Study on 3D Internal Magnetic Field Distribution and Dynamic Mechanics of a Giant Magnetostrictive Actuator

Abstract

The three-dimensional (3D) coupled magneto-elastic dynamic model of a giant magnetostrictive actuator (GMA) was built based on Maxwell’s equations, elasticity, and vibration theories. The general analytical expressions for the 3D internal magnetic field distribution of GMA were derived, and the corresponding analytical solutions were obtained. This analytical model is able to predict the internal magnetic field distribution and the output displacement of GMA system with different physical parameters under external excitations. The dynamic behaviors, such as the amplitude vs. frequency responses and the time domain waveforms of the GMA, were also studied. Analytical solutions showed that the internal magnetic field has a prominent end effect along the axial direction of a giant magnetostrictive material (GMM) rod, whereas a minimal skin effect along its radial direction, which are matched very well with the FEM results. The amplitude-frequency relationship exhibited prominent resonance and anti-resonance characteristic, which is a typical hysteresis feature of the GMA system. In order to testify the validity of the model prediction, a GMA testing system was also established. Excellent agreement was found between the experiment measurements and model predictions in the range of our research (frequency is lower than 300 Hz). The analytical results of the present study have potential applications in the fields of active vibration control and other precision machining of the GMA system.