an important concern in rock mechanics is non-homogeneity as joints or fault. this noticeable feature of failures in rock is appearance of slip surfaces or shear bands, the characteristics of that are associated with deformation being concentrated in a narrow zones and the surrounding material remaining intact. adopting the joints as fractures, fractures are well known for their effects on the ...

The stress–strain response of a Fe–17.5Mn–0.7C–2Al TWIP steel during cyclic loading has been investigated by means of tension–compression tests within the strain limits of 72%, 75% and 710%. In addition, the microstructural evolution during the 75% cyclic test has also been studied. The difference between the forward and reverse stress for each pre-strain has been analyzed at 0.2% offset strain...

We studied three-dimensional transient large coupled thermomechanical deformations of a polycarbonate (PC) plate with a through-the-thickness inhomogeneity at its centroid. The PC exhibits strain softening followed by strain hardening and its elastic moduli are taken to be functions of strain rate and temperature. The inhomogeneity is either a void or a region of initial temperature higher than...

Classical continuum models exhibit strong mesh dependency during strain softening. For such materials, the phenomenon may be regularized via the gradient-enhanced nonlocal formulation. The paper discusses the implicit gradient framework and demonstrates that standard nonlocal enhancement may serve only as a partial localization limiter. The over-nonlocal approach, where the weight for the nonlo...

For metals it is widely accepted that the stress-strain diagram is symmetric with regard to tension and compression when plotted in terms of true rather than nominal quantities. Kinematic considerations state that the engineering definition of nominal strain exhibits fundamental deficiencies under rigid body rotations and deformations which are not truly infinitesimal. For these two reasons the...

Center for Concrete and Geomaterials, Northwestern University, Tech-241 0, Evanston, I L 60208 A recent nonlocal damage formulation, in which the spatially averaged quantity was the energy dissipated due to strain-softening, is extended to a more general form in which the strain remains local while any variable that controls strain-softening is nonlocal, In contrast to the original imbricate no...

The mechanical properties of materials are highly sensitive to the content impurities and point defects due their interaction with plastic deformation carriers-dislocations. This opens up possibility some extent control through alloying creating solid solutions. In a number crystalline materials, in addition well-known solid-solution strengthening region low concentration solution atoms, opposi...

Localization of plastic strain induced by softening can be objectively described by a regularized plasticity model that postulates a dependence of the current yield stress on a nonlocal softening variable defined by a differential (gradient) expression. This paper presents analytical solutions of the one-dimensional localization problem under certain special nonuniform stress distributions. The...

We use the modified smoothed-particle hydrodynamics (MSPH) method to analyze shear strain localization in elasto-thermo-viscoplastic materials that exhibit strainand strain-rate hardening and thermal softening. A homogeneous solution of simple shearing deformations of the body is perturbed and the resulting initial-boundary-value problem analyzed by the MSPH method. It is found that the deforma...

We use Bai’s conservation equation for cracks, and Rice and Tracey’s equation for the growth of a spherical void in an infinite medium to derive an evolution equation for damage in an anisotropic material. It is then used to delineate the instability strain in a thin anisotropic sheet deformed in a plane stress state of deformation, and obeying Hill’s yield criterion. Assuming that strainand st...