Crystal-based simulations in transformation thermomechanics of shape memory alloys

A crystal-based finite element model is proposed to simulate the thermomechanical behavior of shape memory alloys. Martensitic/reverse transformations are assumed to start when the transformation conditions are satisfied on one of the 24 possible habit planes in a single crystal. A pseudoshear deformation is associated in the corresponding variant, and the stress/strain fields are induced in the polycrystal which is an aggregate of the single crystals. The stress–strain–temperature response is simulated under complex thermomechanical loads, revealing that the macroscopic performance is directly influenced by the elementary transformation/deformation process progressing on the habit planes. The initial and subsequent transformation conditions are determined on the axial stress-shear stress plane, which suggests the concept of “isotropic” and “kinematic” hardening similar to plasticity.