Characterization and Modeling of Dynamic Sensing Behavior in Ferromagnetic Shape Memory Alloys

Abstract

This paper is focused on the characterization and modeling of a commercial Ni-Mn-Ga alloy for use as a dynamic deformation sensor. The flux density is experimentally determined as a function of cyclic strain loading at frequencies from 0.2 Hz to 160 Hz. With increasing frequency, the stress-strain response remains almost unchanged whereas the flux density-strain response shows increasing hysteresis. This behavior indicates that twin-variant reorientation occurs in concert with the mechanical loading, whereas the rotation of magnetization vectors occurs with a delay as the loading frequency increases. The increasing hysteresis in magnetization must be considered when utilizing the material in dynamic sensing applications. A modeling strategy is developed which incorporates magnetic diffusion and a linear constitutive equation.

Smart Materials and Structures: State of the Art and Applications

“…Major advantages of smart material actuators and sensors include high energy density, fast response, compact size, and fewer moving parts. Some disadvantages include limited strain outputs, limited blocking forces, high cost, and sensitivity to harsh environmental conditions [5].…”