Deformation Analysis for Coil Spring of Ti-Ni Shape Memory Alloy in the Superelastic Regime

Abstract

FEM analysis results for coil spring specimens of Ti-Ni shape memory alloys were compared with experimental results in the superelastic regime. The input data for FEM analyses were obtained from wire specimens of the same material as that of coil spring specimens. The calculated results did not agree with experimental results. Two possible causes were pointed out on the disagreement between calculated and experimental results. One is the insufficient treatment in the constitutive relations under multiaxial stress states. The other is the discrepancy in the work rates between coil spring specimens and wire specimens. Some examinations were performed on these points.