PLASTIC DEFORMATION OF HARDENING MATERIALS UNDER CYCLIC LOADINGS WITHIN THE FRAMEWORK OF THE SYNTHESIS PLASTICITY THEORY

The possibilities of the synthetic plasticity theory developed previously [1] were demonstrated in the description of the plastic deformation for proportional [2] and complex process of loading along a trajectory having the form of a two-segment broken line [1]. In doing so, only active paths of loading without changing the sign of the stress were considered. It was assumed that, within the framework of the model thus constructed, there are no essential difficulties for studying the behavior of materials subjected to cyclic deformation. However, in the description of cyclic loadings, it turned out that some difficulties occur and the created model of plastic medium requires completion and development. In the present paper, the constitutive relations of the synthetic plasticity theory [1] are generalized for studying the plastic deformation of materials under sign-variable and complex loading so as to make this theory applicable to the investigation of the plastic deformation of materials subjected to a loading changing in sign and/or to a complex cyclic loading.