened intensities (4A and 10A). Stress relaxation behavior under both fretting fatigue at elevated temperature and temperature exposure only were also investigated after their measurements were calculated using X-ray diffraction method. The crack initiation location and the crack angle orientation along the surface were determined using optical and scanning electron microscopy (SEM). Cracks initiated near the trailing edge of the tested specimens. Cracks initiated on the contact surface for both specimens with 4A and 10A shot-peened intensities at elevated temperature. Finite element analysis was preformed by commercially available software, ABAQUS, to obtain contact region state variables such as stress, strain and displacement. Those state variables were needed for the computation of fretting fatigue parameters. Fatigue parameters, such as stress range, effective stress and modified shear stress range (MSSR), were analyzed. It was found that there was relaxation of residual compressive stress during fretting fatigue at room and elevated temperature, greater stress relaxation occurred when higher temperature was applied. Also, both 4A and 10A specimens had the same percentage of residual stress relaxation due to temperature exposure only. Further, elevated temperature conditions negate the effect of shot-peening, thereby providing no improvement in fatigue life. On the other hand shot-peening at room temperature conditions improved fatigue life due to shot-peening. Both shot-peening intensities at room temperature provided an improvement to fatigue life with the 10A providing the greatest extension to fatigue life. [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). Electronic Materials and Devices : Report of the Defence and Aerospace National Advisory Committee The National Advisory Committee (NAC) on Electronic Materials and Devices was established in 1999 in order to develop and communicate an understanding of the needs and priorities for research and technology development, to maintain a view of UK competitiveness, and to advise the Defence, Aerospace and Systems (DASP) foresight panel on electronic materials and devices. This report, published in March 2002, focuses on seven topic areas: Silicon, Compound Semiconductors, Interconnection and Packaging, Electro-Optics and Displays, Sensors and Microsystems, Nanotechnology, and Non-Semiconductor Electronic Materials. The text of the report is available in HTML 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. Evaluation of Cold Dwell Fatigue in Ti-6242 This provides access to a Federal Aviation Administration (FAA) report DOT/FAA AR-06-24 by Somnath Gosh ...[et al] dated February 2007. The primary objective of this research was to develop a fundamental understanding of the mechanical and metallurgical factors that cause earlycrack initiation under dwell-fatigue conditions in Ti-6Al-2Sn-4Zr-2Mo (+Si) alloy. Materials examined in this study have the representativelamellar and globular alpha/beta microstructures.The study combined experiment with detailed solid mechanics analysis to produce a semiquantitative understanding of the processes that lead tofatigue crack initiation under dwell-loading conditions. Time-dependent flow behavior was incorporated into the constitutive relations used tomodel the material behavior during dwell loading. A variety of state-of-the-art experimental methods were used to support the analytical workand to provide detailed characterization information regarding the nature of dwell-initiated fatigue cracks.The key analytical finding was that significant internal load redistribution occurs from soft to hard regions when time dependence isincorporated into the analysis. Here, soft and hard refer to the orientation dependence of the flow stress in the hexagonal alpha phase. Detailedexaminations of the dwell-fatigue crack origins show that they lie close to but do not coincide with the basal planes. The precise orientation ofthese cracks was determined experimentally. Very small cracks were located using acoustic microscopy and microradiography. These crackswere excised and characterized in detail, including the local orientation dependence of the flow stress of regions surrounding the crack. The sizeof the hard regions where the crack initiates were measured using a quantitative technique.Experts in the field have suggested that hydrogen has an influential role in dwell fatigue. Consequently, the effect of variation in hydrogencontent on dwell fatigue was examined by testing hydrogen-charged specimens. The results indicated that for the continuous alpha phasemicrostructure, the dwell-fatigue life is higher for higher hydrogen contents, especially for hydrogen contents > 150 ppm.This report describes the detailed associated information obtained during the course of this research, including the novel experimental methodsused to obtain them. It also contains a number of appendices which contain more detailed data and results. [Taken from abstract]. The full text is available in PDF format from the online catalogue of the FAA William J.Hughes Technical Center Library. Evaluation of Factors Contributing to Damping of Coated and Uncoated Titanium Plates This is the full text of a Master's thesis by Second Lieutenant Dustin W. Lee, USAF, AFIT/GA/ENY/06-M06, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2006. High Cycle Fatigue (HCF) is the leading cause of component failure in gas turbine engines today, which poses great risk to aircraft, engines, and their crews. Mitigation of HCF effects has become a priority topic, and the damping benefits of hard coatings are being reevaluated for this purpose. Research was conducted to further understanding of damping measurements on these coatings. This study continues work to characterize the damping effects of a magnesium aluminate spinel (mag spinel) coating applied to a titanium plate via vibration testing. Two different plate sizes were evaluated in a clamped-free-free-free condition and a free-free-free-free condition, respectively. In both the clamped and free studies, the second bending and two-stripe mode shapes were identified and studied. Clamped specimens were tested in order to determine various factors affecting damping. Using these factors, it was shown that air damping has a statistically significant impact on damping, where the impact is dependent on mode shape. The amount of damping introduced by the air was, however, minute compared to the losses introduced by the constraint blocks. Testing on free condition specimens explored another possible method to obtain a damping comparison between coated and uncoated samples with fewer damping losses. [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). 