Thermodynamic theory of dislocation-mediated plasticity

Unravelling the physics of size-dependent dislocation-mediated plasticity

Size-affected dislocation-mediated plasticity is important in a wide range of materials and technologies. Here we develop a generalized size-dependent dislocation-based model that predicts strength as a function of crystal/grain size and the dislocation density. Three-dimensional (3D) discrete dislocation dynamics (DDD) simulations reveal the existence of a well-defined relationship between str...

Dislocation Plasticity: Overview

An arbitrary deformation of a material can always be described as the sum of a change in volume and a change in shape at constant volume (shear). Assuming constant structure, the change in volume is recovered when the load is removed, since the atoms can simply relax back to their equilibrium sizes. The change in shape, on the other hand, may or may not be recovered, since the atoms can relax i...

Dislocation core effects in plasticity

Micro-plasticity of surface steps under adhesive contact: Part II – Multiple-dislocation mediated contact hardening

The study of the micro-plastic behavior of rough surface contact is the critical link towards a fundamental understanding of contact, friction, adhesion, and surface failures at small length scales. In the companion paper (Yu et al., J. Mech. Phys. Solids 55, 489-516, 2007), we have studied the onset of surface yielding due to single-dislocation nucleation from a stepped surface under adhesive ...

Gradient Theory for Plasticity as the Γ-limit of a Nonlinear Dislocation Energy

In this paper we rigorously derive a strain-gradient theory for plasticity as the Γlimit of a nonlinear mesoscopic dislocation energy, without resorting to the introduction of an ad hoc cut-off radius. To our knowledge, this is the first paper to treat a nonlinear dislocation energy. The Γ-limit we obtain as the length of the Burgers vector tends to zero has the same form as the Γ-limit obtaine...