Influence of Small-Strain and Large-Strain Methods on Mechanical Behaviors in Shape Memory Alloys

2011 ◽  
Vol 328-330 ◽  
pp. 1556-1559
Author(s):  
Yun Zhang Wu ◽  
Yu Ping Zhu ◽  
Guan Suo Dui
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shear Deformation ◽  
Uniaxial Tension ◽  
Phenomenological Model ◽  
Large Strain ◽  
Small Strain ◽  
Thermodynamic Theory ◽  
Mechanical Behaviors ◽  
The Difference

Based on thermodynamic theory, a phenomenological model of shape memory alloy is provided. Simulations under different loading illustrate the influence of large-strain deformation and small-strain deformation on the characteristics of the model. The results indicate that the difference between the two methods is small under uniaxial tension case, while the influence is very large under shear deformation case.

The Research of the Difference between Small-Strain and Large-Strain Formulations for Shape Memory Alloys

2012 ◽  
Vol 229-231 ◽  
pp. 3-9
Author(s):  
Jie Yao ◽  
Young Hong Zhu ◽  
Yun Zhang Wu
Keyword(s):  
Phase Transformation ◽  
Constitutive Model ◽  
Shape Memory ◽  
Uniaxial Tension ◽  
Driving Force ◽  
Large Strain ◽  
Small Deformation ◽  
Small Strain ◽  
Proportional Loading ◽  
The Difference

Based on thermodynamics and phase transformation driving force, we apply a SMA constitutive model to analyze the large and small deformation of SMA materials. Simulations under different loading, uniaxial tension and shear conditions, illustrate the characteristics of the model in large strain deformation and small strain deformation. The results indicate that the difference between the two methods is small under the uniaxial tension case, while the large deformation and the small deformation results are very different under shear deformation case. It lays a foundation for the further studies of the constitutive model of SMA, especially in the multiaxial non-proportional loading aspects.

The Further Exploration of Applying Small-Strain and Large-Strain Formulations to SMA

2012 ◽  
Vol 529 ◽  
pp. 228-235
Author(s):  
Jie Yao ◽  
Yong Hong Zhu
Keyword(s):  
Phase Transformation ◽  
Constitutive Model ◽  
Uniaxial Tension ◽  
Driving Force ◽  
Research Team ◽  
Large Strain ◽  
Small Deformation ◽  
Small Strain ◽  
Proportional Loading ◽  
The Difference

Recently, our research team has been considering to applying shape memory alloys (SMA) constitutive model to analyze the large and small deformation about the SMA materials because of the thermo-dynamics and phase transformation driving force. Accordingly, our team use simulations method to illustrate the characteristics of the model in large strain deformation and small strain deformation when different loading, uniaxial tension, and shear conditions involve in the situations. Furthermore, the simulation result unveils that the difference is nuance concerning the two method based on the uniaxial tension case, while the large deformation and the small deformation results have huge difference based on shear deformation case. This research gives the way to the further research about the constitutive model of SMA, especially in the multitiaxial non-proportional loading aspects.

Complex transformation field created by geometrical gradient design of NiTi shape memory alloy

2017 ◽  
Vol 10 (01) ◽  
pp. 1740011 ◽  
Author(s):  
Reza Bakhtiari ◽  
Bashir S. Shariat ◽  
Fakhrodin Motazedian ◽  
Zhigang Wu ◽  
Junsong Zhang ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Deformation Behavior ◽  
Stress Gradient ◽  
Tensile Loading ◽  
Niti Shape Memory Alloy ◽  
Mechanical Behaviors ◽  
Modeling Framework ◽  
Complex Transformation ◽  
Pseudoelastic Behavior

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.

