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Journal of Metallurgy
Volume 2011 (2011), Article ID 563413, 14 pages
http://dx.doi.org/10.1155/2011/563413
Research Article

One-Dimensional Constitutive Model of Shape Memory Alloy with an Empirical Kinetics Equation

1State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China
2China Three Gorges Corporation, Yichang, Hubei Province 443133, China
3Department of Transportation of Henan Province, Zhengzhou 450052, China

Received 8 November 2010; Accepted 11 January 2011

Academic Editor: D. H. Ping

Copyright © 2011 Lei Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Characteristics of NiTi shape memory alloy (SMA) and its constitutive model with an empirical kinetics equation were investigated in this paper. Firstly, the transformation characters of the NiTi SMA were obtained through a differential scanning calorimetry (DSC) analysis technology, and the properties during incomplete and discontinuous transformation process and the effects of plastic deformation on the transformation were studied. The uniaxial tension, SME, and constrained recovery process of NiTi SMA were examined through an improved 10KN universal material testing machine. Experimental results indicated that the phase transformation characters and the mechanical properties could be affected by the loading process considerably, and the plastic deformation should be taken into account. To simulate the characteristics of NiTi SMA more effectively, a one-dimensional constitutive model derived from the internal variable approach with the consideration of the plastic deformation was constructed based on the DSC and the uniaxial tension experimental results, and a new simple empirical kinetics equation was presented, with the transformation temperature parameters redefined according to the DSC experiment evidence. Comparison between the numerical and experimental results indicated that this constitutive model could simulate the phase transformation characters, the uniaxial tension, SME, and the constrained recovery behavior of NiTi SMA well.