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 14 of 14 for “"Microvoids"”.
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Micro-computed tomography for interlaminar analysis, void quantification, and feature localization in carbon fiber composites
… macrovoids (volumes greater than 100 lim3) and microvoids (volumes less than 100 [mu]m 3) and localizes each void to the interlaminar or intralaminar regions. Macrovoids are studied in extant void quantification literature using optical or SEM inspection of cross-sections, but the small …
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Evaluation of Cold Spray Process for Solid-State Welding
… counterpart due to the presence of ubiquitous microvoids resulting from inadequate metallurgical bonding in CSWed area. These microvoids act as initiation sites for microcracks. To guide future optimization efforts, a failure mechanism in the CSWed parts is established. This research …
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Efeito do envelhecimento e da geração de “whitening” no comportamento mecânico do PVDF
… is associated with cavitation process (growth of microvoids). This work has the objective of studying the effect of PVDF aging in petroleum during 30, 90 and 180 days at 80 ° C and the generation of whitening that was generated by traction tests by cyclic loading. Test specimens were aged in …
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Tensile and fracture behaviour of isotropic and die-drawn polypropylene-clay nanocomposites. Compounding, processing, characterization and mechanical properties of isotropic and die-drawn polypropylene/clay/polypropylene maleic anhydride composites
… may undergo either an increase in the size of microvoids at low clay loading or coalescence of microvoids at high clay loading, eventually leading to an earlier failure than with neat PP. The adoption of PPMA loading using an appropriate mixing route and clay loading can create a balance …
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Crack Healing in Polymers (Fracture, Reptation, Tack)
… of crazes in atactic polystyrene (PS) and microvoids in styrene-isoprene-styrene block copolymers was described phenomenologically, from dark-field optical microscopy and light transmission measurements. For the healing of bulk polymer surfaces, molecular-level models were coupled with …
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Elastic-Damaging Plasticity Model for Ductile Fracture
… process of nucleation, growth and coalescence of microvoids or microcracks. However, the model uses a continuum approach that can capture the global effect of ductile fracture behavior. It consists of two uncoupled material models; an elastic-damaging model that employs continuum damage mechanics …
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Tailored Mechanical Response of 3D Microgranular Crystals with Hierarchical Architecture
… media across both grain-level (ellipsoidal microvoids) and bulk granular packing-level architectures, offering surprising control over static and dynamic properties. Using nanoindentation experiments, we reveal tunable quasi-static stiffness behavior, where hollow architected granular …
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Ethanol from photoperiod-sensitive sorghum: a study on biomass structure and process optimization
… scattering result of the increased length of microvoids. The results from WAXD also suggested a simultaneous hydrolysis and crystallization of cellulose by acid.
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Microstructural Modification in Nanocrystalline Silicon Due to Selective Charge Injection: A Current-sensing Atomic Force Microscopy Study
… bonds released hydrogen atoms into microvoids where hydrogen molecules formed causing volumetric changes in the film. In conclusion, it was observed that RF sputtered nc-Si:H films had a large amount of weak and strained bonds which could be broken to create defects making it …
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Effects of collagen content, fiber alignment, storage and heating on cooking characteristics, dimensional changes and microstructure of restructured beef
… provides strength to support the dome; and 6) "microvoids" exist within the dome with larger voids in the vicinity of the dome. A possible mechanism for channel development is based upon the following observations: 1) sufficient layers of parallel muscle fibers are lacking; 2) insufficient …
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An investigation of defect formation and growth in epoxy resin using light scattering methods
… It was discovered that inhomogeneities and microvoids do exist in the fully cured and degassed ultra clean samples before stressing. Reproducible trends in inhomogeneity behaviour were observed on stressing, and a three phase model of inhomogeneity has been proposed to explain this …
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Experimental and Computational Micromechanics of Aluminum Cerium Alloys and Selective Laser Melted 316L Stainless Steel
… failure process is determined to be coalesce of microvoids leading to ductile damage failure. These results are used to create an experimental-computational framework to develop a crystal plasticity finite element model for extruded Al-8Ce-10Mg alloys. The calibrated model is used to perform …
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Modeling the effect of boron on microdefect formation
… from a self-interstitial rich external ring. Microvoids form in the core by vacancy aggregation. Dislocation loops form in the self-interstitial rich region. The presence of dopants in the crystal also affects microdefect distributions by interacting directly with self-interstitials and …
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The Effects of Load Ratio on Threshold Fatigue Crack Growth of Aluminum Alloys
The integrity of nearly all engineering structures are threatened by the presence of cracks. Structural failure occurs if a crack larger than a critical size exists. Although most well designed structures initially contain no critical cracks, subcritical cracks can grow to failure under fatigue …