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 22 for “"elastic regime"”.
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Effects of Fatigue in the Elastic Regime on the Mechanical Properties of Nuclear Pressure Vessel Steels
Made available in DSpace on 2017-07-06T18:56:02Z (GMT). No. of bitstreams: 3 Riedy_Alexander_W_MS.pdf: 57625324 bytes, checksum: a63828112673c0818a625c2ee346d239 (MD5) Riedy_Alexander_W_MS_ABS.pdf: 941457 bytes, checksum: a3bbb5cf4be77548e913c9b5bf833253 (MD5) license.txt: 4813 bytes, checksum: …
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Effects of Fatigue in the Elastic Regime on the Impact Properties of Nuclear Pressure Vessel Steels and Its Relation to Fracture Toughness
Made available in DSpace on 2017-07-06T18:49:10Z (GMT). No. of bitstreams: 3 Canty_Robert_W_MS.pdf: 44893344 bytes, checksum: 36b04769a61e51628aa6cd3ec4b26d75 (MD5) Canty_Robert_W_MS_ABS.pdf: 529441 bytes, checksum: bdae3bda0f7e90e23a00e5d0439f8a81 (MD5) license.txt: 4813 bytes, checksum: …
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Bifurcação secundária instável em placas retangulares
The non-linear elastic behaviour in thin flat plates under the effects of initial imperfections and coupled modes is analysed in the presented work. Through this analysis it is detected, along the imperfect fundamental equilibrium path, secondary points of bifurcation which may be stable or …
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A mechanically-derived contact model for adhesive elastic-perfectly plastic particles
… to capture the response of interacting adhesive elastic-perfectly plastic particles under a variety of loadings is presented. The contact model is valid through each of the three major contact regimes: elastic, fully-plastic, and bulk elastic---all with and without adhesion. In the elastic …
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Interação do hidrogênio com a microestrutura dos aços inoxidáveis supermartensíticos sob regime elástico
… the microstructure of the Super 13Cr steel under elastic loading. For the purpose of this work, hydrogen study, microstructure characterization and uniaxial tension tests (especially with hydrogenated samples under uniform stress) were made cooperatively with numerical analyses. The hydrogen …
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Experimental study of the development of plastic solitary waves in one-dimensional granular media
… these systems which have been conducted in the elastic regime – cause the granular chains to deform plastically. These conditions allow for solitary waves, which propagate in the one-dimensional array of elastic spheres, to be studied in the plastic regime. The propagating pulse assumes a …
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Dynamics and statics of actin assemblies
… and mechanical energy and show that the stored elastic energy alone is sufficient to drive the reaction. We also provide an estimate of the maximum force generated during the uncoiling by stalling the bundle using an agarose gel. Finally, we provide a simple mathematical model that rationalizes …
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Mechanics of proton exchange membranes : time, temperature, and hydration dependence of the stress-strain behavior of persulfonated polytetrafluorethylene
… temperature, and hydration dependence of the elastic regime, yield, strain hardening, and stress relaxation at low to moderate strains.
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Mechanical behavior of nanostructured metallic films under compressive and shear loads
… the amount of energy stored in the films in the elastic regime. A spring index, which is the ratio of the mean coil diameter to the wire diameter, of 2.5-3 was found to maximize the amount of elastic spring energy stored in a nanostructured film under uniform compressive loading and an index of …
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As global ambient temperatures continue to rise, with the highest recorded annual averages since 1850 being within the last ten years, problems emerge for species exhibiting temperature-dependent sex determination. This is the process by which the sex of an animal’s embryo is determined based on the temperature of environment in which it is incubated, which can result in skewed sex ratios within a population like in the case of the critically endangered Hawksbill Sea Turtles (Eretmochelys imbricata). Reportedly, 85-95% of Hawksbills sampled in the wild are currently female [3]. This sex-imbalance can negatively impact the species’ ability to procreate, leading to the potential for extinction. Currently, no viable, long-term solutions exist to effectively and safely cool sea turtle eggs while still keeping them within their natural habitat. This research proposes the creation of sea turtle egg incubators designed to achieve a temperature range that will produce a higher percentage of male hatchlings to help rectify this imbalance in habitats heavily affected by climate change. These incubators are designed to be affordable, easy to build and, most importantly, safe for the sea turtle eggs. Three-month-long temperature trials for the incubator were conducted in Jamaica with conservationist community partners at Oracabessa Bay Sea Turtle Project. Results showed that this incubator is not only easy to manufacture and use, but that it successfully regulates the temperature range in favor of more male hatchlings, while also increasing the emergence rate of the hatchlings from 70% in natural nests to over 80%. During one of the hottest months in Jamaica, the incubator, deployed without water changes, doubled the predicted percentage of males produced by natural nests. When provided with cool water changes the incubator quintupled this value. Throughout the months of August to October, the incubator achieved a temperature range that is predicted to produce 85-99% male hatchlings, thus counteracting the feminization phenomenon occurring in nature.
