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 11 of 11 for “"Equivalent Plastic Strain"”.
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Equivalent plastic strain for the Hill's yield criterion under general three-dimensional loading
… constitutive models for the prediction of plastic failure and ductile fracture. In this thesis, a derivation of the equivalent plastic strain for plane stress in matrix notation is presented using associated plastic flow and work conjugation. A similar method is attempted for the general …
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Investigation of Taylor impact test of isotropic and anisotropic material through geometrical characteristics of specimens
In this thesis, high strain rate properties of isotropic material (a copper alloy) and anisotropic material (2195-T8 aluminum-lithium alloy) are investigated using Taylor impact tests. Coordinate measuring machines (CMMs) are used to measure the shape of specimens after the deformation. The …
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Formulation, analysis and solution algorithms for a model of gradient plasticity within a discontinuous Galerkin framework
An investigation of a model of gradient plasticity in which the classical von Mises yield function is augmented by a term involving the Laplacian of the equivalent plastic strain is presented. The theory is developed within the framework of non-smooth convex analysis by exploiting the equivalence …
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Fracture prediction in metal sheets
… criterion formulated in terms of the accumulated equivalent plastic strain with the stress triaxiality as a weighting function is considered. Using the equations of plane stress von-Mises plasticity and the strain-to-stress mapping procedure, the BW fracture criterion is transformed to the spaces …
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Indentation Behavior of Multilayer Al/SiC Thin Films
… of the indenter to the undulation. The amount of equivalent plastic strain in the Al layers also increases in the presence of undulating layers. These multilayer films exhibit interesting and complex mechanical behavior under indentation type loading and unloading. The derivation of Young's …
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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.
… directions, resulting in a dataset of 321 stress-strain curves. Morphologies were generated via simulated spinodal decomposition, allowing controlled variation of anisotropy. Explicit finite element simulations, validated against experimental data, revealed that plastic energy dissipation …
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The influence of rough rolling conditions on austenite evolution in peritectic microalloyed plate steels
… In this work the influence of the strain sequence during roughing on the evolution of austenite in plain carbon, C-Mn-V, C-Mn-Nb-V and C-Mn-Nb-Ti-V steels, was investigated during conventional hot rolling. This was done because strain is one of the most controlling parameters of …
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Ductile fracture at intermediate stress triaxialities : experimental investigations and micro-mechanical modeling
… thereby requiring reliable models for plasticity and fracture. This thesis reports on a comprehensive investigation into the effect of stress state on the onset of ductile fracture of an Advanced High Strength Steel (AHSS), covering development of new experimental procedures, material …
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Non-Linear Finite Element Method Simulation and Modeling of the Cold and Hot Rolling Processes
… slab and the steel rolls. The model predicts the equivalent stress, equivalent plastic strain, maximum strain rate, equivalent total strain, slab temperature increase, increase in roll temperature, strip length increase, slab thickness % reduction (draft), and strip's velocity increase, for both …
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Ductile fracture after complex loading histories : experimental investigation and constitutive modeling
… practice, sheet metal often fails after complex strain paths that deviate substantially from the widely studied proportional loading paths. Different from previous works on the ductile fracture of sheet metal, this thesis research addresses the experimental and modeling issues related to the …
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Transients in Polymer Electrolyte Membrane (PEM) Fuel Cells
The need for energy efficient, clean and quiet, energy conversion devices for mobile and stationary applications has presented proton exchange membrane (PEM) fuel cells as a potential energy source. The use of PEM fuel cells for automotive and other transient applications, where there are rapid …