On the relations between strain and strain-rate softening phenomena in some metallic materials: a computational study

It is shown that in certain materials plastic instabilities of different ty pes may be traced back to the same physical mechanism. Depending on experim ental conditions, transitions between various types of instability may take place, i.e., the classification of plastic instabilities may in those situ ations reflect parameters of the experimental setup rather than the intrins ic properties of the material. This is demonstrated for a theoretical model (the Ananthakrishna (AK) model) developed for the description of the Porte vin-le Chatelier (PLC) effect. The results of numerical experimentation on the AK model are compared to the existing experimental data and discussed i n terms of classifications of plastic instabilities that have been proposed in the literature. (C) 1999 Elsevier Science B.V. All rights reserved.