The Incorporation of Discrete Deformation Twins in a Crystal Plasticity Finite Element Framework

The most prevalent twinning models homogenize the local deformation response by considering twins as “pseudoslip” systems, obscuring the physical differences between slip and twinning—namely the discrete nature of twinning. Presented is a computational approach designed to consider discrete deformation twinning in a crystal plasticity finite element framework. A polycrystalline domain is pre-discretized at the sub-grain scale into lamellar regions dependent on the geometry of the twin systems, which facilitates a finite element mesh that is attendant to this geometry. A twin is activated in a lamellar region by applying essential velocities to its nodes and rapidly mapping their locations to their expected twinned positions. The rest of the body deforms by crystallographic slip to enforce mechanical equilibrium. Results indicate stress relaxation in the parent grain and regions of large stress concentrations in neighboring grains. These trends are discussed in light of global and local energetic observations.