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 ±1 , which realized the precise positioning by the Terfenol-D actuator.

Temperature compensation design and experiment for a giant magnetostrictive actuator

“…The phase change temperature control method has been recently introduced into GMA temperature control applications [20][21][22][23] . Liu 20 placed a phase change material between the drive coil and the magnetostrictive rod, which can absorb the heat generated by the coil and prevent this heat from being transferred to the magnetostrictive rod while absorbing the magnetostrictive rod itself due to eddy current heat generated by hysteresis loss.…”