Effects of thermal stress on magnetostrictive properties of polymer-bonded Terfenol-D composites

For polymer-bonded Terfenol-D composites, the difference between cure temperature and application temperature and the difference in thermal expansion coefficient between the magnetostrictive panicle and polymer matrix result in thermal stress in particles, which will influence the magnetostrictive properties of the smart composites. In this paper, the value of the thermal stress and the factors which influence it are analyzed theoretically, which indicates that the thermal stress increases with the increase of the temperature difference and the decrease of the particle volume fraction. Then at various cure temperatures and a constant orientation field, 20% and 50% volume fraction epoxy-bonded Terfenol-D composites were fabricated and tested at room Temperature. The experimental results indicate that both the dynamic and static magnetostrictive properties of the composites increase with the increasing cure temperature because of the increase of the thermal stress. But they do not decrease with the increase of the particle volume fraction although the thermal stress decreases, because the positive effect of the increase of the function phase offsets or even exceeds the negative effect.