| A Computational Comparison of High Strain Rate Strength and Failure Models for Glass |
05 Nov 2012 |
11 pages |
| Authors:
Timothy G Talladay; Douglas W Templeton; ARMY TANK AUTOMOTIVE RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
|
 | Computational studies are performed using the recent Holmquist-Johnson glass model and the earlier Johnson-Holmquist brittle material model. Although the JH-2 model has been adapted to provide reasonably accurate predictions for soda-lime glass, the Holmquist-Johnson model was developed specifically to replicate the behaviors of glass. Simulations of rod impact on borosilicate glass using these two models are compared to experiments involving impact of mild steel rods and borosilicate glass at ca. ... |
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| Microwave Power Transmission Using Electromagnetic Coupling of Open-Ring Resonators |
01 Nov 2012 |
24 pages |
| Authors:
Yasuo Ohno; TOKUSHIMA UNIV (JAPAN)
|
| Experimental results on 60GHz band signal transmission through ECOR (Electromagnetic Coupling of Open-Ring Resonators) are shown. Through sapphire substrate, 60-70GHz band signal are transmitted with 58.9% transmission efficiency and 7.4GHz bandwidth. However, the transmission band was shifted about 10GHz higher frequency. The reason is under investigation. ECOR technology is extended to lower frequencies for non-contact power transmission. The technology will benefit to power connectors for equipment modules where the problems ... |
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| Kunduz ANA Garrison: Army Corps of Engineers Released DynCorp of All Contractual Obligations despite Poor Performance and Structural Failures |
Oct 2012 |
34 pages |
| Authors:
SPECIAL INSPECTOR GENERAL FOR AFGHANISTAN RECONSTRUCTION ARLINGTON VA
|
| What SIGAR Reviewed: The Combined Security Transition Command-Afghanistan, through the Afghanistan Security Forces Fund, provided $72.8 million to the U.S. Army Corps of Engineers (USACE), Afghanistan Engineer District-North (TAN) to construct an Afghan National Army garrison (Camp Pamir) in Kunduz province. USACE-TAN awarded two construction contracts to DynCorp International LLC (DynCorp). As part of its inspection program, the Special Inspector General for Afghanistan Reconstruction (SIGAR) followed up on actions USACE-TAN ... |
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| Effective Measurement of Reliability of Repairable USAF Systems |
Sep 2012 |
81 pages |
| Authors:
Louis J Hogge; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The USAF generally does not know the reliability of its fielded repairable systems. The reported metric, Mean Time Between Failure (MTBF), is too lagging to be actionable in the best case, and is not representative of actual system reliability in the worst case. This thesis investigates the statistical techniques for measurement and analysis of the reliability of fielded repairable systems, which are very different than nonrepairables. To frame the investigation, ... |
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| Powertrain Embedded Diagnostic and Predictive Capability for an Automotive Transmission |
Aug 2012 |
13 pages |
| Authors:
Jim Bechtel; Larry Marino; Mitchell Lebold; Scott Pflumm; Jeffrey Banks; Jason Hines; Jonathan Bednar; PENNSYLVANIA STATE UNIV STATE COLLEGE APPLIED RESEARCH LAB
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| This report documents the investigation of a vibration-based diagnostic approach developed for automotive transmissions. Data was recorded throughout three durability tests that were conducted by the transmission OEM. Rebuilt transmissions were operated around the clock under the most demanding speed and load set-points until critical gear or bearing failures resulted in loss of operability. The analysis results indicate that an embedded diagnostic and predictive capability can be implemented for military ... |
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| A Comprehensive Structural Analysis Process for Failure Assessment in Aircraft Lap-Joint Mimics Using Multi-Modal Fusion of NDE Data (Preprint) |
Jul 2012 |
36 pages |
| Authors:
Soumya De; R J Stanley; Mohammad T Ghasr; Reza Zoughi; Kenneth Doering; David Van Aken; Matt O'Keefe; Kapil Gupta; Donald Palmer; Gary Steffes; MISSOURI UNIV OF SCIENCE AND TECHNOLOGY ROLLA
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| Multi-modal data fusion techniques are commonly used to enhance decision-making processes. In previous research, a comprehensive structural analysis process was developed for quantizing and evaluating characteristics of defects in aircraft lap-joint mimics using eddy current nondestructive evaluation (NDE) data collected for structural health monitoring. In this research, a comprehensive multi-modal structural analysis process is presented that includes intra- and inter-modal NDE data fusion. The process includes defect detection, defect characterization ... |
