Quality factor, static and dynamic responses of miniature galfenol actuator at wide range of temperature

Abstract

In this research, galfenol (iron-gallium alloy) is exploited to make a miniature actuator. The relationship between displacement and the applied current is measured. Furthermore, the dynamic behaviors of the actuator in wide range of temperature from cryogenic environment (77 K) to room temperature (RT) are investigated numerically and experimentally. Although, the length of galfenol bar is 10 mm and the maximum strain of annealed galfenol bar is 200 ppm, the large displacements of 37 and 25 μm are achievable at RT and 77 K, respectively when the coil is energized by ±1 A. The natural frequency of this actuator at RT and 77K is 1015 and 1075 Hz, respectively. Furthermore, modal analysis predicts the natural frequency of the actuator by maximum 9% error. Low hysteresis behavior makes this actuator suitable for positioning at both, RT and 77 K. It is also found that the low quality factor of actuator at RT is related to Joule heat dissipation. Key words: Galfenol (iron-gallium alloy), miniature actuator, cryogenic environment, quality factor, modal analysis.