Numerical modelling of pseudoelastic behaviour of geometrically graded shape memory alloys. (April 2019)

• Record Type: Journal Article
• Authors: Shariat, Bashir S; Bakhtiari, Sam; Liu, Yinong
• Is Part Of: IOP conference series. Volume 522(2019)
• Publication Date: 2019-04
• Subjects: Materials science -- Periodicals; 620.1105
• DOI: 10.1088/1757-899X/522/1/012005
• Languages: English
• ISSNs: 1757-8981

Abstract

Abstract: This study presents numerical modelling based on finite element method for pseudoelastic behaviour of geometrically graded shape memory alloy structures made of near-equiatomic NiTi thin plates. Near-equiatomic NiTi alloy undergoes Lüders-type deformation via stress-induced martensitic transformation over a flat stress plateau with a practically nil stress window over the transformation strain, rendering it impossible for stress controlled actuation. To improve the controllability of a shape memory component in such applications, it is required to have a reasonably wide stress window for the stress-induced transformation in the alloy. One approach to achieving this goal is to design a geometrically graded structure to allow the component to undergo the transformation in different parts under different stress levels. This study investigates the deformation behaviour of geometrically graded NiTi structures with series and parallel design configurations with respect to the loading direction. It reveals that the transformation propagation is along the loading direction in a sample with the series design configuration, whereas it is perpendicular to the loading direction in a sample with the parallel design configuration.