A Multi-mechanism Model Describing Reorientation and Reorientation-Induced Plasticity of NiTi Shape Memory Alloy

• Published in: Acta mechanica solida Sinica 2018-08, Vol.31 (4), p.445-458
• Main Authors: Xu, Xiang, Xu, Bo, Jiang, Han M., Kang, Guo-zheng, Kan, Qian-hua
• Format: Article
• Language: English
• Subjects: Classical Mechanics; Engineering; Surfaces and Interfaces; Theoretical and Applied Mechanics; Thin Films
• ISSN: 0894-9166; 1860-2134
• DOI: 10.1007/s10338-018-0023-9

The recovery force or recovery strain is an important indicator of NiTi-based shape memory alloy devices. However, the restoring force or recoverable strain is partially restrained due to an interaction between reorientation and reorientation-induced plasticity. Therefore, a macroscopic multi-mechanism constitutive model was constructed to describe the degeneration of shape memory effect based on the phase diagram. The residual strain after cooling consists of reorientation strain and reorientation-induced plastic strain. An internal variable, i.e., the detwinned stress, and its evolution equation were introduced into the transformation kinetics equation to describe the nonlinear hardening characteristics induced by the combined reorientation and detwinning mechanisms during mechanical loading. Finally, the proposed model was numerically implemented to simulate the experiments of shape memory effect at different peak strains. Comparisons between the experimental and simulated results show that the proposed model can reasonably describe the degeneration of shape memory effect.