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| Brick Paving Systems in Expeditionary Environments: Field Testing |
Jul 2012 |
101 pages |
| Authors:
Haley P Bell; Quint Mason; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| Personnel of the U.S. Army Engineer Research and Development Center were tasked by Headquarters, Air Force Civil Engineer Support Agency, to determine the feasibility of using face bricks as an alternative to concrete or asphalt paving for low-volume roads and military aircraft parking aprons in expeditionary environments. Because paving materials and equipment can be scarce in these areas, the use of recycled bricks from existing infrastructure might provide a local ... |
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| Microstructurally Engineered Armor System for Enhanced Survivability through Optimum Energy and Momentum Dissipation |
18 Jun 2012 |
61 pages |
| Authors:
M A Zikry; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| This project is focused on the optimization and development of a new class of high strength and lightweight aluminum alloys for armored systems subjected to high rate and severe loading conditions associated with IED events. The current effort is led by North Carolina State University (M.A. Zikry, D. Brenner, NCSU) An integrated experimental and atomistic and microstructural modeling framework has been developed and used to rapidly identify dominant microstructural characteristics ... |
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| Microstructurally Engineered Armor System for Enhanced Survivability through Optimum Energy and Momentum Dissipation |
02 Jun 2012 |
55 pages |
| Authors:
M A Zikry; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| This project is focused on the optimization and development of a new class of high strength and lightweight aluminum alloys for armored systems subjected to high rate and severe loading conditions associated with IED events. The current effort is led by North Carolina State University (M.A. Zikry, D. Brenner, NCSU) An integrated experimental and atomistic and microstructural modeling framework has been developed and used to rapidly identify dominant microstructural characteristics ... |
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| Practical Application of Residual Stress Measurements on Maritime Vessels |
Jun 2012 |
99 pages |
| Authors:
Dixon T Whitley; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| This thesis examines the practical application of portable X-ray diffraction to measure residual stresses on board active maritime platforms. These measurements will provide better understanding of structural failures in aluminum hulls and superstructures. The feasibility of this process was analyzed by comparing data from welded aluminum test samples using portable X-ray diffractometers from three different sources. The effects on residual stress from ultrasonic impact treatments were measured using laboratory X-ray ... |
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| Damage Study in an AA 2024 T3 Panel Subjected to Explosive Loading |
May 2012 |
14 pages |
| Authors:
T Sano; C Fountzoulas; C F Yen; C Chen; M Nansteel; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Aluminum alloys are the prime metallic materials used for light weight industrial applications. Experimental characterization of the damage in AA 2024 T3 alloy subjected to close-in blast loading is one of the critical steps to assess and improve the safety of the passenger and cargo transportation systems. Currently, several aluminum alloys are also considered by the DoD for applications such as armor for vehicles and other protection systems. AA 2024 ... |
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| Missile Defense: Opportunities Exist to Strengthen Acquisitions by Reducing Concurrency and Improving Parts Quality |
25 Apr 2012 |
21 pages |
| Authors:
GOVERNMENT ACCOUNTABILITY OFFICE WASHINGTON DC
|
| In fiscal year 2011, the Missile Defense Agency (MDA) experienced mixed results in executing its fiscal year 2011 development goals and tests. For the first time in 5 years, GAO was able to report that the agency delivered all of the targets used in fiscal year 2011 test events with the targets performing as expected. In addition, the Aegis Ballistic Missile Defense program s Standard Missile-3 Block IA missile was ... |
