-Dislocation theory is used to invoke a strain gradient theory of rate independent plasticity. Hardening is assumed to result from the accumulation of both randomly stored and geometrically necessary dislocations. The density of the geometrically necessary dislocations scales with the gradient of plastic strain. A deformation theory of plasticity is introduced to represent in a phenomenological...

In the present study, crystal plasticity models applicable for reproducing work-hardening behavior under various loading paths of an A5083-O Al alloy sheet were examined. The consideration tension, reverse from compression to simple shear, and biaxial tension. accumulated-slip-based hardening model with extended Voce law provided good predictive accuracy uniaxial loadings. contrast, it could no...

The material properties of OFHC copper film was investigated with the High-Speed Material Micro Testing Machine (HSMMTM) at the high strain rates. The rate-dependent stress-strain curves from the experiment and the Johnson−Cook curve fitting showed large discrepancies as the plastic strain increases since the constitutive model implies no rate-dependent strain hardening effect. A new constituti...

This article addresses the issue of reproducing quantitative pressure-drop predictions for constant shear-viscosity fluids in contraction and contraction/expansion flow geometries. Experimental observations on pressure-drop for severe strain-hardening Boger fluids reveal significant enhancement above Newtonian fluids in axisymmetric but not planar configurations. This discrepancy has eluded pre...

A phenomenological theory is presented for describing the anisotropic plastic flow of orthotropic polycrystalline aluminum sheet metals under plane stress. The theory uses a stress exponent, a rate-dependent effective flow strength function, and five anisotropic material functions to specify a flowpotential, an associated flow rule of plastic strain rates, a flow rule of plastic spin, and an ev...

Abstract: Methods of fault-hardening software implementations of the numerical Model Predictive Control (MPC) algorithms are discussed in the paper. In particular, Generalized Predictive Control (GPC) algorithms are considered. The robustness of these algorithms with respect to faults is crucial for process safety and economic efficiency, as faults may result in major control performance degrad...

This paper proposes and investigates schemes for hardening the conventional CMOS cross-coupled DRAM sense amplifier to single event upset (SEU). These schemes, adapted from existing SRAM hardening techniques, are intended to harden the dynamic random access memory to bitline-mode errors during the sensing period. Simulation results indicate that a 9kΩ L-resistor hardening scheme provides greate...

Despite research spanning several decades, the exact value of the shear modulus Gs of the erythrocyte membrane is still ambiguous, and a wealth of studies, using measurements based on micropipette aspirations, ektacytometry systems and other flow chambers, and optical tweezers, as well as application of several models, have found different average values in the range 2-10μN/m. Our study shows t...

An Aspect-Oriented Framework for Systematic Security Hardening of Software Azzam Mourad, Ph.D. Concordia University, 2008 In this thesis, we address the problems related to the security hardening of open source software. Accordingly, we first propose an aspect-oriented and pattern-based approach for systematic security hardening. It is based on the full separation between the roles and duties o...

P92 steel was irradiated with Ar ion up to 10 dpa at 200, 400, and 700 ◦C. The effect of Ar ion irradiation on hardness was investigated with nanoindentation tests and microstructure analyses. It was observed that irradiation-induced hardening occurred in the steel after Ar ion irradiation at all three temperatures to 10 dpa. The steel exhibited significant hardening at 200 and 700 ◦C, and slig...