Structural vibration control using linear magnetostrictive actuators

Terfenol-D is one of several magnetostrictive materials with the property of converting energy into mechanical motion, and vice versa. We designed and fabricated a linear magnetostrictive actuator (MSA) using Terfenol-D as a control device. In order to grasp the dynamic characteristics of the actuator, a series of experimental and numerical tests were performed. Induced-strain actuation displacements of the actuator measured by the test and predicted by magnetic analysis agreed well, and blocked forces, according to the input currents, were estimated from the testing results. A modeling method representing the exerting force of the actuator was confirmed through some testing results. We also explored the effectiveness of the linear MSA as a structural control device. A series of numerical and experimental tests was carried out with a simple aluminum beam supported only at each end by such an actuator. After the equation of motion of the controlled system was obtained by the finite element method, a model reduction was performed to reduce the number of degrees of freedom. A linear quadratic feedback controller was implemented on a real-time digital control system to dampen the first four elastic modes of the beam. Through some tests, we confirmed the capability of the actuator for controlling beam-like structures.