Vibration analysis of a nonlinear magnetostrictive actuator

In this paper, the magnetostrictive actuator was analyzed with the nonlinear constitutive equation of magnetostriction and, for comparison, the linear piezomagnetic equation. Theoretical model shows that, for the case of relatively large excitation magnetic field, the nonlinear constitutive equation should be adopted in order to give an accurate prediction in the design of actuators. The actuator resonates not only at the natural frequencies of the vibration system, but also arises when the frequency of the excitation current in the coil equals half of any one of the natural frequencies of the system. This conclusion cannot be reached by the formulation with the linear piezomagnetic equation. It is verified that the results obtained from the nonlinear equation reduce to be that of linear piezomagnetic equation when the amplitude of the excitation magnetic field provided by the coil is very small compared to the bias magnetic field and its frequency does not induce resonance of the system.