Modeling of the Stress- and Magnetic Field-Induced Variant Reorientation in MSMAs

Abstract

This paper is concerned with the modeling of the magnetic shape memory alloy (MSMA) constitutive response caused by the reorientation of martensitic variants. Following a summary of the constitutive model previously proposed by the authors, the nonlinear and hysteretic strain and magnetization response of MSMAs are investigated for two main loading cases, namely the magnetic field-induced reorientation of variants under constant uniaxial stress and the stress-induced reorientation under constant magnetic field. It is demonstrated in this work that the model captures the loading history dependence of the constitutive behavior through the evolution of internal state variables. Complex loading cases are also presented in which the sequence of the application of the stress and magnetic field strongly influences the predicted response. The relation of critical stresses and magnetic fields for the activation of the reorientation process are visualized in a variant reorientation diagram on which the considered loading paths are superimposed.