Design and characterization of a multi-stable magnetic shape memory alloy hybrid actuator

This paper describes the design and the characterization of a multi-stable hybrid actuator composed of a single magnetic shape memory alloy element and an electromagnetic actuator. The series arrangement of the active material and the electromagnetic actuator allows a new shape of hysteresis curve and a precise positioning can be obtained. The design of the different magnetic circuits has been done by analytic and numeric simulations in MatLab and FEMM 4.2. This study gives results of the elongation, the blocking force, and the holding force that can be obtained with such an actuator. Strokes up to 0.35 mm and a blocking force of 2.6 N have been measured for the hybrid actuator using a magnetic shape memory alloy with a cross section of 2.5 mm². Such an actuator can find application in precise positioning and medium frequency actuation systems. Nevertheless, there is much design space for improvements in terms of energy consumption, heat transfer, and overall cost of the device.