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| Energy Absorption Mechanisms in Unidirectional Composites Subjected to Dynamic Loading Events |
30 Mar 2012 |
36 pages |
| Authors:
David B Segala; Paul V Cavallaro; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI RANGES ENGINEERING AND ANALYSIS DEPT
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| This report documents the numerical modeling that was conducted to study the failure modes in dynamically loaded, unidirectional (UD) fibrous composites. The purpose of this research was to determine how to increase energy absorption capacities during severe dynamic loading events. Energy absorption mechanisms are generally composed of elastic, inelastic, kinetic, frictional, acoustic, thermal, and dissipative sources. In this study, the inelastic energy absorption mechanisms associated with damage at the interfacial ... |
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| Electromagnetic Interference Behavior of Multiwall Carbon Nanotubes and Carbon Nanofibers Composites Under Fatigue |
Mar 2012 |
151 pages |
| Authors:
Peter A Hunt; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The United States military is researching the use of nanocomposite materials for structural applications on space vehicle systems. To reduce vehicle weight and mitigate the electromagnetic interference (EMI) brought on by the harsh space environment, today's space vehicles are made of composites coated with expensive conductive materials. Research on composites made of carbon nanotubes (CNT) and carbon nanofibers (CNF) has shown better EMI shielding performance with these materials compared to ... |
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| Mechanical Behaviour of Bolted Joints Under Impact Rates of Loading |
Jan 2012 |
85 pages |
| Authors:
Andrew VanderKlok; MICHIGAN STATE UNIV EAST LANSING
|
| Bolted joints are extensively used in many automotive and aeronautical sectors where two members are bolted together. This particular method of fastening is vastly used in many industrial disciplines as it serves as an easy and non-destructive method to join and subsequently disassemble a complex structure. Since, bolted joints constitute an integral part of many structural components, this directly implicates the necessity to investigate the mechanical response of the bolted ... |
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| Flame Structure of Vitiated Fuel-Rich Inverse Diffusion Flames in a Cross-Flow (Postprint) |
Dec 2011 |
12 pages |
| Authors:
David Blunck; Amy Lynch; Joseph Zelina; James R Gord; Stanislav Kostka; Sukesh Roy; Marc Polanka; Scott Stouffer; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Fuel-rich streaks or dissociated combustion products exiting from gas turbine combustors may react with jets of turbine vane cooling air. These fuel-rich vitiated inverse diffusion flames can potentially cause structural failure of turbine vanes due to the excessive heat fluxes. In this study OH planar laser induced fluorescence measurements are conducted in fuel-rich vitiated flows advecting over a flat plate with a row of cooling holes normal to the surface. ... |
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| Study of the Progressive Failure of Composites under Axial Loading with Varying Strain Rates |
Dec 2011 |
79 pages |
| Authors:
Yew K Boey; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This study investigated the progressive damage/failure of composite panels with open circular holes under progressive axial loading. A series of experiments was carried out to determine the failure in laminated specimens with and without circular holes under tensile and compressive loads, respectively. Different strain rate loading was applied to observe the rate effect on the damage initiation and propagation. Both uniform and non-uniform strain rate loads were applied to the ... |
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| Model-Based Structural Health Monitoring of Fatigue Damage Test-Bed Specimens |
15 Nov 2011 |
26 pages |
| Authors:
Kincho H Law; Jerome P Lynch; Masahiro Kurata; MICHIGAN UNIV ANN ARBOR DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
|
| This research project represents a preliminary investigation into a comprehensive analytical, numerical, and experimental framework for the monitoring and life-cycle assessment of the structural integrity and performance of aluminum hull structures. Aluminum plate specimens were designed and fabricated to facilitate the investigation of system identification and damage detection methodologies, both of which are key components of future life-cycle analyses. The design of the plate specimens was intended to include the ... |
