STRENGTH AND MAGNETOSTRICTION CHARACTERIS TICS OF GIANT MAGNETOSTRICTIVE MATERIALS

Giant magnetostrictive materials are said to be capable of producing l arge forces and high power. When we actually attempted to design a hea vy load actuator using a giant magnetostrictive material, we soon beco me aware that the basic data required for design work is not enough. T his report presents the results of a study conducted in view of this s ituation, with the aim of ascertaining the strength and the magnetostr ictive characteristics of the giant magnetostrictive material. Static compression tests showed that the material has a strength of around 88 0 MPa. Compression fatigue tests showed that the material is able to w ithstand not less than 10(6) repeated loadings if the compression stre ss is kept at 500 MPa or less. Bending tests showed that the material has a strength of only about 40 MPa. An analysis of the chipping pheno menon along the edge of the compression surface of a rod-shaped materi al revealed that if the compression surface is flat, the stress at the edge of the surface becomes about twice than that at the center of th e material. The material exhibits magnetostriction even under stresses exceeding 100 MPa. The magnetostriction characteristics showed very l ittle hysterisis as a function of magnetic flux measured by a search c oil wound around the material.