Rate-dependent losses modeling for magnetostrictive actuators

The present paper tackles the magnetic field diffusion analysis in thin cylindrical rods of materials showing hysteresis effects and employed in commercial actuators. The problem is formulated in terms of magnetic vector potential. By this formulation the used magnetic constitutive relationship assumes magnetic induction as input. Since almost all of the hysteresis models that can be employed (like the Preisach model) to describe the B-H characteristic assume H as input field, the inversion of the hysteresis operator at each step is required. The alternative approach is to assume B as input field, by using an approximate version of the Preisach hysteresis operator as constitutive relation in a finite element eddy current model. This approach is quite new and sensibly reduces the computational effort, since it avoids the inversion of the hysteresis operator at each time step. The numerical results are provided and compared to experimental data on a commercial Terfenol-D actuator