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| A Framework for Probabilistic Assessment of Fracture Mechanics Life (Preprint) |
Nov 2011 |
19 pages |
| Authors:
Srikanth Akkaram; Adrian Loghin; Genghis Khan; GE GLOBAL RESEARCH CENTER NISKAYUNA NY
|
| This report was developed under a SBIR contract for topic AF103-157. The paper develops a framework for application of probabilistic methods to assess the variability in fracture mechanics life for components. The probability of failure for a component at a specific failure location is typically defined by a crack size exceeding a threshold crack size (e.g. as defined by repair or bore-scope inspection limits). The computation of the probability of ... |
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| Investigation of Failed Components from a 7-in High Altitude Research Program (HARP) Cannon |
Nov 2011 |
52 pages |
| Authors:
Scott M Grendahl; Matthew Motyka; Sean Fudger; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The U.S. Army Research Laboratory (ARL) experienced a failure during a test firing of a 7-in High Altitude Research Program (HARP) cannon at EF-9 on 13 October 2010. Subsequently, a team was formed and an investigation into the mishap was conducted. The Lightweight and Specialty Metals Branch (LSMB) within the Materials and Manufacturing Sciences Division (MMSD) was tasked with conducting a failure investigation of two components determined to have catastrophically ... |
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| An Assessment of Peridynamics for Pre and Post Failure Deformation |
Nov 2011 |
45 pages |
| Authors:
Richard Becker; Richard J Lucas; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The peridynamics method was examined in the context of deformation conditions commonly observed before and after dynamic material failure by using a combination of full simulations, targeted numerical techniques, and analytic solutions. The results show numerical dispersion and boundary condition artifacts expected with nonlocal methods, anomalous volume-shear coupling related to the numerical grid, and limitations of the current material model implementations for large strain and impact simulations. Implications of these ... |
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| Corrosion and Maintenance Data Sharing (Partage des Donnees de Corrosion et de Maintenance) |
Nov 2011 |
88 pages |
| Authors:
NATO RESEARCH AND TECHNOLOGY ORGANIZATION NEUILLY-SUR-SEINE (FRANCE)
|
| The increasing average age of military platforms and greater legislative restriction of maintenance materials that has occurred in the past decade has heavily exacerbated the detrimental effects of corrosion on worthiness and maintenance costs. In order to identify the efficacy of different anticorrosion policies and procedures adopted among the NATO countries, a number of Nations - namely Canada, Germany, Italy, Netherlands, the United Kingdom and the United States - have ... |
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| A Sustainable Approach for Optimal Steel Sheet Pile Structure Assessment, Maintenance, and Rehabilitation |
30 Sep 2011 |
108 pages |
| Authors:
Kevin L Rens; Rui Liu; Stuart Foltz; ENGINEER RESEARCH AND DEVELOPMENT CENTER CHAMPAIGN IL CONSTRUCTION ENGINEERING RESEARCH LAB
|
| The U.S. Army Corps of Engineers (USACE) has constructed a wide variety of civil works structures. Due to age and other factors, many of these structures have deteriorated to a point that they need varying levels of maintenance and repair (M&R). Steel sheet pile (SSP) structures are part of the USACE civilian projects such as lock and dam and other navigation facilities. Failure of a SSP wall or cell can ... |
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| Using Reputation Based Trust to Overcome Malfunctions and Malicious Failures in Electric Power Protection Systems |
SEP 2011 |
268 pages |
| Authors:
Jose E. Fadul; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This dissertation advocates the use of reputation-based trust in conjunction with a trust management framework based on network flow techniques to form a trust management toolkit (TMT) for the defense of future Smart Grid enabled electric power grid from both malicious and non-malicious malfunctions. Increases in energy demand have prompted the implementation of Smart Grid technologies within the power grid. Smart Grid technologies enable Internet based communication capabilities within the ... |
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| Numerical Analysis of Solids at Failure |
20 Aug 2011 |
26 pages |
| Authors:
Francisco Armero; CALIFORNIA UNIV BERKELEY DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING
|
