AN INTERNAL VARIABLE MODEL OF VISCOPLASTICITY

A time and temperature dependent plasticity model is formulated in a Lagrangian system to describe finite deformation. The history dependence and large strain behavior are incorporated through the introduction of one tensor internal variable. Linear decomposition of the stretching tensor into elastic and plastic parts is assumed and a constitutive equation is formulated for the plastic stretching which predicts a pseudo yield point. The model assumes a temperature change based upon the occurrence of adiabatic processes. Model prediction in comparison to strain rate change tests and tension and torsion tests is discussed.