Influence of Ultrasonic Shot Peening on Fatigue Life of TiNi Shape Memory Alloy Wire

Abstract

The shape memory alloy (SMA) is expected to be applied as intelligent materials since it shows the unique characteristics of the shape memory effect and superelasticity. In the growing number of TiNi SMA applications, these materials should fulfill high requirements of fatigue, corrosion and wear resistance. On the other hand, the application of SMA has some limitations, particularly in thermomechanical cyclic loading cases. In these cases, fatigue of SMA is one of the important properties in view of evaluating functional characteristics as SMA elements. The study on enhancement of the fatigue life for TiNi SMA by ultrasonic-shot peening (USP) has not been investigated till now. In particular, since impressions appear little by USP in the region of superelasticity, the influence of USP on the fatigue life is not clear. In this paper, we report and discuss the influence of USP shot media diameter d and coverage c on the bending fatigue life of TiNi SMA tape which shows superelasticity.