<title>Deformation behavior of shape memory alloy under complex loading conditions (modeling and constitutive relations)</title>

Owing to geometrical non-uniformity, geometrically graded shape memory alloy (SMA) structures by design have the ability to exhibit different and novel thermal and mechanical behaviors compared to geometrically uniform conventional SMAs. This paper reports a study of the pseudoelastic behavior of geometrically graded NiTi plates. This geometrical gradient creates partial stress gradient over stress-induced martensitic transformation, providing enlarged stress controlling interval for shape memory actuation. Finite element modeling framework has been established to predict the deformation behavior of such structures in tensile loading cycles, which was validated by experiments. The modeling results show that the transformation mostly propagates along the gradient direction as the loading level increases.

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Constitutive Equation for the Hot Deformation Behavior of TiNiNb Shape Memory Alloy

The Physics of Metals and Metallography ◽

10.1134/s0031918x19040082 ◽

2019 ◽

Vol 120 (4) ◽

pp. 394-401

Author(s):

Liu Junwei ◽

Lu Shiqiang ◽

Yao Qi ◽

Zhao Zhigang

Keyword(s):

Constitutive Equation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Hot Deformation ◽

Deformation Behavior ◽

Hot Deformation Behavior

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Sensitivity and Uncertainty Analysis of One-Dimensional Tanaka and Liang-Rogers Shape Memory Alloy Constitutive Models

Materials ◽

10.3390/ma12101687 ◽

2019 ◽

Vol 12 (10) ◽

pp. 1687 ◽

Cited By ~ 5

Author(s):

A. B. M. Rezaul Islam ◽

Ernur Karadoğan

Keyword(s):

Shape Memory Alloy ◽

Uncertainty Analysis ◽

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Constitutive Models ◽

Loading Conditions ◽

Input Parameters ◽

Stress Dependent ◽

Sensitivity And Uncertainty Analysis

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.

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Influence of matrix systems on the deformation behavior of adaptive fiber-reinforced plastics

Journal of Industrial Textiles ◽

10.1177/1528083720927010 ◽

2020 ◽

pp. 152808372092701

Author(s):

Moniruddoza Ashir ◽

Chokri Cherif

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Deformation Behavior ◽

Matrix Material ◽

Mixing Ratio ◽

Fiber Reinforced ◽

Reinforced Plastics ◽

Bending Modulus ◽

Hybrid Yarn ◽

Fiber Reinforced Plastics

Adaptive structures contain actuators that enable the controlled modification of system states and characteristics. Furthermore, their geometric configuration as well as physical properties can be varied purposefully. The geometric configuration of adaptive fiber-reinforced plastics can be changed by varying the bending modulus of the matrix material. Hence, this research work presents the influence of thermosetting matrix material with different bending moduli on the deformation behavior of adaptive fiber-reinforced plastics. Firstly, shape memory alloys were converted into shape memory alloy hybrid yarn in order to realize this goal. Subsequently, shape memory alloy hybrid yarn was textile-technically integrated into reinforcing fabrics by means of weaving technology. The bending modulus of the thermosetting matrix material was changed by mixing modifier into it. The Seemann Corporation Resin Infusion Molding Process was used for infusion. Later, the deformation behavior of adaptive fiber-reinforced plastics was characterized. Results revealed that the maximum deformations of adaptive fiber-reinforced plastics with resin and modifier at a mixing ratio of 9:1 and 8:2 were increased to 34% and 63%, respectively, compared to adaptive fiber-reinforced plastics infiltrated by the reference resin. The maximum deformation speed during heating and cooling of adaptive fiber-reinforced plastic with the mixing ratio of resin and modifier at a value of 8:2 were 41.17 mm/s and 26.89 mm/s, respectively.

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