FORMULATION OF VISCOPLASTICITY LAWS USING OVERSTRESSES

In the present paper, general definitions for viscoelasticity and visc oplasticity laws are introduced. In addition, two methods for formulat ing viscoplasticity laws are given. These methods are based on two dif ferent notions of overstresses, introduced here with reference to the 3-parameter solid, and can take into account various kinds of non-line arities. For the viscoplasticity laws considered, as well as for limit ing cases of these laws, an analysis of the functional structure is pe rformed; in addition, characteristic properties are illustrated, using one-dimensional loading histories.