Electrical tuning of magnetostrictive applications: Equivalent electromechanical circuit analysis

Electromechanical equivalent circuit models provide an efficient tool for analysis of power flow across multiple physical domains. This work applies this approach to analyze the dynamic behavior of magnetostrictive material-based devices. Here, the unimorph system consists of a magnetostrictive galfenol (Fe-Ga alloy) layer bonded to a non-magnetic flexible metal layer, a pick-up coil wound around the bimetallic strip, and an electrical load. Permanent magnets at both ends of the unimorph provide a magnetic bias. The electrical load, consisting of a resistance and capacitance, is connected to the pick-up coil, such that vibration in the magnetostrictive alloy layer generates electrical energy. From a system point of view, a transformation of the electrical and magnetic elements into the mechanical domain reveals a vibration absorption core structure of the electromechanical system with the appropriate applied electrical load. Experimental results from two different devices are presented and their dynamic behaviors are compared with simulations for purposes of adjustable damping and tunable energy harvesting. Because of the very good agreement between simulations and measurements, the presented network model can be used to predict the performance of magnetostrictive sensors, actuators, energy harvesters, and dampers with a similar structure.