Constitutive Equations of a Shape Memory Alloy under Complex Loading Conditions

Author(s):  
MASATAKA TOKUDA
Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1687 ◽  
Author(s):  
A. B. M. Rezaul Islam ◽  
Ernur Karadoğan

A shape memory alloy (SMA) can remember its original shape and recover from strain due to loading once it is exposed to heat (shape memory effect). SMAs also exhibit elastic response to applied stress above the characteristic temperature at which transformation to austenite is completed (pseudoelasticity or superelasticity). Shape memory effect and pseudoelasticity of SMAs have been addressed by several microscopic thermodynamic and macroscopic phenomenological models using different modeling approaches. The Tanaka and Liang-Rogers models are two of the most widely used macroscopic phenomenological constitutive models for describing SMA behavior. In this paper, we performed sensitivity and uncertainty analysis using Sobol and extended Fourier Amplitude Sensitivity Testing (eFAST) methods for the Tanaka and Liang-Rogers models at different operating temperatures and loading conditions. The stress-dependent and average sensitivity indices have been analyzed and are presented for determining the most influential parameters for these models. The results show that variability is primarily caused by a change in operating temperature and loading conditions. Both models appear to be influenced by the uncertainty in elastic modulus of the material significantly. The analyses presented in this paper aim to provide a better insight for designing applications using SMAs by increasing the understanding of these models’ sensitivity to the input parameters and the cause of output variability due to uncertainty in the same input parameters.


2008 ◽  
Vol 59 ◽  
pp. 129-134
Author(s):  
Yuji Takeda ◽  
Takaei Yamamoto ◽  
M. Uegaki ◽  
Hiroki Cho ◽  
Toshio Sakuma ◽  
...  

This paper describes the transformation and deformation behavior and its constitutive equation for Ti-41.7Ni-8.5Cu (at%) shape memory alloy. Plastic deformation after pre-deformation is investigated using the volume fraction of slip-deformed martensite. New kinetics and constitutive equations are proposed for the reverse transformation process. The material constants in the proposed equationa are determined from the results of tensile and heating/cooling tests of Ti-41.7Ni-8.5Cu (at%) shape memory alloy. The calculated results describe well the deformation and transformation behavior affected by pre-strain.


2007 ◽  
Vol 2007.1 (0) ◽  
pp. 143-144 ◽  
Author(s):  
Tadashi INABA ◽  
Masataka TOKUDA ◽  
Atsuo HAYASHI ◽  
Noriyuki UEDA ◽  
Kazuhiro KITAMURA

2004 ◽  
Vol 177-178 ◽  
pp. 512-517 ◽  
Author(s):  
Wangyang Ni ◽  
Yang-Tse Cheng ◽  
David S Grummon

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