The analysis of inelastic behaviour formulated as an inverse rheological approach

This paper deals with a rheological analysis strategy, developed in order to obtain an adequate characterization of the behaviour of material undergoing a large plastic deformation. Starting from physical and phenomenological considerations, a general rheological constitutive model is chosen and introduced into a finite element simulation of the experimental tests. The rheological analysis is then formulated as an inverse problem and the goal is to find the constitutive parameters which lead to the closest values to a set of experimental data measured under various operating conditions. The least square deviation between computed and measured variables is minimized with respect to the parameters of the constitutive equation for the material. The proposed method is illustrated by application to the torsion and tensile test of a general thermo-viscoplastic material. All rheological parameters defining the consistency and variation in strain rate sensitivity coefficient with the strain or temperature are simultaneously determined starting from a chosen constitutive law.