Description:
Following generally accepted axioms and assumptions the authors developed a phenomenological, thermodynamically
consistent material model for large anisotropic elastoplastic deformations based on a substructure concept.
The material model originally includes a stress relation in rate formulation, evolutional equations for the
internal variables modeling the hardening behavior, and the yield condition. Due to the necessary time
discretization solving the initial value problem (IVP) this approach is associated with an incremental
stress computation. It will be shown that, within this context, the accuracy of stress values
essentially deteriorates with increasing load steps. Consequently, the authors substitute the usual
stress relation including the symmetric plastic strain tensor of right Cauchy-Green type instead of the
stress tensor into the set of unknown constitutive variables. Stresses are explicitly computed from a
hyperelastic material law depending on the elastic strain tensor. Furthermore, as an alternative to the
plastic strain tensor the solution of the IVP considering an
evolutional equation for the plastic part of the deformation gradient has been studied.
This procedure simplifies the mathematical structure of the system to be solved as well
as the computation of substructure-based variables which are suitable for the analysis
of texture development. The presented numerical strategies were implemented into an in-house FE-code.
Some examples illustrating their accuracy, stability as well as efficiency are discussed.