Precise Positioning of Terfenol-D Actuator by Eliminating the Heat Generated by Coil

Abstract

Large displacement, large generated stress and easy fabrication process lead to the large industrial use of the magnetostrictive materials. However, the thermal expansion restricts their application in precise positioning, which is about 12  and too much to be neglected. In this research, the cooling system was exploited in order to eliminate the joule heat generated by coils under the direct current and solve inaccuracy problem. The investigation consists of two parts; first was design and fabricating the actuator of Terfenol-D with length of 30mm which offers 10  displacement under the DC current of 1A, and second was the cooling system consisting of the thermoelectric cooler, heat sink and control circuit to inhibit the Terfenol-D temperature to be increased. Without the cooling system, as the time was going on and the Terfenol-D was warming up, after about two hours the displacement reached to 68  which deteriorated the accuracy of positioning significantly. By applying the cooling system, the displacement was maintained in 10  with the tolerance of , which realized the precise positioning by the Terfenol-D actuator.