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). Examination of Contact Width on Fretting Fatigue This is the full text of an MSc thesis by Russell S. Magaziner which was presented to the Graduate School of Engineering and Management of Air University's Air Force Institute of Technology (AFIT), in March 2002. It is available in PDF format. Abstract: The primary goal of this study was to find the effects on the fretting fatigue life when systematically holding the fretting fatigue variables, peak contact pressure, maximum/minimum nominal bulk stress, and the ratio of shear traction to pressure force constant while varying the contact semi-width through changes in pad radius and normal load. Experimental tests were performed on a test setup capable of independent pad displacement. Analytical and finite element simulations of the different experimental tests were performed. The local mechanistic parameters were inspected. Five different critical plane based fatigue predictive parameters lacked effectiveness in predicting changes in life with changes in contact width. The Ruiz parameter, and a modified version of the Ruiz parameter performed better than the five critical plane based parameters. Correlations between slip amplitude and fretting fatigue life were found. Tests experiencing infinite fatigue life, in contrast to the typical shortened fretting fatigue life, were experiencing the gross slip condition, which led to fretting wear instead of fretting fatigue. Experimental Investigations of Material Models for Ti-6Al-4V Titanium and 2024-T3 Aluminum : Final Report This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-00/25, by Donald R. Lesuer, dated September 2000. The report describes studies of the deformation behaviour of Ti-6Al-4V titanium and 2024-T3 aluminium. Test data, plus additional information from the literature, were used to critically evaluate the Johnson-Cook material model to represent the deformation and failure response of the two alloys under conditions relevant to conditions of engine containment and the influence of uncontained engine debris 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. 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. 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. Fatigue Response of Thin Stiffened of Aluminum Cracked Panels Repaired With Bonded Composite Patches The site provides access to an Air University, Air Force Institute of Technology, Graduate School of Engineering and Management, MSc Thesis, by Captain Jason B. Avram, USAF, AFIT/GMY/ENY/01M-01, dated March 2001. The thesis presents an investigation of the fatigue response of precracked and patched 2024- T3 Aluminum panels with stiffeners. 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 Fire- and Smoke-Resistant Interior Materials This web site provides access to the full text of: Fire- and Smoke-Resistant Interior Materials for Commercial Transport Aircraft, by the Committee on Fire and Smoke Resistant Materials for Commercial Aircraft Interiors, National Research Council, 1996. The two principal objectives of this study were: to identify promising materials technologies, design issues (both overall and for individual components) and fire performance parameters (both full scale and for individual components) that, if properly optimized, would lead to improved fire and smoke resistance of materials and components used in aircraft interiors; and to identify long-range research directions that hold the most promise for producing predictive modeling capability, new advanced materials and the required product development to achieve totally fire-resistant interiors in future aircrafts. The text is available online in Open Book format. There is also an executive summary in HTML format. Fretting Fatigue Behavior of a Titanium Alloy Ti-6AL-4V at Elevated Temperature This is the full text of a thesis by Onder Sahan which was presented to the Air Force Institute of Technology (AFIT) in 2002. Fretting fatigue crack initiation in titanium alloy, Ti-6Al-4V, at elevated temperature is investigated experimentally and analytically using finite element analysis. The temperature of this study is chosen to be 260 oC. Several specimens are tested at different stress levels to establish the life data (i.e. S-N relationship). The crack initiation location and the crack angle orientation along the contact surface are determined using scanning electron microscopy. Finite element analysis is used to obtain the stress states for the experimental conditions used during the fretting fatigue tests. These are then used to investigate several critical plane based multi-axial fatigue parameters. These parameters are evaluated based on their ability to predict the crack initiation location, crack orientation angle along the contact surface, and the number of cycles to fretting fatigue crack initiation. These predictions are compared with their experimental counterparts to characterize the role of normal and shear stresses on fretting fatigue crack initiation at elevated temperature. Also, plain and fretting fatigue data at room and elevated temperature are compared. From these comparisons, it can be concluded that 260 temperature does not have any detrimental effect on fretting fatigue crack initiation of Ti-6Al-4V when compared to that at room temperature. Further, fretting fatigue crack initiation mechanism in the tested titanium alloy appears to be governed by the shear stress on the critical plane. However, further work is needed to understand the role of both shear and normal stresses on the critical plane at elevated temperatures. [Taken from abstract]. The full text is avialable in PDF format and is provided by the Air University ResearchWeb site. Fretting Fatigue Behavior of Nickel Alloy IN-100 This is the full text of a Master's thesis by Captain Elhoucine Madhi, RMAF, AFIT/GAE/ENY/06-M22, which was presented to the Faculty Department of Aeronautics and Astronautics of Air University's Air Force Institute of Technology (AFIT), in March 2006. In this study, a systematic investigation of the fretting fatigue behavior of nickel alloy, IN-100 was carried out. The study includes both experimental work and the corresponding analysis of the contact conditions, and the latter is accomplished using the finite element method. Fretting fatigue tests were performed over a wide range of axial stresses to examine both low and high cycle fretting fatigue under constant contact load and the influence of different pad geometries was also explored. It was observed that fretting reduced the fatigue strength of IN- 100, and that increasing cylindrical pad radii does not have the same effect as in titanium-based alloys. The crack initiation location and orientation along the surface were measured using the Optical and Scanning Electron Microscopy (SEM). In all experiments, cracks were found to initiate near the contact zone trailing edge, and at an orientation of 45? with a scatter of 10?. Finite element analysis was conducted through the commercially available software, ABAQUS, to obtain the contact region state variables such as stress, strain and displacement. These state variables were needed for the computation and analysis of fretting fatigue crack initiation parameters which were Findley parameter, Smith-Watson-Topper (SWT) parameter, shear stress range (SSR), and