Experimental Study on the Recovery Stress of Shape Memory Alloy Strands and Wire

Abstract

Considering the advantages of steel strands in mechanical properties, a new form of shape memory alloy (SMA) wire, SMA strands, is designed in this study. To compare the recovery properties of martensitic SMA strands and SMA wire, the recovery stress of which with different prestrains were tested by using a material testing machine with a temperature-controlled cabinet. In this experiment, the SMA strands and the SMA wire have the same composition and the same cross-sectional area. The experimental results show that the maximum recovery stresses of the SMA strands with different prestrain are almost the same, which illustrates that the prestrain has no much effect on the maximum recovery stress of the SMA strands. Moreover, the recovery stress curve in heating stage does not coincide with that in cooling stage. Furthermore, the residual recovery stress of the SMA strands in cooling stage is also smaller than that of the SMA wire. This demonstrates the SMA strands can recovery initial state better.