Abstract: Giant magnetostrictive material Terfenol-D is widely used in dynamic applications such as ultrasonic transducers and active vibration control structures, with the advantages of large magnetostriction, quick time response and high energy density. Magnetic materials under alternating magnetic field generate eddy current losses. The higher of working frequency, the larger eddy current losses are generated, which causes the low output power efficiency with these devices. By analyzing the key factors of eddy current cut-off frequency and penetration depth that both affect eddy current losses, the methods to effectively restrain eddy current losses include decreasing conductivity of magnetostrictive materials and using laminated structure. The model of eddy current losses is established based on Maxwell’s equations, and experiments are carried out to compare the effect of eddy current losses on both impedance curve and vibration velocity amplitude between laminated and monolithic magnetostrictive structures. Result shows the laminated type can reduce the eddy current losses drastically and it also matches eddy current loss model built above.

Key words: Cut-off frequency, Eddy current losses, Giant magnetostrictive materials, Laminated structure, Maxwell’s equations