modified shear stress range (MSSR). These parameters were evaluated based on their ability to predict crack location, crack initiation angle and fatigue life without dependence on contact geometry. The comparison of the analysis and the experimental results showed that fretting fatigue life is not only governed by shear stress on the critical plane, but also the normal stresses plays a role in the crack initiation mechanism. After adjusting the constants used in MSSR calculations for Ti-6Al-4V, it was found that MSSR parameter is also capable of predicting crack location, in IN-100. [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). Fretting Fatigue Behavior of Shot-Peened IN 100 This is the full text of a Master's thesis by Second Lieutenant Jonathan L Ng, USAF, AFIT/GMS/ENY/06-M01, which was presented to the Faculty Department of Systems and Engineering Management of Air University's Air Force Institute of Technology (AFIT), in March 2006. The fretting fatigue behavior of shot-peened of IN 100 was investigated in this study. S-N curves were obtained for two different shot-peened intensities (7A and 12A) and were compared to those of unpeened specimens. Stress relaxation behavior under fretting fatigue was also investigated after their measurements were obtained using the X-ray diffraction method. The crack initiation location and the crack angle orientation along the surface were determined using optical and scanning electron microscopy (SEM). Cracks initiated near the trailing edge and on the contact surface for both 7A and 12A shot-peened specimens. Finite element analysis was performed using commercially available software, ABAQUS, to obtain contact region state variables such as stress, strain and displacement. These state variables were needed for the computation of fretting fatigue parameters, such as stress range, effective stress, shear stress range (SSR) and modified shear stress range (MSSR), which were further analyzed. It was found that there was relaxation of residual compressive stress during fretting fatigue up to a certain depth. The effects of shot-peening were negated relatively early in the fretting fatigue life. There was little difference in fretting fatigue life between the two intensities of shot-peening, but there was an improvement in relation to unpeened specimens. Also, the MSSR parameter, a critical plane based fatigue parameter, was effective in characterizing the fretting fatigue behavior in terms of fatigue life, crack initiation location and orientation. However, it is not applicable to both shot-peened and unpeened cases simultaneously to yield a single trend. This may be due to the peened specimens having been plastically-deformed on the surface and the unpeened specimens remain unchanged, and hence they were two different types of material which did not to act the same way under fretting fatigue conditions. [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). Fundamental Studies: Inspection Properties for Engine Titanium Alloys This technical report (DOT/FAA/AR-02/114) was produced by the Aviation Research Office of the Federal Aviation Administration (FAA) in December 2002 and was written by F. J. Margetan, M. Gigliotti, L. Brashe and W. Leach. Titanium alloys are widely used in critical rotating components for jet engine applications. Because of the important role they play in overall flight safety, it is important that the components be free of defects which can lead to failure. In light of this requirement, titanium components are typically inspected several times during the production process. One of the methods used is ultrasonic inspection. However, titanium is an ultrasonically noisy material which can lead to false indications of missed flaws. In an effort to understand the relationship between microstructure and detectability, the Engine Titanium Consortium completed an extensive study of the fundamental properties of titanium materials. This study focused on Ti -6A1 -4V and Ti-17 (Ti-5 wt.% A1-2 wt.% Sn-2 wt.% Zr-4 wt.% Cr-4 wt.% Mo), two common alloys used in jet engine applications. The results of this work provided needed data and samples to other technical tasks in the Engine Titanium Consortium. A summary of the findings is provided in this document. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it. Future Materials Science Research on the International Space Station This web site provides access to a report prepared by the National Research Council's Committee on Materials Science Research on the International Space Station, Washington, D.C., National Academy Press, 1997. The report presents the results of the Committee's evaluation of NASA's high-temperature, microgravity materials research plan. In particular it focuses on the Space Station Furnace Facility (SSFF) Core. This will provide the mechanical, power and control infrastructure for an array of experiment modules designed for crystal growth and solidification research in the fields of electronic and photonic materials, metals and alloys, glasses and ceramics. The report also reviews NASA's selection procedures for identifying and supporting research within the developing field of materials science and engineering. An executive summary is available in HTML format, and the full text of the report can be accessed online in Open Book format. Gamma Prime Precipitation Modeling and Strength Response in Powder Metallurgy Superalloys This web site provides access to a West Virginia University Department of Mechanical and Aerospace Engineering PhD dissertation, by Jian Mao, dated 16 May 2002. The main objective of this research was to study the g precipitation kinetics in various cooling circumstances and also study the strength response to the cooling history in two model nickel-based superalloys, Rne88DT and U720LI. Bibliographic and abstract details are available in HTML format. The full text of the document is accessible online in PDF format. This title is part of West Virginia University's Electronic Thesis and Dissertation Project. 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 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 Cycle Fatigue Behaviour of Intermetallic y-TiAl Based Alloys This technical report (NLR-TP-2002-332) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2002 and was written by M. F. J. Koolloos, D. J. Arrell, M. B. Henderson and S. Gallet. The high cycle fatigue behaviour of two versions of a high strength TiAl-based alloy (ABB-2 and ABB-23) have been investigated. The plain and notched (Kt = 3) axial high cycle fatigue behaviour of ABB-2 has been studied at 20 and 700?der two different R ratios, and that of ABB-23 has been studied at 20(C (R=0.1 and 0.5) and 550?