| This report presents a summary of the research supported by the AFOSR during the period June 1 2008 to May 31 2011 on the formulation and analysis of numerical methods for the analysis of failure in solids and structures of interest to the Air Force mission. Of special interest is the consideration of dynamic range, including dynamic fracture and failure. The development of new enhanced finite element methods that incorporate ... |
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| Damage Development in Confined Borosilicate and Soda-Lime Glasses |
11 Jul 2011 |
35 pages |
| Authors:
Kathryn A Dannemann; Jr Anderson Charles E; Sidney Chocron; James F Spencer; SOUTHWEST RESEARCH INST SAN ANTONIO TX
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| Post-test microscopy evaluations were performed on borosilicate (Borofloat (registered trademark) 33) and soda-lime (Starphire (registered trademark)) glass specimens following confined compression tests. These included optical and electron microscopy investigations of select specimens tested at low strain rates with confinement pressures up to 1 GPa. Specimens were evaluated following removal of the confinement sleeve or holder. The objective of this work was to investigate the flow and failure behavior of both ... |
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| Numerical Analysis Study of the Failure Mechanism of Transparent Materials During Low Velocity Impact Used in Protective Systems |
Jul 2011 |
12 pages |
| Authors:
C G Fountzoulas; R E Brennan; J M Sands; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The rapid advancement of computing power and recent advances in numerical techniques and material models have resulted in accurate simulation of ballistic impacts into multi-layer transparent armor configurations. Transparent and opaque materials are used in protective systems for enhancing survivability of ground vehicles, air vehicles, and personnel. Transparent materials are utilized for face shields, riot gear, and vehicle windows, in addition to other applications for sensor protection, including radomes and ... |
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| Modeling of Failure Mechanisms in Composites With Z-Pins-Damage Validation of Z-Pin Reinforced Co-Cured Composite Laminates |
01 Apr 2011 |
25 pages |
| Authors:
Jaime Aguilar; Mauricio Barrera; Guillermo Jaramillo; CENTRO DE INVESTIGACION EN TECHNOLOGIA AERONAUTICA (CITA) CALI (COLUMBIA)
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| The Epoxy Lamina (EL) concept is introduced to explain overall stiffness reduction in Z-pin reinforced composite laminates, as reported by Zhang et al., for a typical 2%-vol fibre content. The concept is applied to a quasi-isotropic laminate, whereby both the softening and strengthening effects are separated out and quantified, based upon experimental data. This study is accompanied by a FEM-based micromechanical addressing of the composite. A set of fibre arrangements ... |
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| Evaluation of the Exceedance Rate of a Stationary Stochastic Process by Statistical Extrapolation Using the Envelope Peaks over Threshold (EPOT) Method |
APR 2011 |
234 pages |
| Authors:
Vadim Belenky; Bradley L. Campbell; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD HYDROMECHANICS DIRECTORATE
|
| The statistical analysis of dynamic stability failures of ships is made extremely difficult due to the problem of rarity. Few or no events of interest may be observed in the amount of time that is feasible for model testing or even simulation. These events, however, may have a finite and non-trivial possibility. The Envelope Peaks Over the Threshold (EPOT) method is a statistical extrapolation technique that was developed to address ... |
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| On Going Projects Related to the PhD in Mechanical Engineering-Engineering Mechanics Program |
21 MAR 2011 |
18 pages |
| Authors:
Sebastian Karwaczynski; ARMY TANK AUTOMOTIVE RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
|
| The U.S Army is always interested in new approaches to self life, manufacturability, weight and performance for Run Flats. Run Flats play a pivotal role in mobility to the Soldier in the event of partial or complete loss of tire air pressure. |
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| A Weakest-Link Approach for Fatigue Limit of 30CrNiMo8 Steels (Preprint) |
MAR 2011 |
30 pages |
| Authors:
S. Ekwaro-Osire; H. V. Kulkarni; TEXAS TECH UNIV LUBBOCK DEPT OF MECHANICAL ENGINEERING
|
