Fully coupled simulation of magnetic shape memory alloys under elongating and contracting perpendicular magnetic fields

Abstract:
This paper shows the fully coupled simulation of magnetic shape memory alloys (MSMA) under perpendicular magnetic fields using idealized switching domains. Fields perpendicular to the deformation direction result in an elongation while fields alongside the MSM-element result in a contraction. Because of MSMA’s inherent twinning stress, this can be used to develop multistable push-pull-actuators. The proposed model incorporates generic pole shoes to capture their influence on the switching behavior. The performance is investigated for different twinning stress distributions. For mechanical excitation, the domain’s switching pattern closely follows the twinning stress distribution. For magnetic fields along the deformation direction, the domains start to contract from the end faces moving inward, while perpendicular fields result in a rather equally distributed elongation behaviour. An overall cycle of both field directions shows the full range of motion. Stopping the excitation at an intermediate level shows the multistable behaviour. Based on an upcoming test rig for perpendicular field excitations, optical investigations are performed to illustrate the switching behaviour and validate the modelling approach.