On a certain type of finite strain viscoelastic-plastic constitutive relationships

In this work a certain type of viscoelastic-plastic constitutive relationships is analyzed. The finite element (FE) implementation is extensively discussed and the consistent tangent operator has been derived. The capability of the present model formulation to capture the large strain and rate-dependent response of polymeric materials is investigated. It is found that a viscoelastic-plastic model utilizing the stored-energy function as proposed by Jemio lo and Lopez-Pamies allows to accurately capture the material behavior for a wide spectrum of stretches and deformation rates. The material parameters of the model have been identified for three different polymeric materials. A UMAT (User MATerial) subroutine has been developed shich enables to use the considered model class within the non-commercial FE program CalculiX.