A preliminary look at how geometry influences the magneto-mechanical behavior of magnetic shape memory alloys

Abstract

Magnetic shape memory alloys (MSMAs) are new materials that emerged in the late 1990s. The magnetic shape memory effect is a result of the rearrangement of martensitic variants under the influence of magnetic fields. Due to their newness there is limited understanding of the mechanical behavior of MSMAs. However, it is know that MSMAs are able to produce relatively large strains as compared to piezoelectric materials or conventional shape memory alloys (SMAs). In addition, MSMAs have a lower time constant than conventional SMAs, since their actuation frequency is not limited by heat transfer. These features make MSMAs attractive for a number of applications, but they must be thoroughly understood before they can be used. This work includes an experimental investigation on MSMAs where the material is loaded and unloaded in uniaxial compression in the presence of a perpendicular constant magnetic field. The modeling of the magneto-mechanical behavior of MSMAs under such loading is also presented. The experiments are performed on prismatic specimens with square and rectangular base. The experimental data is simulated using the Kiefer and Lagoudas model and a polynomial hardening rule calibrated on data from Couch et al.