We develop a micromechanical model for single-crystalline materials undergoing diffusionless solid-to-solid phase transitions. It is based on the specification of laminated microstructures on the materials' microscale and hence is designed to approximate the rank-1-convex hull of the underlying energy-density for the phase-mixture. In order to capture the hysteretic behavior of such materials like shape-memory-alloys we also account for dissipation by means of evolution equations for the inelastic internal variables. In this context, we derive different evolution-laws from inelastic potentials via least-action principles. Several material-point computations emphasize the characteristics of the presented model.
Several constitutive models for magnetic shape memory alloys (MSMAs) have been proposed in the literature. The implementation of numerical integration schemes, which allow the prediction of constitutive response for general loading cases and ultimately the incorporation of MSMA response into numerical solution algorithms for fully coupled magneto-mechanical boundary value problems, however, has received only very limited attention. In this work, we establish two algorithmic implementations of the internal variable model for MSMAs proposed in (Kiefer and Lagoudas 2005 Phil. Mag. Spec. Issue: Recent
Adv. Theor. Mech. 85 4289–329, Kiefer and Lagoudas 2009 J. Intell. Mater.
Syst. 20 143–70), where we restrict our attention to pure martensitic variant reorientation to limit complexity. The first updating scheme is based on the numerical integration of the reorientation strain evolution equation and represents a classical predictor–corrector-type general return mapping algorithm. In the second approach, the inequality-constrained optimization problem associated with internal variable evolution is converted into an unconstrained problem via Fischer–Burmeister complementarity functions and then iteratively solved in standard Newton–Raphson format. Simulations are verified by comparison to closed-form solutions for experimentally relevant loading cases.
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