Subloading-Overstress Model: Unified Constitutive Equation for Elasto-Plastic and Elasto-Viscoplastic Deformations Under Monotonic and Cyclic Loadings Research with Systematic Review

Various elasto-plastic models for the rate-independent deformation, various elasto-viscoplastic models for the rate-dependent deformation and their combinations have been proposed during a long time more than one or more centuries. Firstly, the history of the development of the elastoplasticiy and the elasto-viscoplasticity is reviewed comprehensively. Unfortunately, each of these models possesses their own drawbacks and limitations. The unified constitutive equation of the elasto-plastic and the elasto-viscoplastic deformations is provided by incorporating the subloading surface model into the overstress model in this article, which is capable of describing the monotonic and the cyclic loadings at the general rate ranging from the quasi-static to the impact loading. The validity of the unified model is verified by the comparison with various test data of metals under various loading conditions. Consequently, the elastoplastic constitutive equation can be disused hereinafter, while it is expressed by the cumbersome formulation including the complicated plastic modulus but limited to the description of the purely static deformation which is not induced actually.