Formation, propagation of bands and chaos in jerky flow

Abstract

There has been a renewed interest in understanding instabilities in plastic flow since the introduction of bifurcation theory into the analysis of these instabilities. The principal aim in such attempts is to relate the microscopic dislocation mechanisms to the macroscopic measurable quantities such as the occurrence of the phenomenon in a finite range of strain rates and temperature, etc., and most of all the inhomogeneous nature of the deformation. In this paper, the authors will demonstrate that the simplest spatial dependence in the form of a gradient term in the continuity equations already gives the essential ingredients. Apart from retaining all the predictions of the earlier model, it predicts that the velocity of the Portevin-Le Chatelier (PLC) bands increases with the applied strain rate and decreases with the concentration of the solute atoms. They will also deal with theoretical and experimental characterization of chaotic flow.