=0.1). The fatigue tests showed flat S-N plots with high fatigue strength to UTS ratios (~1). The notched fatigue strength depended on the colony size relative to the specimen size and was often higher than the unnotched fatigue strength. The fatigue strength of both ABB alloys compare well with trendline data presented for Ti-4722XD however the degree of scatter in the endurance data is often excessive. The increased fatigue strength for ABB-2 and ABB-23 is commensurate with the increased tensile properties of the ABB alloys. After the fatigue tests metallographic investigation of fracture surface cross-sections was carried out to determine the fracture modes and fractography was done to reveal the initiation sites and crack growth directions. It is concluded that although both the ABB alloys show very high fatigue strength relative to their tensile strength, their behaviour strongly depends on the microstructure. [Taken from abstract]. The full text is available as a PDF file. 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 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. Influence of Heat Treatments and Straining Steps on Mechanical Properties in the Stretch Forming Process This technical paper (NLR-TP-2004-266) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2004 and was written by E.N. Straatsma and L. Velterop. In the aerospace industry, stretch forming of heat-treatable aluminium sheet is a widely used forming method. Simulation of the stretch forming process with FEM is helpful to predict the strain distribution in complex products, to find out the limits of the forming process, and to optimize the amount of strain in each step. Therefore, tensile tests are carried out to determine the influence of intermediate annealing in combination with straining steps on the mechanical properties of AA2024 T3. Since multiple stretching steps with intermediate annealing can influence the grain size and cause visible defects, the development of the grain size in AA2024 T3 is also studied. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it. Influence of Wire Electrical Discharge Machining on the Fatigue Properties of High Strength Stainless Steel This technical report (NLR-TP-2003-104) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2003 and was written by L. Velterop. Conventional Electrical Discharge Machining (EDM) can decrease component fatigue life and strength. On the other hand, wire-EDM might be less detrimental because the energy input is lower and consequently there is a thinner surface layer modified by the process. The influence of wire-EDM on the S-N fatigue properties of a high strength martensitic stainless steel was investigated. First the effect of four sets of wire-EDM parameters on the surface topography and surface layer thickness was determined. Subsequently, one set of parameters was chosen for the fatigue tests, which included reference specimens produced by abrasive jet machining. At stress levels giving fatigue lives less than 106 cycles there was no difference in average lives between the reference and wire-EDM specimens. However, the latter showed a significantly lower fatigue strength. [Taken from abstract]. The full text is available as a PDF file. Inspection Development for Titanium Forgings Thisprovides access to a Federal Aviation Administration (FAA) report DOT/FAA/AR-05/46 by F.J. Maretan ...[et al] dtaed June 2007. The Forging Inspection Development task started in June 1999 with the primary objective of advancing the state of the art in ultrasonic forging inspection sensitivity from #1 flat-bottom hole (FBH) (1/64? diameter) to #1/2 FBH (1/128? diameter), increasing in sensitivity by a factor of four. The improvement was achieved and demonstrated with the use of a phased array inspection system at the Iowa State University phased array test bed. Significant development work was performed to establish the ultrasonic beam parameters that would do the high-sensitivity inspection in forged titanium rotors. Attempts were made at using both fixed-focus, single-element transducers and a phased array approach for the desired focus at various zone depths. After it was determined that the fixed-focus transducers could not be manufactured using existing manufacturing technology at the required diameters and frequency, the team concentrated on the phased array approach using a segmented annular array. Based on the noise characteristics that were observed for the various Ti-6-4 samples, it was determined that a 10-MHz beam with a focused spot diameter of 0.045? and 60% bandwidth would be required to reach the #1/2 sensitivity. The improved sensitivity was demonstrated by inspecting samples of Ti-6-4 forgings with #1/2 FBHs drilled to the depths of the inspection zones and by scanning several forgings with the high-sensitivity setting to determine if the ultrasonic noise caused unacceptable false calls. A relatively complex phased array transducer was designed and fabricated to specifications on the first attempt. Feasibility was demonstrated with this transducer, and demonstrated to the Federal Aviation Administration and industry representatives on a flat specimen. Besides the development required to establish the necessary ultrasonic beam characteristics, other technical aspects were studied during the program. These included a study of surface finish requirements, an evaluation of area amplitude comparison at #1 and #1/2 FBH sizes, a means of correcting for surface geometry using curved mirrors, and a means of evaluating signal-to-noise levels with the forging C-scan data. Additional features would need to be developed to implement in a production environment. [Taken from abstract]. The full text is available in PDF format from the online catalogue of the FAA William J. Hughes Technical Center Library. Intelligent Processing of High Performance Materials This site provides access to a Research and Technology Organisation Meeting Proceedings, RTO-MP-009, Paris, November 1998. The document contains papers presented at a Workshop on Intelligent Processing of High Performance Materials organised by the Applied Vehicle Technology Panel (AVT) of RTO, in Brussels, Belgium, 13-14 May 1998. It describes various aspects of intelligent processing, a methodology for simulating and controlling the processing and manufacture of materials, which is finding widespread application during the manufacture of functional electronic, photonic and composite materials as well as primary metals such as steel and aluminium. The papers are presented under the following headings: •Overview and analytical techniques •Metallic materials applications •Non-metallic materials applications Bibliographic and abstract details are available in HTML format. A table of contents, and the full text of the document (18.5 Mbytes) 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. Low Cost Composite Structures and Cost Effective Application of Titanium Alloys in Military Platforms This site provides access to a Research and Technology Organization Meeting Proceedings, RTO-MP-069 (II), Paris, March 2003. The document contains papers presented at the Symposium of the RTO Applied Vehicle Technology Panel (AVT) Specialists Meeting held in Loen, Norway, 7-11 May 2001. Bibliographic and abstract details are available in HTML format. The meeting provided a forum for information exchange and discussions by specialists on the cost effective application of titanium alloys to air, land and sea platforms. Twenty presentations from nine countries discussed titanium extraction, casting technology, component fabrication, use for ballistic protection, and applications in platform subsystems. A table of contents, and the full text (98.6 Mbytes) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library. 