… Nevertheless, their behavior beyond the elastic regime remains largely unexplored. This thesis investigates the nonlinear mechanics of spinodal architected materials by combining a comprehensive experimental dataset with computational modeling. A total of 107 unique morphologies were …
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Failure mechanisms of thermal barrier coatings for high temperature gas turbine components under cyclic thermal loading
… approach, based on the principles of linear elastic fracture mechanics. In contrast to conventional microscopic damage analysis of APS TBCs, two non-destructive methods were applied for investigation of EB-PVD TBCs: - Grey scale analysis for the evaluation of thermal strains at the surface of …
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Stress Corrosion Cracking of a Transformation Induced Plasticity Fe39Mn20CO20Cr15Si5Al1 High Entropy Alloy
… Under a constant load experiment within the elastic regime (26% of yield strength), the passivation film formed exhibited differences in thickness and chemical composition. The passivation film formed under no-load and load conditions consisted of Cr hydroxide and Cr oxide rich, respectively. …
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On the quasi-static and dynamic crushing of random foams
… that exhibits a relatively stiff linearly elastic regime that terminates into a load maximum; it is followed by an extended load plateau during which localized cell crushing initiates and gradually spreads throughout the specimen. When most of the cells are crushed the densified material …
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Multiscale characterization of thermoacoustic response and fatigue failure of aerospace structures
… environment to assess behavior beyond the linear elastic regime and promote plasticity and failure. Although fatigue failure was suppressed in thin beams and panels, adding a stress concentrator, such as a notch near the beam root, promoted fatigue crack nucleation.
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Structural heterogeneity in silk fibers and its effects on failure mechanics and supercontraction
… It is shown that under shear stresses beyond the elastic regime, silk undergoes an [alpha] -- [beta] transition in the spinning duct. The stability of the assembled [beta]-sheet structure seems to arise from a close proximity of the [alpha]-helices in the silk solution. The smallest molecule size …
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Impact of stability and surface area on fracture toughness of biological structures
… discrete structures are modeled with a linear-elastic regime and a von Mises stress failure criterion. We show that the results of these separate analyses agree well with those performed using phase field on the continuum, despite the limitations associated with the conversion from continuum to …
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Evolution of the structure and properties of thermomechanically-processed metallic glasses
… processes involving strain within the nominally elastic regime. This can be achieved through cryogenic thermal cycling (CTC) or elastostatic loading (EL). In the present work, the structural evolution induced by CTC was explored in depth. Four MG-forming compositions and different initial states …
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Thermomechanical Processing of Metallic Glasses
… and different aspects were investigated. From elastic bending experiments on a La-based MG ribbon, TC was observed to accelerate the relaxation of anelastic strain. Nanoindentation measurements on a CuZr-based MG plate showed that TC decreased the yield stress, but barely affected the hardness …
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A Methodology For Instrumented Indentation Studies Of Deformation In Bulk Metallic Glasses
… technique, conducted generally on a sub-micron regime, the depth of penetration of an indenter, usually a diamond, is measured as a function of the applied load and expressed graphically as load (P) - displacement (h) curves from which a host of mechanical properties can be extracted and …
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Biomineralized Composites: Material Design Strategies at Building-Block and Composite Levels
… under tensile and compressive loadings in the elastic regime, while the high-density intracrystalline nanoinclusions contribute to the conchoidal fracture behaviors (instead of brittle cleavage). In comparison, the interlocking grain boundaries in S. woodiana prisms correlate with easier …
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