Effect of stress redistribution during thermal actuation of shape memory alloys in notched cylindrical bars

Abstract

Shape memory alloys present a unique ability to undergo a solid-to-solid, diffusionless, reversible phase transformation. The forward phase transformation is commonly associated with transforming from the austenitic phase to the martensitic phase, while the reverse transformation is defined by going from the martensitic phase to the austenitic phase. In thermal actuation loading paths, forward transformation is generally associated with cooling, while reverse transformation is commonly associated with heating. In this article, however, it is shown that reverse transformation may occur during cooling of notched cylindrical shape memory alloy bars. The reversal in phase transformation is associated with the redistribution of stress in the shape memory alloy due to the phase transformation.

Crack Growth Behavior in NiTi Shape Memory Alloys Under Mode-I Isothermal Loading: Effect of Stress State

“…SMAs have found applica-tions in aerospace, automotive, biomedical, oil and gas exploration, and energy storage industries owing to their superior performance when compared to conventional materials [1]. Studying the failure mechanisms of SMAs has been of recent interest [2][3][4][5]. Understanding the fracture response and crack growth behavior of SMAs is thus crucial for robust and reliable design of geometrically large SMA components and their successful integration into smart structures.…”