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. Molecular Nanotechnology in Aerospace : 1999 This web page provides online access to a NASA Ames Research Center report, prepared by Al Globus, published January 2000. The report presents a high-level discussion of molecular nanotechnology, and addresses potential aerospace applications including, computers, materials and sensors. A bibliographic description and abstract is available in HTML format. The full text can be accessed online in either HTML format (2 Mbytes) or PDF format (3.4 Mbytes). The document is contained in the Papers and Reports section of the NASA NAS Systems Division's web site. Nanotechnology Aerospace Applications This is a NATO Research and Technology Organization (RTO) Educational Note, RTO-EN-AVT-129, Paris, December 2005. The material in this publication was assembled to support a Lecture Series under the sponsorship of the Applied Vehicle Technology Panel (AVT) presented on 9-10 May 2005 in Monterey, USA; 12-13 May 2005 in Montreal, Canada; 30-31 May 2005 in Ankara, Turkey; and 2-3 June 2005 in Brussels, Belgium. The Educational Notes contain the abstracts and the lecture material of ten presentations, which provide a general introduction into nanotechnologies with selected topics, such as nanotechnology fabrication, characterization, applications (lifestyle, defence, and aerospace), and commercialisation. The lectures show that nanotechnology is an enabling technology that will impact electronics and computing, materials and manufacturing, health, medicine, energy, transportation, and other areas. Bibliographic and abstract details are available in HTML format. A table of contents, individual papers and the full text of the document (54.0 Mbytes) can be accessed online in PDF format. 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. 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). Nondestructive Evaluation of Superalloy Specimens with a Thermal Barrier Coating This technical report (NLR-TP-2004-154) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2004 and was written by J. H. Heida. This paper describes an investigation into the applicability of NDE techniques for the inspection of superalloy specimens with a thermal barrier coating (TBC), both in unloaded condition and during constant load exposure at high temperatures (creep). More specifically, the eddy current (ET) and ultrasonic (UT) techniques were investigated for the characterisation of the TBC (at room temperature), while the acoustic emission (AE) technique was examined for the monitoring of the degradation incurred in the material during creep (at high temperature). Both uncoated and TBC specimens of single crystal and directionally solidified material were used in the investigation. The main conclusions of the investigation are: - The ET technique can be effectively used in the measurement of the coating thickness. The phase and the length of the lift-off response give information about the thickness of the bond coat and top coat, respectively. Differences in the bond and top coat thickness of about 20 μm can be distinguished (in the specific thickness range of interest). - The UT technique does not provide enough information about the thickness or the quality of the TBC. - The AE technique can be effectively used during creep testing to monitor the evolution of the material degradation, particularly in the coating layer of the TBC specimens. A distinctly different AE response was observed in the TBC specimens when creep tested at a different temperature (750 to 950ºC). A correlation between the number of AE events and the number of coating cracks was demonstrated. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it. 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. Optical Investigation of Transition Metal Implanted Wide Band Gap Semiconductors This is the full text of a Master's thesis by First Lieutenant Brian P. Feller, USAF, AFIT/GEO/ENP/05-02, which was presented to the Faculty Graduate School of Engineering and Management of Air University's Air Force Institute of Technology (AFIT), in March 2005. Thin films of GaN, Al(sub 0.1)Ga(sub 0.9)N, and ZnO were implanted with Cr, Mn, and nickel Ni to produce dilute magnetic semiconductors. Optical and magnetic techniques were used to evaluate crystal structure restoration and coercive field strength as a function of implant species and annealing temperature. Maximum crystal restoration was obtained for Al(sub 0.1)Ga(sub 0.9)N after annealing at 675 C; for Cr implanted p-GaN after annealing at 750 C; for Mn or Ni implanted p-GaN after annealing at 675 C; for Cr implanted ZnO after annealing at 700 C; for Mn implanted ZnO after annealing at 675 C; and for Ni implanted ZnO after annealing at 650 C. Maximum coercive field strengths were found for Cr implanted Al(sub 0.1)Ga(sub 0.9)N after annealing at 750 C; for Mn implanted Al(sub 0.1)Ga(sub 0.9)N after annealing at 675 C; for Ni implanted Al(sub 0.1)Ga(sub 0.9)N after annealing at 700 C; for Cr or Mn implanted p-GaN after annealing at 725 C; for Ni implanted p-GaN after annealing at 675 C; for Cr or Ni implanted ZnO after annealing at 725 C; and for Mn implanted ZnO after annealing at 725 C. Optimum annealing conditions for optical and magnetic properties of the implanted wide band gap semiconductors agree with each other very 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). 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. Patch Repair of Cracks in the Upper Longeron of an F-16 Aircraft of the Royal Netherlands Air Force (RNLAF) This technical report (NLR-TP-2002-294) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2002 and was written by W.G.J.'t Hart and J.A.M. Boogers. Cracks were detected in the flange of the upper right longeron 16B1111-21, FS 186.90 - FS 247.89 of an F-16 aircraft of the RNLAF. The National Aerospace Laboratory NLR was asked by the RNLAF to consider the possibility of a bonded patch repair. The repair had to last 400 flight hours, at which point the specific F-16 aircraft would be retired from service. Titanium 6A14V sheet was used for repair of the 2 mm thick 2024-T62 aluminium longeron flange. A symmetric bonded repair could be done with a room temperature curing acrylate based adhesive. The feasibility of the proposed repair geometry was determined by performing spectrum fatigue tests. After repair of the F-16 aircraft, periodic inspections were done to check on debonding and fatigue crack propagation. With the retirement from service of the specific F-16 aircraft the project was successfully completed. [Taken from abstract]. The full