| The transfer of fatigue data from laboratory specimens to field components under multiaxial fatigue is a difficult task. This is particularly the case in the transfer of data from specimens with well-defined shapes to components in the field with arbitrary shapes. A number of effects are to be considered in the transfer of data from a laboratory specimen to a field component. These effects include: pure size effect, pure gradient ... |
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| Microstructural Modeling and Representation of Simultaneous Failure Modes in Crystalline Aggregates Subjected to Dynamic Loading Conditions |
09 JAN 2011 |
33 pages |
| Authors:
M. A. Zikry; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| This provides an integrated framework to simultaneously handle different interrelated physical mechanisms, such as a myriad of representative dislocation-density interactions with high and low angle GB interfaces, the growth and coalescence of a population of voids, and how these interactions can lead to either intergranular or transgranular failure. The formation of pile-ups at GB interfaces, as a function of dislocation-density partial and total blockage and absorption at GB interfaces, will ... |
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| Rate-Dependent Homogenization Based Continuum Plasticity Damage Model for Dendritic Cast Aluminum Alloys |
Jan 2011 |
65 pages |
| Authors:
Piyush P Dondeti; OHIO STATE UNIV COLUMBUS
|
| The objective of this dissertation is to develop a computationally efficient rate-dependent homogenization based continuum plasticity damage model for macroscopic analysis of ductile failure in porous ductile materials containing brittle inclusions. The macroscopic model developed in this dissertation is an extension of the model proposed by Ghosh et al. [S. Ghosh, J. Bai, and D. Paquet. Homogenization-based continuum plasticity damage model for ductile failure of materials containing heterogeneities. J Mech ... |
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| Dugway Proving Ground, Utah-American Recovery and Reinvestment Act Project to Repair Power Plant and Replace Failed Generators |
20 DEC 2010 |
9 pages |
| Authors:
INSPECTOR GENERAL DEPT OF DEFENSE ARLINGTON VA
|
| The DoD Office of Inspector General is performing audits of DoD's implementation of Public Law 111-5, "American Recovery and Reinvestment Act of 2009," February 17,2009 (Recovery Act). We selected Recovery Act Project No. 76940 at Dugway Proving Ground (DPG), Utah, to repair the existing electric generation power plant and to replace failed generators (building 4224), which will function as a standby system to provide electricity in the event of a ... |
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| Workshop on Monitoring and Failure Detection in Earthen Embankments |
15 JUN 2010 |
34 pages |
| Authors:
James M. Sabatier; MISSISSIPPI UNIV UNIVERSITY NATIONAL CENTER FOR PHYSICAL ACOUSTICS
|
| Earthen embankments include levees and dams provide water supplies, protect from flooding events, and provide significant environmental services. These embankments are of concern to agencies responsible for their construction, maintenance, inspection, and failure mitigation. Many of the techniques to assess and monitor dams and levees require substantial preparation and effort. Due to the extent of the embankment system and the high cost of failure, rapid, low-cost, highly-reliable inspection and monitoring ... |
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| Penetration Physics of Armor Glass |
30 Nov 2009 |
44 pages |
| Authors:
Donald A Shockey; Donald R Curran; Jeffrey W Simons; Dirk Bergmannshoff; SOUTHWEST RESEARCH INST SAN ANTONIO TX
|
| As part of a team working to develop improved ceramic and glass armor, SRI International performed and interpreted experiments designed to elucidate the physics of material failure when attacked by a rod-like projectile. Partially penetrated glass targets were sectioned and examined to observe the fracture damage. Finely comminuted material in advance of arrested penetrators suggested that frictional properties of fragments influence penetration. A test was devised and applied to measure ... |
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| Prosthetics and Orthotics Manufacturing Initiative (POMI) Phase Zero Final Report: Recommendations on Composite Socket Fabrication Based upon Experimental Results |
20 Jun 2009 |
93 pages |
| Authors:
Christopher W Norfolk; Jon Osborn; SOUTH CAROLINA RESEARCH AUTHORITY (SCRA) ANDERSON SC
|
| The objective of was to gather quantitative data on the materials commonly used to manufacture definitive composite sockets. The purpose was to make informed recommendations to guide socket fabrication. Materials were fabricated into both flat panels and sockets. Flat panels were tested according to ASTM test protocols. Sockets were tested according to the static testing described by the ISO standard for lower limb prostheses. |
