Investigation into the shift of electromechanical conversion efficiency with temperature for Giant magnetostriction ultrasonic processing system

Abstract

In this paper, a high-power rotary ultrasonic machining system was proposed using a novel magnetostrictive material with giant magnetostriction (over 1000 ppm), high energy density, and fast response speed, namely Giant magnetostriction ultrasonic processing system (GMUPS). By applying the equivalent circuit of the GMUPS, the electromechanical conversion efficiency model was presented, and the effects of temperature rise on the electromechanical conversion efficiency and optimal compensation parameter were studied. The impedance of the GMUPS using various compensation capacitances were measured to determine the optimal compensation capacitances under three kinds of steady temperatures, and the variations in vibration amplitude output of the GMUPS were tested using a specific excitation voltage to validate the results of impedance analysis. These results show that the vibration amplitude was maximized by using optimal compensation, and the optimal compensation capacitance was consistent at whole temperatures. In addition, the relation between electromechanical conversion efficiency and temperature was established by measuring the impedance circles of the GMUPS with optimal compensation under various temperatures. As demonstrated by comparison with the results of vibration test, the electromechanical conversion efficiency of the GMUPS was found to decrease with increasing temperature, while the power output by the power supply increases using a specific excitation voltage. As a result, the vibration-amplitude-current sensitivity firstly increases and then decreases rapidly with temperature rise. It is of great practical value for controlling and adjusting the vibration amplitude for the GMUPS.