SCALING-UP ISSUES WITH A MAGNETOSTRICTIVE HYDRAULIC PUMP

摘要

A hybrid magnetostrictive hydraulic actuator capable of applying a prescribed pre-stress on the magnetostrictive driver was designed and built. Performance of the pump was analyzed using a 2" long and a 4" long magnetostrictive Terfenol-D rod to address scaling up issues. The peak in output velocity, under no external loading, of both pumps occurred around 3.5in/sec. The 4" pump had a larger frequency bandwidth while the 2" pump exhibited a large drop in output velocity at much lower driving frequencies. The load line of the 4" pump was slightly more shifted to the right compared to the 2 " pump, indicating higher blocked force and free velocity. The relatively low increase in performance moving from the 2" to the 4" pump was attributed to lower stiffness of the longer rod and the larger impedance of the 4" long solenoid that caused amplifier saturation and resulted in lower saturation magnetostriction from the Terfenol-D driver.