A nonlinear constitutive model of magneto-thermo-mechanical coupling for giant magnetostrictive materials

The magnetostrictive strain-applied field curve typical of giant magnetostrictive materials is nonlinear and it is affected notably by prestress and temperature. A constitutive model to describe these properties is suggested in this paper. The model considered here is built on the Gibbs free energy function G(σij,Mk,T). Thermodynamic relations are used to obtain the constitutive expressions. Results based on the model show that the nonlinear property of magnetostrictive strain, the magnetization, and Young’s modulus under different prestress and temperature are in excellent agreement with experimental data. Moreover, the proposed model is convenient to be used in engineering applications since the parameters referred to the model can all be easily determined by experiments.