An implicit staggered algorithm for CPFEM-based analysis of aluminum

In this paper, we propose an implicit staggered algorithm for crystal plasticity finite element methodwhich makes use of dynamic relaxation at the constitutive integration level. An uncoupled version ofthe constitutive system consists of a multi-surface flow law complemented by an evolution law for thehardening variables. Since a saturation law is adopted for hardening, a sequence of nonlinear iterationfollowed by a linear system is feasible. To tie the constitutive unknowns, the dynamic relaxation method isadopted. A Green-Nagdhi plasticity model is adopted based on the Hencky strain calculated using a[2/2] Padé approximation. For the incompressible case, the approximation error is calculated exactly.A enhanced-assumed strain element technology is adopted, which was found to be especially suitedto localization problems such as the ones resulting from crystal plasticity plane slipping. Analysis ofthe results shows significant reduction of drift and well defined localization without spurious modes orhourglassing.