Fatigue of Shape Memory Alloys with Emphasis On Additively-Manufactured NiTi Components

Abstract

Shape memory alloys (SMAs) are often used in applications involving time-varying loads. Under such conditions, fatigue leading to possible fracture is a paramount cause of failure, which has been extensively investigated since the 1960s. The present work reviews developments in this field with emphasis on recent results related to additively-manufactured SMAs. Multiple factors influencing structural and functional degradation in presence of cyclic loading are considered, including microstructural and surface features, thermal loading history and heat treatment. For completeness, select modelling approaches proposed in the literature to predict SMA fatigue are briefly overviewed and a discussion is provided on the statistical relevance and uncertainty of published data. Conclusions are then formulated to guide subsequent research.