NONLINEAR DYNAMIC CHARACTERISTICS OF MAGNETIC SHAPE MEMORY ALLOY ACTUATOR

A kind of hysteretic nonlinear model of magnetic shape memory alloy (MSMA) was developed in this paper, and the nonlinear dynamic characteristics of MSMA actuator were investigated. Van der Pol nonlinear item were introduced to interpret the hysteretic phenomena of strain-magnetic field intensity (MFI) curves of MSMA, and the constitutive relationship among strain, stress and MFI was obtained in partial least-square regression method to describe the variation of strain-MFI curves with stress. The result of significance test shows that all of the items in the constitutive model are significant, and the result of forecast test shows that the model can describe the hysteretic nonlinear characteristics of strain-MFI curves of MSMA in different stress well. Based on the MSMA model, the magneto-mechanical coupled model of MSMA actuator was developed, and the relationship between input magnetic signal and output displacement was obtained. The nonlinear dynamic characteristics of MSMA actuator were discussed, and phenomena of accuracy aggravation of MSMA actuator in high-frequency magnetic field were explained. Finally the theoretical results were proved by experiment. The new MSMA model has simple form and is easy to be analyzed in theory, which is helpful for the application of MSMA actuator in engineering fields.