Microstructural and Fractographic Analysis of CuAlNi Shape Memory Alloy before and after Heat Treatment

2020 ◽  
Vol 405 ◽  
pp. 100-106
Author(s):  
Ivana Ivanić ◽  
Mirko Gojić ◽  
Stjepan Kožuh ◽  
Borut Kosec
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Fracture Surface ◽  
Shape Memory ◽  
Fractographic Analysis ◽  
Before And After ◽  
Different Temperatures ◽  
The Difference ◽  
Type Of Fracture ◽  
Scanning Electron

The paper presents comparison of microstructure and fracture surface morphology of the CuAlNi shape memory alloy (SMA) after different heat treatment procedures. The investigation was performed on samples in as-cast state and heat treated states (solution annealing at temperatures of 850 °C / 60’ / H2O and 920 °C / 60’ / H2O along with tempering at two different temperature 150 °C / 60’ / H2O and 300 °C / 60’ / H2O). The microstructure of the samples was examined by optical (OM) and scanning electron microscope (SEM) equipped with device for EDS analysis. The obtained fracture surfaces were examined by SEM. Optical and scanning electron microscopy showed martensitic microstructure in all investigated samples. However, the fractographic analysis of samples after tensile testing reveals significant changes in fracture mechanism. In both solution annealed states the results shows transgranular type of fracture, but after tempering at two different temperatures the difference is obvious. After tempering at 150 °C, along with transgranular type of fracture appear some areas with intergranular type of fracture. After tempering at 300 °C, fracture surface reveals completely intergranular type of fracture.

Simulation on Uniaxial-Tension Behavior of NiTi Shape Memory Alloy Films

2009 ◽  
Vol 79-82 ◽  
pp. 1209-1212
Author(s):  
Shuang Shuang Sun ◽  
Jing Dong
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Uniaxial Tension ◽  
Theoretical Foundation ◽  
Quantitative Description ◽  
Experimental Results ◽  
Niti Shape Memory Alloy ◽  
Alloy Films ◽  
Actuation Mechanism ◽  
Micro Actuators

Based on experimental results reported in the reference, Liang-Rogers’ constitutive model for SMA is used to simulate the stress-strain curves of NiTi shape memory alloy films under uniaxial tension with isothermal conditions. The effects of film compositions and temperature on the tensile behavior of NiTi shape memory alloy films are discussed. By comparing the simulation results with the experimental results, it is found that the simulation curves agree basically with the experimental curves except that the phase-transformation regions are wider in the simulation curves. This demonstrates that the Liang-Rogers’ model can be used to predict the thermomechanical behavior of shape memory alloy films roughly. This study provides some theoretical foundation for the quantitative description and prediction of the actuation mechanism when shape memory alloy films are used as micro-actuators.

A Phenomenological Model for Superelastic Shape Memory Alloy Helical Springs

2015 ◽  
Vol 18 (9) ◽  
pp. 1345-1354 ◽  
Author(s):  
Bin Huang ◽  
Wuchuan Pu ◽  
Haiyang Zhang ◽  
Han Wang ◽  
Gangbing Song
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Phenomenological Model ◽  
Helical Springs

Study on Crack Tip Field of Shape Memory Alloy Board under Torsion Load

2013 ◽  
Vol 663 ◽  
pp. 397-402
Author(s):  
Bo Zhou ◽  
Tai Yue Yin ◽  
Shi Feng Xue
Keyword(s):  
Phase Transition ◽  
Field Equation ◽  
Shape Memory Alloy ◽  
Stress Field ◽  
Shape Memory ◽  
Crack Tip ◽  
Martensitic Phase ◽  
Mechanical Behaviors ◽  
Crack Tip Field ◽  
Martensitic Phase Transition

This paper focuses on the thermo-mechanical behaviors of the shape memory alloy board with a crack and under the torsion load. A stress field equation from mechanics of elasticity is used to describe the stress distribution around the crack tip in the shape memory alloy board. A martensitic phase transition equation is supposed to predict the martensitic phase transition behaviors of the field near the crack tip in the shape memory alloy board. The martensitic phase transition zones near the crack tip in the shape memory alloy board under the torsion load are numerically described based on the stress field equation and martensitic phase transition equation at various temperatures. Results show that the stress field equation and martensitic phase transition equation can predict the thermo-mechanical behaviors of the shape memory alloy board with a crack and under the torsion load effectively.

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