Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 99 for “"Material Response"”.
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Three-dimensional finite-element analysis including elastic-plastic material response
… program is capable of modelling elastic-plastic material behavior. It is based on the constant stiffness iteration employing the initial stress concept. The iterative procedure is accelerated by a new scheme termed uniform acceleration. Three practical applications are presented. The thick-walled …
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An experimental investigation of the material response of graphite/polyphenylene sulfide
The material response of a graphite/polyphenylene sulfide (thermoplastic) composite system to a variety of loadings was experimentally investigated. Quasi-static tension tests were performed on specimens cut from unidirectional panels at angles of 0°, 90°, and 10° in order to the find material …
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A Lagrangian, Discontinuous-Galerkin Material Response Solver for the Analysis of Ablative Thermal Protection Systems
… during hypersonic flight. One category of TPS materials manages extreme heat through pyrolysis, a process in which the elevated temperatures trigger an endothermic reaction that decomposes the material into char and gases, and through thermochemical ablation, in which char and pyrolysis gases …
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Design, testing, and utilization of a spherical shock-recovery system to investigate material response to ultrahigh pressure
… systems are used extensively in the study of materials under high pressure. However, a three-dimensional system capable of substantially higher pressure with the capability of full sample recovery would add a new dimension to the analysis of materials exposed to ultra-high shock pressure. In …
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Constitutive modeling of advanced thermoset composites with application to sheet forming processes
… thermoset composites are an important class of materials employed primarily in aerospace applications that consist of a thermoset polymer resin matrix that is reinforced by systematically arranged, continuous graphite fibers. Composite sheet forming, or thermoforming, is a process where flat …
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Uncertainty quantification of vista charring ablator material database using Bayesian inference
… have been shown to be unable to fully replicate material response data recorded during flight. Collaborative efforts aimed at improving current models are also difficult to establish due to restrictions placed on the access to material response data. In response, a material model free of access …
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Nondestructive Analysis of Advanced Aerospace Materials via Spectroscopy and Synchrotron Radiation
Advanced aerospace materials require extensive testing and characterization to anticipate and ensure their integrity under hostile environments. Characterization methods utilizing synchrotron X-Ray diffraction and spectroscopy can decrease the time required to determine an emerging material's …
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A Numerical Study of Intergranular and Oxidation-Driven Fracture in an Elastic-Viscoplastic Material
… that is believed to be important in the fatigue response of high-temperature superalloys: intergranular fracture driven by the infiltration and embrittlement of grain boundaries by oxygen. A novel space-time finite element model is developed to study this mechanism. The numerical model provides …
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Comparison of nonlinear finite element formulations: application to trusses
… are reviewed. An introduction to different material response measures suitable for nonlinear analysis, in addition to an overview of the Total and Updated Lagrangian reference frames, serve as the starting point for this review. The two nonlinear formulations are specialized for use with a …
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Design tools for linear viscoelastic fluids
… design often makes use of conventional materials such as hard, elastic solids and simple, Newtonian fluids. Rheologically-complex materials (non-Newtonian fluids and soft solids) demonstrate useful and novel properties in both engineered and biological systems. Incorporating these …
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Active Measurement of a Micron-Order Gap Under High-Speed and High-Temperature Conditions
… between the harsh environment and surface materials of these flight bodies. The mechanical operation of a portable hypersonic simulation device was developed in-house and tested at Argonne National Laboratories (ANL) to gather in-situ material response of prospective UHTC samples when …
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Finite element analysis of shear resistant mechanisms for biolaminate interfaces
… and a compliant bone inner layer with all materials exhibiting a decreasing elastic modulus, yield strength and density through the thickness. Experiments on ganoid scales revealed properties such as damage mitigation and energy dissipation that are unique to biological dermal armor. The …
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A laboratory simulation of low velocity projectile impact on thin plates
… and provide an accurate means of analysing a material response to projectile impact events. A low velocity apparatus, based on the conventional instrumented drop tower apparatus, was designed and constructed. The apparatus is instrumented in order that the penetration resistance force history …
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Dynamic mechanical analysis of graphite/epoxy composites with varied interphases
… been used extensively to characterize polymeric materials. This thesis investigates the use of this technique to characterize composite materials. Four material systems, all having the same fiber and the same matrix material, were systematically altered with different interphase regions. Initial …
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Design and analysis of transient nonlinear coupled systems
… problems includes systems with history dependent material response, e.g. plasticity. The traditional finite element analysis is combined with sensitivity analysis and numerical optimization to obtain a systematic design algorithm. Sensitivities for a generalized response function are formulated …
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ULTRA-HIGH STRAIN RATE CONSTITUTIVE MODELING OF PURE TITANIUM USING PARTICLE IMPACT TEST
… particle impact test, it is possible to study materials mechanics under extremely high deformation rates, i.e., above 10^6 s^-1, a relatively less explored regime of strain rates. In this study, we accelerate microparticles of commercially pure titanium to ~100 m/s towards a rigid substrate and …
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The dynamic stability characteristics of damage-prone systems
… experiencing large deformations and inelastic material response with damage, is presented. Because the differential equations that describe the motion are highly nonlinear and coupled for the multi-degree-of-freedom system, a numerical procedure was employed to determine the response. While …
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Making Humanitarian Spaces Global: Coordinating Crisis Response through the Cluster Approach
… spaces are being made through the socio-material practices associated with the Cluster Approach for the coordination of humanitarian action. Drawing on in-depth interviews with humanitarian professionals from the UN, the Red Cross/Red Crescent Movement and various humanitarian NGOs, …
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Holonomic Elastoplastic Truss Design Using Displacement Based Optimization
… was applied to truss design problems with material nonlinearities, to explore feasibility and verify efficiency of the approach to solve such problem. Various truss sizing problems with holonomic (path-independent) elastoplastic laws were investigated. This type of material nonlinearity …
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Carbon Nanotube Mechanics: Continuum Model Development from Molecular Mechanics Virtual Experiments
… hold great promise as an important engineering material for future applications. To fully exploit CNTs to their full potential, it is important to characterize their material response and ascertain their material properties. We have used molecular mechanics (MM) simulations to conduct virtual …
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