text is available as a PDF file. Phosphoric Sulphuric Acid Anodising : An Alternative for Chromic Acid Anodising in Aerospace Applications? This technical report (NLR-TP-2003-210) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2004 and was written by L. Velterop. In spite of regulations aimed at the reduction of the amount of chromium VI in waste streams, chromic acid anodising (CAA) is still widely used in the aerospace industry because a suitable replacement has not yet been found. An alternative should provide good corrosion protection, good adhesive bonding properties and be applicable to all aluminium alloys used in the aerospace industry. Furthermore, the fatigue properties should not be reduced more than by chromic acid anodising. Phosphoric sulphuric acid (PSA) anodising proved to be a possible alternative for CAA for 2XXX series alloys. Its applicability to 7XXX series alloys is discussed in the present paper. The most promising anodising parameters were selected from a large matrix of conditions, based on the microstructure and thickness of the anodic layers obtained on clad 7075-T6. The fatigue properties and corrosion protection capabilities were evaluated for the selected PSA anodising process in comparison to chromic acid anodising. Because the process parameters differed from those of the PSA process established previously for 2XXX series alloys, the selected process was also tested on 2024-T3 and evaluated with respect to microstructure and corrosion protection capabilities. The constant amplitude fatigue behaviour was found to be equal for PSA and CAA treated aluminium. The corrosion protection by PSA anodic layers was not as good as that of CAA anodic layers, which can be explained largely by the differences in thickness of the anodic layers. After application of a chromate-free primer, both anodising processes provided equal protection against corrosion. [Taken from abstract]. The full text is available as a PDF file. 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. 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. Repair Types, Procedures – Part I
This is the full text publication that was assembled to support a Lecture Series under the sponsorship of the Applied Vehicle Technology Panel (AVT) presented on 17-18 May 2010 in Prague, Czech Republic. Repair Types, Procedures – Part II
This is the full text publication that was assembled to support a Lecture Series under the sponsorship of the Applied Vehicle Technology Panel (AVT) presented on 17-18 May 2010 in Prague, Czech Republic. Selected Current Aerospace Notices Provided by NASA, Selected Current Aerospace Notices (SCAN) is a weekly electronic current awareness journal that announces recently issued report and journal literature from the NASA scientific and technical information knowledge base. SCAN covers the full spectrum of aeronautics and aerospace-related information and segments it into subject groupings, or topics, which are narrower in scope than the 76 categories provided by Scientific and Technical Aerospace Reports (STAR). Furthermore, SCAN announces documents simultaneously in all relevant topics. Document citations announced in STAR are presented in only the one subject category deemed most appropriate. Each of the 186 SCAN topics is carefully tailored to fit the needs of a specialized research activity. New topics are added as the need arises, and others are retired or redefined as research demands dictate. The service is also searchable. Significance of Dwell Cracking for IN718 Turbine Discs This technical report (NLT-TP-1999-392) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 1999 and was written by R. J. H. Wanhill. High temperature ?dwell cracking? of the nickel-base superalloy IN718 was investigated as part of a European project on military aircraft turbine discs. Dwell and fatigue crack growths tests under simple loading conditions indicated that dwell cracking would be unlikely to occur under actual flight loadings and that standard fracture mechanics specimens may be inappropriate for predicting crack growth in discs. Flight-by-flight loading tests showed that dwell cracking was either absent or limited. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it. 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. Society of British Aerospace Companies Technical Specification TS95 This SBAC technical specification (Issue 7) is dated 16 July 2005 and presents a listing of recommended/preferred metallic materials specifications to be used for new aircraft designs. It is available in PDF format and forms part of the SBAC's voluntary stanandardisation programme. Please note that to access the full text of the document you must be eligible as a registered user. Society of British Aerospace Companies Technical Specification TS96 This SBAC technical specification (Issue 4) and presents a listing of potential alternative materials specifications for British National materials standards (BS Aerospace and DTD Standards). It is available in PDF format and forms part of the SBAC's voluntary stanandardisation programme. Please note, some content and pages, including this document are for SBAC website members only and require registration and login to access them. An online registration facility is available. Technology Requirements for Small Gas Turbines This is Research and Technology Organization (RTO) AGARD-CP-537, dated March 1994. These Conference Proceedings contain the papers presented at the Propulsion and Energetics Panel 182nd Symposium on Technology Requirements for Small Turbines which was held from 4th-8th October 1993, in Montreal, Canada. The Technical Evaluation Report and the Technology Overview Address are included at the beginning, and discussions follow most papers. The Symposium was arranged in the following Sessions: Technology Overview; Turboshaft Engines; Turbofan Engines; Auxiliary Power Units; Compressors 1 - Centrifugal; Compressors 2 - Axial; Combustors; Turbines 1 - Axial; Turbines 2 - Radial; Structures and Materials; and Bearings. For individual titles, see N94-34432 through N94-34466. Bibliographic and abstract details are available in HTML format. A table of contents, and the full text (31.57 MB) of the document can be accessed online in PDF format. The document is contained in the RTO's Full Text Publication Library. Test and Interpretation of Small Fatigue Crack Growth in Metallic Rotocraft Stuctures with Emphasis on the Statistical Characteristics This provides access to a Federal Aviation Administration (FAA) technical report DOT/FAA/AR-08/6 written by Marcus Cappelli, Robert Calson and George Kardomatea dated February 2008. This report presents the results of an experimental program on the growth of small, multisite fatigue cracks on smooth surfaces in 7075-T7351 aluminum. It was shown that the resulting population of measured cracks was bimodal. That is, it consisted of primary cracks that can grow until failure by fracture in each specimen, and secondary cracks that ultimately arrest. An experimental procedure