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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 114 for “"plastic strain"”.
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Evaluation of Local Plastic Strain History in Fatigue
Made available in DSpace on 2014-12-08T23:56:43Z (GMT). No. of bitstreams: 1 6612401.pdf: 2982185 bytes, checksum: d5b08e90e60523ada7dcd41b12eed84e (MD5) Previous issue date: 1966
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Effect of plastic strain on the corrosion of X65 pipeline steel
… Research has shown that areas of increased plastic strain develop within pits which may promote crack initiation and material failure. This paper aims to analyze the impact of increased plastic strain on the general corrosion rate of X65 pipeline steel. Samples of X65 steel cold-rolled to …
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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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Effects of plastic strain history on the properties of stainless steel boiler tube welds
… study of the effects of fabrication history (prestraining, welding and heat treatment) on the mechanical properties of austenitic stainless steel thin wall boiler tubes. These tubes are usually cold bent to shape, and sometimes swaged, prior to interconnection by welding. The bends require …
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Strain Energy Density and Thermodynamic Entropy as Prognostic Measures of Crack Initiation in Aluminum
… in this dissertation explores the cumulative plastic strain energy density and thermodynamic entropy generation up to crack initiation. Plastic strain energy density and thermodynamic entropy generation are evaluated to investigate whether they would be capable of providing a physical basis …
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Identification of defect locations in forged products using the finite-element method
… operations considered, that of plane-strain side-pressing, the finite-element predicted deformation behaviour of 60-40 brass and 7075 aluminium alloy has been compared with experiment. Both visioplasticity and hardness studies have been performed. The macrohardness survey was found to …
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Plastic deformation of gallium arsenide
… to determine the validity of Haasen's model of plastic deformation for GaAs over an extended range of temperatures and to observe the relation between the dislocation density in the deformed samples and the deformation variables. The experimental results show a discrepancy with the predictions …
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Deformation mechanisms in bulk nanostructured aluminum obtained after cryomilling and consolidation by spark plasma sintering
… consolidation process. The samples obtainedwere plastically deformed in uniaxial compression. We show that there is a significant fraction of plastic strain (11%) that can be recovered after unloading. High-energy synchrotron X-ray diffraction experiments revealed that, there is a correlation …
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Ductile fracture modeling : theory, experimental investigation and numerical verification
… is governed by the damaging process along the plastic loading path. A new damage plasticity model for ductile fracture is proposed. Experimental results show that fracture initiation in uncracked ductile solids is sensitive to the hydrostatic pressure and is dependent on the Lode angle. The …
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Finite Element Analysis of Adiabatic Shear Bands in Impact and Penetration Problems
… material is modeled as elastic thermoviscoplastic; the flow stress increases with an increase in the effective plastic strain and effective plastic strain-rate but decreases with a rise in the temperature. An objective of this work is to ascertain when and where a shear band, defined as a …
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Numerical analysis of TSV/micro-bump deformation due to chip misalignment and thermal processing in 3D IC packages
… by examining local stresses and the buildup of plastic strain through series of parametric twodimensional (2D) and 3D finite element method (FEM) simulations. A special case when the solder joint is transformed into an intermetallic compound is also examined. Misalignment induced shearing …
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Overcoming the limits of strain-induced martensitic transformation in metastable face-centered cubic alloys
… martensitic phase transformations activated by plastic straining are considered as one of the most effective pathways to promote strength while preserving desirable ductility. The resultant transformation-induced plasticity effect has enabled great success in advancing steels, titanium alloys, …
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Fatigue of Concrete Beams and Slabs
Strain gages, attached to all specimens tested, indicated cracking in concrete occurred in a narrow band. Regions of high plastic strain were found in the plane of cracking, while adjacent areas experienced decreases in strain levels with cracking. Strain gages indicated cracking in concrete slabs …
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Variational constitutive updates for strain gradient isotropic plasticity
In the past decades, various strain gradient isotropic plasticity theories have been developed to describe the size-dependence plastic deformation mechanisms observed experimentally in micron-indentation, torsion, bending and thin-film bulge tests in metallic materials. Strain gradient plasticity …
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Phase field modeling of the defect evolution and failure
<p>The plastic recovery processes in ultrafine and nano grained metals and the yield criteria and failure mechanisms in polymer matrix composite are the two major topics in this work.</p> <p>In the first part of the work, a phase field dislocation dynamics (PFDD) approach is introduced, which …
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Calculation of Notch Strains Under Multiaxial Nominal Loading
… analytical method is developed to calculate strains at stress concentrators in structures of elastic-plastic, isotropic material subjected to proportional and nonproportional multiaxial nominal loading. The method uses anisotropic plasticity theory to define a structural yield surface in …
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On a class of strain gradient plasticity theories : formulation and numerical implementation
This study develops strain-gradient theories for isotropic and crystal plasticity. The following four theories were developed and numerically implemented: * A one-dimensional theory to understand the basic nature of strain gradient theories; * A small deformation crystal plasticity theory; * A …
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A study of crack initiation in corrosion-fatigue of A.I.S.I 316 stainless steel by dynamic measurement of corrosion characteristics and corrosion current transients
… at slip steps with resultant enhancement in plastic strain and premature crack initiation.
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Experimental investigation and constitutive modeling of the large deformation behavior of anisotropic steel sheets undergoing strain-induced phase transformation
The strain-induced phase transformation from austenite to martensite is responsible for the high strength and ductility of TRansformation-Induced Plasticity (TRIP)- assisted steels. The large deformation behavior of conventional steels is governed by crystallographic slip. In the case of TRIP …
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Anisotropic ductile fracture of metal sheets : experimental investigation and constitutive modeling
Anisotropic mechanical properties are common in plastically deformed or thermomechanically processed metallic materials, e.g. in rolled or extruded sheet. Among them, the anisotropy of large strain plastic deformation and ductile fracture under multi-axial loading is highly relevant to various …
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