ABSTRACT
In practical engineering systems, various other types of materials are used apart from the most often used linear elastic materials. One example of such a type of materials is the so-called viscoelastoplastic materials [1]. Currently, mechanics problems for solids of viscoelastoplastic materials can be modeled using the FEM, based on the so-called dual formulation or primal formulation. In the dual formulation [2], the displacement and stress approximations are computed simultaneously with yield functions and flow rules written in terms of admissible stresses. In the primal formulation [2], the strains are treated as the primary variables and a discretization is required for simultaneous approximations of both the displacement and plastic strain fields.