for separating the two distributions was developed and used to obtain confidence intervals for crack length versus loading cycles. A microstructurally based transition point between small and long crack behavior was also developed and used. Topics for additional research that need to be further developed and applied to the bimodal model of cluster small crack growth are presented. [Taken from abstract]. The full text is available in PDF format so Adobe Acrobat software is required in order to read it. Tests and Interpretation of Small Fatigue Crack Growth in Metallic Rotorcraft Structures With Emphasis on the Statistical Characteristics This technical report (DOT/FAA/AR-08/6) was published by the Federal Aviation Administration (FAA) Office of Aviation Research and Development in February 2008 and was written by Marcus D. Cappelli, Robert L. Carlson and George A. Kardomateas. This report presents the results of an experimental program on the growth of small, multisite fatigue cracks on smooth surfaces in 7075-T7351 aluminum. It was shown that the resulting population of measured cracks was bimodal. That is, it consisted of primary cracks that can grow until failure by fracture in each specimen, and secondary cracks that ultimately arrest. An experimental procedure for separating the two distributions was developed and used to obtain confidence intervals for crack length versus loading cycles. A microstructurally based transition point between small and long crack behavior was also developed and used. Topics for additional research that need to be further developed and applied to the bimodal model of cluster small crack growth are presented. [Taken from abstract]. This is a PDf file, so Adobe Acrobat software will be required in order to read it. 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 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 Effect of a Hard Coating on the Damping and Fatigue Life of Titanium This is the full text of a thesis by Frank T. Ivancic which was presented to the Air Force Institute of Technology (AFIT) in 2003. This project compares the damping and fatigue life of bare titanium plates to those coated with magnesium aluminate spinel (mag spinel). Two different coating thicknesses were tested: .005 per side and .010 per side (total thicknesses of .010 and .020). Dynamic ping tests were conducted on all specimens to determine their resonance frequencies. Laser vibrometry was used to determine the mode at each resonance frequency. Damping ratios were determined through the use of sine sweeps. A vibration mode was selected at which to fatigue the specimens, and the stress pattern was analyzed utilizing the Stress Pattern Analysis by Thermal Emissions (SPATE) process. Once characterization was complete, fatigue testing was conducted on the thick plates utilizing the resonant dwell process. The specimens were vibrated by applying a harmonic excitation through the base. The strain level which would result in fatigue at 106 cycles, and the velocity necessary to achieve this strain were determined. The test specimens were excited at this velocity, and the number of cycles to failure was noted. Results were compared for the uncoated, thin coated, and thick coated specimens. [Take from abstract]. The full text of the thesis is available in PDF format and is provided by the Air University ResearchWeb site. The Effects of Advanced Materials on Airframe Operating and Support Costs This provides access to RAND report DB-398-AF, prepared by Raj Raman, John C. Graser, and Obaid Younossi, dated 2003. The report has been published as part of the Project Air Force programme. The report examine whether airframe parts made of advanced materials, such as polymer composites and titanium, cost more to maintain than parts made of aluminium. A description of the report is available in HTML, while the full text of the document is available for browsing online and downloading in PDF (2.6 MB) format. The Role of Grain Size Inembrittlement of Archaeological Silver This technical report (NLR-TP-2001-125) was published by NLR (the National Aerospace Laboratory of the Netherlands) in 2001 and was written by R. J. H. Wanhill. Archaeological silver may be embrittled by long-term corrosion and microstructural changes. The embrittlement of artifacts increases with increasing grain size. This is explained by considering the grain boundary character and models describing the interactions between microcracks, lattice dislocations and grain boundaries. Severely embrittled artifacts are frangible or even friable. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it. The Temperature Distribution Within Solid Metal Cylinders Subjected to a Standard Aircraft Engine Fire This technical report (DOT/FAA/AR-04/1) was produced by the Aviation Research Office of the Federal Aviation Administration (FAA) in April 2004 and was written by John W. Reinhardt, Dung Do and Jason Fayer. This report provides temperature data that could be used to establish the ultimate tensile strength (UTS) loss of candidate engine mount materials after been exposed to a standard flame for 5 and 15 minutes. The materials tested included 4130 steel (baseline),15-5 PH steel, titanium 6A1-4V, Inconel 718, and aluminum 7075. These materials were instrumented internally with thermocouples and exposed to the standard flame. MIL-Handbook-5H provides some data with regards to the UTS loss of these materials while heated, but additional strength tests must be conducted to account for the higher temperatures experienced by these materials while exposed to the standard fire. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it. 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. Titanium :Industrial Base, Price Trends, and Technology Initiatives This provides access to a Rand Organization publication written by Somi Seong ...[et al] dated 2009. Titanium accounts for a significant portion of the structural weight of many aircraft. Its high strength-to-weight ratio, high strength at high temperatures, corrosion resistance, and thermal stability make it ideal for airframe structures. However, in recent years a combination of multiple factors has caused a major spike in titanium prices that is expected to significantly influence the acquisition costs of future aircraft. This monograph examines the titanium industrial base, titanium production technology, and the factors underlying price fluctuations in the titanium market to assess their implications for the production cost of future airframes. The authors also suggest how the Department of Defense might mitigate the economic risks involved in the titanium market and reduce the cost of raw materials used in military airframes. In contrast with existing studies, which mainly focus on aircraft demand cycles in analyzing titanium price fluctuations, the monograph highlights the role of supply-side drivers, China's impact on the titanium market through cross-market substitution effect, the significance of industrial demand, and the increase in spot market