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| Tensile Failure Prediction and Measurement in Composite Scarf Repair (Preprint) |
MAY 2007 |
10 pages |
| Authors:
Endel V. Iarve; Timothy D. Breitzman; Benjamin M. Cook; Gregory A. Schoeppner; David H. Mollenhauer; DAYTON UNIV OH RESEARCH INST
|
| Oversized quasi-isotropic tensile specimens were manufactured from IM6/3501-6 graphite/epoxy prepreg. Seven specimens were scarfed in the center of the panel, and four of the panels were subsequently repaired. The repair patch consisted of a ply-by-ply replacement of the removed material with a FM-300M095 film adhesive placed between the repair patch and the scarfed specimen. The patch and adhesive were then co-cured. The repaired and unrepaired specimens were strain gaged and ... |
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| Progressive Failure Analysis of Thin Walled Composite Tubes Under Low Energy Impact |
2007 |
10 pages |
| Authors:
Chian-Fong Yen; Thomas Cassin; Joel Patterson; Matt Triplett; MATERIALS SCIENCES CORP FORT WASHINGTON PA
|
| Composite failure criteria have been developed for dynamic analysis of composite structures. The proposed progressive failure criteria have been integrated into an explicit dynamic analysis code for failure prediction of thin composite tubes subjected to drop weight impact tests. The results provide good correlation with experimental data for impact force histories and some critical damage modes. |
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| Evaluation of Factors Contributing to Damping of Coated and Uncoated Titanium Plates |
23 MAR 2006 |
260 pages |
| Authors:
Dustin W. Lee; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| 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 ... |
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| Robust Multivariate Evaluation and Failure Prediction of Inhomogeneous Solids Based on Inverse Analysis |
31 DEC 2005 |
13 pages |
| Authors:
Toshio Nakamura; STATE UNIV OF NEW YORK AT STONY BROOK
|
| During last three years, successful developments and implementations of inverse analyses techniques for advanced materials have been carried out. Furthermore, novel computational approaches were developed to ascertain failure characteristics of inhomogeneous structural systems. These outcomes are described in the published and submitted journal papers. For the identification and evaluations, experimental procedures were developed for nano-, micro-indentations of elastic-plastic graded materials and anisotropic materials. For composites, two separate techniques were developed ... |
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| A Comparison of the Deformation, Flow, and Failure of Two Tungsten Heavy Alloys in Ballistic Impacts |
DEC 2005 |
11 pages |
| Authors:
Brian Schuster; Lee Magness; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Ballistic tests were conducted with subscale long rod penetrators of two different processing conditions of the same tungsten heavy alloy. The liquid-phase sintered composite of 90% tungsten-9% nickel-01% cobalt (by weight) was tested in its low-strength, as -sintered and heat-treated condition, and in a high-strength, 50% cold-worked (by swaging) and aged condition. Consistent differences in the ballistic performance of the two lots of penetrators were observed, in depth of penetrations ... |
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| Failure of Ductile Materials and Components at High Rates of Loading |
16 SEP 2005 |
9 pages |
| Authors:
L. B. Freund; BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING
|
| The report summarizes progress in understanding plastic strain localization leading to fracture and fragmentation as it occurs in ductile structural components, primarily metals, and on the role of elastomer coatings in suppressing plastic strain localization. The main finding is that the elastomer becomes effective when the bifurcation strain of the ductile metal at which necks begin here's this or to form is roughly comparable to the strain at which the ... |
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| Laboratory Characterization of Fine Aggregate Cementitious Material |
JUL 2005 |
101 pages |
| Authors:
Erin M. Williams; Stephen A. Akers; Paul A. Reed; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| Personnel of the Geotechnical and Structures Laboratory, U.S. Army Engineer Research and Development Center, conducted a laboratory investigation to characterize the strength and constitutive property behavior of a fine aggregate cemented material (FACM). The FACM was designed to have a 34-MPa (5, 000-psi) unconfined strength and to contain no coarse aggregate. Forty-three mechanical property tests two hydrostatic compression tests (HC), four unconfined compression tests (UC), 16 triaxial compression tests (TXC), ... |
