AN ANALYSIS OF RATE-DEPENDENT AND MATERIAL PARAMETER-DEPENDENT LIMITING CASES IN VISCOPLASTICITY LAWS

With reference to a well known viscoplasticity law, it is shown how th e equilibrium curve associated with a process can be determined. Furth ermore, for this viscoplasticity law, an analysis is given for the rat e- and material parameter-dependent limit response. In particular, it turns out that for very slow motions, the strain-stress relation conve rges everywhere to a plasticity model. However, the time derivatives o f the variables in this plasticity law are not everywhere equal to the limit for very slow motions of the corresponding time derivatives in the viscoplasticity law.