On physical foundations of plasticity

Abstract

Complexity of plastic response is caused by the fact that plastically deformed solids are composites with a changing structure. At the mesoscale (μm) a pattern of high and low dislocation density regions is spontaneously formed. The evolution of the composite structures is treated as a consequence of the structuralization process governed by four types of mechanisms: (i) the overproduction of dislocation, (ii) the screening of their elastic fields, (iii) the formation of dipolar dislocation patterns, (iv) the instability transition leading to the formation of subgrain boundaries, dislocation grids, microshear bands, or persistent slip bands. The proposed theoretical model consists of the balance law for the dislocation density of stored dislocations, the relations which determine the average shape of glide dislocations, and the continuum mechanics equations for stress and strain. To demonstrate the capacity of the model some available solutions simulating the mesoscale structure evolution are briefly reviewed.