Effect of Axial Grooves on Eddy Current Loss within Giant Magnetostrictive Material (GMM) Rod

Abstract

The non-linear relationship between the magnetic field intensity and magnetostrictive strain which is caused by the thermal expansion produced by the eddy current loss in the GMM rod, will affect the precision and stability of GMM actuator. This paper tries to reduce the eddy current loss in the GMM rod to improve the performance of magnetostrictive actuator by machining radial grooves in the surface of the rod. The numerical results show that the axial grooves can be effective in reducing thermal power loss. The groove size and number are both optimized by numerical method. The results show that the groove depth and number has great impact on the unit volume eddy current loss while the groove width has little or no impact. The test of the magnetostrictive strain shows that the linearity of the GMM rod with grooves is significantly improved. The radial grooves in the GMM surface can reduce the eddy current loss and improve the performance of GMM actuator.