Ferromagnetic shape memory alloy (FSMA) composites composed of a ferromagnetic material and a shape memory alloy (SMA) are key material system for fast-responsive and compact actuators. The function of ferromagnetic material is to induce magnetic force which is then used to induce the stress in the SMA, resulting in the stress-induced martensite transformation (SIM), i.e. change in the Young's modulus, stiff (austenite) to soft (martensite). This SIM induced phase change causes larger deformation in the SMA, which is often termed as "superelastic". This sequence of actions is termed as "hybrid mechanism", which we found the most effective one in making use of FSMA composite with applied magnetic flux gradient.This talk discusses a simple model by which the stress and strain field in the FSMA composites subjected to bending and torsion loading are computed with aim of identifying the optimum geometry of FSMA composites. The results of the present analytical study are utilized to design of torque actuator (bending of FSMA composite plate) and spring actuator (torsion of helical FSMA composite spring).
展开▼