|
| Composite Flywheel Development for Energy Storage |
JAN 2005 |
26 pages |
| Authors:
Jerome Tzeng; Ryan Emerson; Paul Moy; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Composite flywheels for energy storage have been proposed and investigated for the past several decades. Successful applications are, however, limited due to the inability to predict the performance, especially the long- term durability. In this investigation, a comprehensive study was proposed with the intent to implement composites in high-performance flywheels. The potential failure mechanism of flywheels constructed with fiber composites was evaluated. Analytical codes for predicting elastic and viscoelastic (long-term) ... |
|
| Recent Biaxial Test Results of Laminated Composites and Analytical MCT Predictions |
18 NOV 2004 |
16 pages |
| Authors:
Jeffry S. Welsh; J. S. Mayes; ALFRED UNIV NY
|
| As the use of advanced composite materials continues to expand into new technology areas, a troublesome issue arises involving the inability of mainstream designers to accurately predict the initiation and growth of the material damage under multiaxial stress states. This shortcoming was clearly illustrated in impressive fashion under the recent "World Wide Failure Exercise". The inability to predict the load response of composite materials in the region of their ultimate ... |
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| Nonlinear Characterizing of the Crack Growth Behavior in a Filled Elastomer |
2004 |
9 pages |
| Authors:
C. T. Liu; M. Yen; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| In this study, the crack growth behavior in a filled elastomer containing hard particles embedded in a rubbery matrix was investigated. The specimen was tested at a constant strain rate of 0.067 cm/cm/min at room temperature. Two initial crack lengths, 2.54 mm and 12.7 mm, were considered. A hybrid experimental-numerical method was used to calculate the J-integral value. The results show that the initial crack length had a significant effect ... |
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| Design and Testing of the Minotaur Advanced Grid-Stiffened Fairing |
2004 |
11 pages |
| Authors:
John Higgins; Peter Wegner; Adrian Viisoreanu; Greg Sanford; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
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| A composite grid-stiffened structure concept was selected for the payload fairing of the Minotaur launch vehicle. Compared to sandwich structures, this concept has an advantage of smaller manufacturing costs and lighter weight. To reduce weight the skin pockets are allowed to buckle visibly up to about 0.5 cm peak displacement. Various failure modes were examined for the composite grid-stiffened structure. The controlling criterion for this design was a joint failure ... |
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| Reexamination of the Requirements to Detect the Failure Wave Velocity in SiC Using Penetration Experiments |
2004 |
6 pages |
| Authors:
Jr. Anderson C. E.; D. L. Orphal; D. W. Templeton; SOUTHWEST RESEARCH INST SAN ANTONIO TX
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| Data for projectile penetration of silicon carbide (SiC) from two types of experiments were combined and analyzed in previous work [1-2]. Analysis of the data suggested the presence of the so-called "failure wave" phenomenon, that is, the apparent increase in the strength of SiC when the penetration velocity exceeds some critical value. These data are used as the basis for the design of a new set of experiments. The objectives ... |
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| Stress Waves and Cohesive Failure in a Finite Strip Subjected to Transient Loading |
MAY 2003 |
7 pages |
| Authors:
George A. Gazonas; David H. Allen; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| New solutions are obtained herein for the dynamic mechanical response of a one-dimensional finite elastic strip that is cohesively bonded to a rigid substrate. Analytic solutions are obtained for a variety of cohesive zone constitutive behaviors including linear elastic, viscous, viscoelastic, and cohesive zones with evolving internal damage. Results are compared to numerically obtained predictions using the explicit finite element code DYNA3D 1. It is shown that the analytic and ... |
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Reports by Keyword(s)
FAILURE(MECHANICS)
