Large Deformation Behavior of Non-circular Wire Helical Spring with the Fe-based Shape Memory Alloy

Abstract

A non-circular wire helical spring generally has a high spring constant and reduces the spring height at fully compressed condition, although the energy absorption decreases during deformation. For improving this energy absorption, we have applied Fe-Mn-Si based alloy （ FMS ） to the spring. FMS that is one of the shape memory alloys （ SMA ） have more reasonable and workable than any other type of the SMAs, e.g. Ti-Ni alloy. Its shape memory effect and super elasticity that are caused with the stress-induced γ（ Austenite ）⇔ ε martensitic transformation have been studied for. The cycled tensile tests are conducted on the springs made of FMS, S45C and SUS304. The load-displacement curve of FMS obtained by the cycled tensile test indicates a reversible large hysteresis loop. This is caused by deformation in two different processes of stress-induced martensitic transformation at loading, and reverse transformation at unloading. The non-circular wire helical spring of FMS is able to absorb more energy in early stage during large deformation than of S45C and SUS304.