Dynamic Strain Aging, Negative Strain-Rate Sensitivity and Related Instabilities

Abstract

We give in this paper a possible mechanical interpretation to the development of L¨uders front and Portevin-Le-Chatelier effect based on a band analysis for an elastic- viscoplastic material with negative strain-rate sensitivity. This negative strain rate sensitivity allows for jumps for the plastic strain rate which in turns permits the existence
of localization bands for the elastic-viscoplastic material. The classical band analysis for an infinite solid does not predict the direction of the band. However, we show that this direction is determined in some circumstances if one considers the boundary conditions.