transactions. [Taken from abstract]. The full text is avaialble in PDF format so Adobe Acrobat software is required in order to read it. Turbine Rotor Material Design : Final Report This provides access to a Federal Aviation Administration (FAA) report, DOT/FAA/AR-00/64, by G.R. Leverant and others, dated December 2000. The reports describes the development of a probabilistically based, damage tolerance design code to augment the current safe-life approach for life management of commercial aircraft gas turbine rotors/disks. The design code is intended to provide an additional tool that engine manufacturers can use for reliability assessment. Initial application of the code focused on melt-related anomalies (hard alpha (HA)) in titanium. Supplemental tests were also performed to determine the mechanical properties of hard alpha and titanium disk alloys, and a forging code was developed to predict the shape and orientation of hard alpha anomalies during processing. The full text of the report is available in PDF format, from the online catalogue of the FAA William J. Hughes Technical Center Library. Turbine Rotor Material Design : Phase II This provides access to a Federal Aviation Administration (FAA) technical report written by R. C. McClung ...[et al] and dated April 2008. The Federal Aviation Administration (FAA) is working with the aircraft engine industry to develop an enhanced life management process, based on probabilistic damage tolerance principles, to address the threat of material or manufacturing anomalies in high-energy rotating components, and the process is documented in current and planned versions of FAA Advisory Circular (AC) 33.14. An integrated team of Southwest Research Institute, GE Aviation, Pratt & Whitney, Honeywell, and Rolls-Royce Corporation has developed enhanced predictive tool capability and supplementary material/anomaly behavior characterization and modeling to support and enhance the process and the AC. Sensitivity studies were performed to guide a planned update of the hard alpha (HA) anomaly distributions. A computer code was developed to describe the diffusion of nitrogen or oxygen in titanium (Ti) from an inclusion during melting and heat treatment. The DEFORM™ forging microcode was validated experimentally and used to study cracking of HA anomalies during forging. Ultrasonic inspection methods were evaluated at the billet and forging stages. The influence of elevated oxygen on Ti-17 was evaluated with tensile and fatigue tests. Spin pit and coupon experiments were conducted to study the fatigue behavior of embedded HA. Vacuum fatigue crack growth (FCG) data were generated for three nickel alloys and Ti-6242. Thermomechanical FCG behavior was studied in IN-718. A literature survey was conducted on the stability and significance of surface residual stresses in fatigue. New DARWIN® versions were developed to address anomalies associated with surface damage in three-dimensional (3D) components and different types of inherent anomalies (including large numbers of 3D anomalies and nonnegligible crack formation lives). Enhancements in the probabilistic methods and many other new capabilities were developed to improve the overall efficiency and accuracy of the risk assessment computations in DARWIN. The partnered engine companies verified the accuracy and usability of DARWIN. A three-day DARWIN training workshop was conducted. An infrastructure was developed to support code licensing and distribution for users employing DARWIN. [Taken from abstract]. The full text is availabale in PDF format so Adobe Acrobat software is required in order to read it. Update of Default Probability of Detection Curves for the Ultrasonic Detection of Hard Alpha Inclusions in Titanium Alloy Billets This technical report (DOT/FAA/AR-07/63) was published by the Federal Aviation Administration (FAA) Office of Aviation Research and Development in February 2008 and was written by R. Bruce Thompson, Bill Meeker, Mike Keller, Jeff Umbach, Thomas Chiou, Yurong Wang, Dick Burkel, Waled Hassan, Kevin Smith, Thadd Patton and Lisa Brasche. This report describes efforts to update the default probability of detection (PoD) curves for the ultrasonic detection of hard alpha inclusions in titanium alloy billets, with the results intended to replace the curves currently found in Advisory Circular 33.14-1, "Damage Tolerance for High Energy Turbine Engine Rotors." This report describes the data on which the update is based, the statistical approaches used to analyze those data, the results of the PoD analysis, technical issues encountered during the analysis, and conclusions. The original Default PoD curves were based on what is known as the Default PoD-3Dimensional database, which documents the results of inspections conducted before 1995 using conventional inspection techniques. Two additional sets of data that became available after 1995 are described in this report and greatly extend the information available. The updated PoD curves are found to be considerably different from the previous curves, obtained in 1995, with the PoD of the Multizone technique shown to be clearly superior to that of the conventional inspection technique. [Taken from abstract]. This is a PDF file, so Adobe Acrobat software will be required in order to read it. Wear Analysis of CU-AL Coating on TI-6AL-4V Under Fretting This is the full text of a Master's thesis by Ensign Karl N. Murray, USN, AFIT/GAE/ENY/06-J12, which was presented to the Faculty Department of Aeronautic and Astronautics of Air University's Air Force Institute of Technology (AFIT), in June 2006. The effects of changes in the coefficient of friction (CoF) between the contacting surfaces on the fretting wear characteristics of Cu-Al coating on Ti-6Al-4V were investigated. This Cu-Al coating is part of a system that is applied to titanium turbine blades to reduce fretting at the interface. In the application, there is a solid lubricant that is added on top of the coating as an assembly aid and to help reduce the friction while the lubricant remains within the contact. Previous studies have researched the characteristics of the coating without the additional lubricant. In this study, liquid motor oil was applied to the contact region to simulate real-world conditions with a lower CoF. To characterize the wear, several methods were used, the most useful being the accumulated dissipated energy method. The accumulated relative displacement method did not take into account the differences between the tangential forces for tests conducted at different CoF values, whereas the dissipated energy method did. The wear characteristics of tests conducted in the current study were similar to those of a previous study, conducted at a higher CoF, when analyzed with the dissipated energy method, but this was most likely due to the ambiguity of the calculated wear volumes. [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). 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. |
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