The total stress response of material is decomposed into a sum of an equilibrium stressresponse and a non-equilibrium overstress response.Correspondingly,the rate-independent intrinsictime and the rate-dependent intrinsic time are defined respectively.Additional hardening functions fordescribing the isotropic and anisotropic nonproportional effects are assumed to be related to the accumu-lation of plastic strain component along the normal of equilibrium stress trajectory,in which the effectsof geometry of the loading path are included.An endochronic constitutive model for rate-dependent,nonproportional cyclic plasticity is formulated and applied to simulate the stress responses of stainlesssteel XCrNi18.9 for some typical loading programs at different loading rates.A comparison betweenpredicted results and experimental ones by Haupt and Lion shows that the former are in agreement withthe latter.
