Controlled high power actuation utilising Terfenol-D

Abstract A high power non-resonant actuator based on the rare earth-iron magnetostrictive compound Terfenol-D has been constructed and its performance evaluated. Two types of spring loading have been applied with different compliancies. Under DC operation the less compliant spring produced limited displacement with large forces (120 μm @ 15 kN), whilst the more compliant load permitted larger displacements and smaller forces (550 μm @ 3 kN). Calculation of the work done in the latter case indicates an internal stress level in the Terfenol-D of approximately 6.4 MPa. For AC operation sinusoidal peak to peak currents of 28 amps generate a nett force of approximately 9 kN, over and above any applied prestress, which decreases by 10% at frequencies up to 400 Hz. Higher frequency components only appear at very high drive levels.