Analysis of Magnetic Field Characteristics of a Giant Magnetostrictive Actuator with a Semi-Closed Magnetic Circuit

The internal magnetic field characteristics of giant magnetostrictive actuators have an important influence on their output performance. Aiming at the deficiency of current scholars' research, based on the electromagnetic theory and finite element method, this paper analyzes the magnetic field intensity on a giant magnetostrictive cylinder by using COMSOL Multiphysics software. Considering the inhomogeneity of magnetic field intensity along the radial direction of giant magnetostrictive cylinders, a new averaging method is introduced to calculate the magnetic field intensity in the axial section of the cylinder. The influence of the magnetic permeability of the displacement conversion mechanism (shell) and the size of the air gap inside the device on the magnetic field intensity of the giant magnetostrictive cylinder are analyzed. The prototype of the actuator is manufactured, and the correctness and accuracy of the simulation data are verified by experiments. In order to make the magnetic field on the cylinder strong and uniform, the displacement conversion mechanism and the shell should be made of low permeability and high permeability materials, respectively, and the air gap size should be reduced as much as possible under the condition of meeting the size requirement of the actuator pre-tightening force applying device.