Degradation of Transformation Stress in a Bicrystal Cu-Al-Mn Shape-Memory Alloy Using Full-Field Stress and Strain Measurements

2021 ◽  
Author(s):  
Tung-Huan Su ◽  
Nian-Hu Lu ◽  
Chih-Hsuan Chen ◽  
Chuin-Shan Chen
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Stress And Strain ◽  
Full Field ◽  
Strain Measurements ◽  
Field Stress ◽  
Transformation Stress

scholarly journals Deformation Behavior of a Shape Memory Alloy: Nitinol

2008 ◽  
Author(s):  
Samantha Daly ◽  
Kaushik Bhattacharya ◽  
Guruswami Ravichandran
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Rolling Texture ◽  
Image Correlation ◽  
Space Applications ◽  
Deformation And Failure ◽  
Full Field ◽  
New Information ◽  
Macro Scale ◽  
First Time

Nickel-Titanium, commonly referred to as Nitinol, is a shape-memory alloy with numerous applications due to its superelastic nature and its ability to revert to a previously defined shape when deformed and then heated past a set transformation temperature. While the crystallography and the overall phenomenology are reasonably well understood, much remains unknown about the deformation and failure mechanisms of these materials. These latter issues are becoming critically important as Nitinol is being increasingly used in medical devices and space applications. The talk will describe the investigation of the deformation and failure of Nitinol using an in-situ optical technique called Digital Image Correlation (DIC). With this technique, full-field quantitative maps of strain localization are obtained for the first time in thin sheets of Nitinol under tension. These experiments provide new information connecting previous observations on the micro- and macro-scale. They show that martensitic transformation initiates before the formation of localized bands, and that the strain inside the bands does not saturate when the bands nucleate. The effect of rolling texture, the validity of the widely used resolved stress transformation criterion, and the role of geometric defects are examined.

Effect of the Addition of Gd on Ni53Mn22Co6Ga19 High-Temperature Shape Memory Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 2095-2098
Author(s):  
Yun Qing Ma ◽  
Shui Yuan Yang ◽  
San Li Lai ◽  
Shi Wen Tian ◽  
Cui Ping Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Earth Element ◽  
Stress And Strain ◽  
Martensitic Transformation Temperature ◽  
Rich Phase ◽  
Shape Memory Properties

The rare earth element Gd is added to Ni53Mn22Co6Ga19 high-temperature shape memory alloy to refine the grain size and adjust the distribution of γ phase, and their microstructure, martensitic transformation behaviors, mechanical and shape memory properties were investigated. The results show that the grain size is obviously decreased and the γ phase tends to segregate at grain boundaries with increasing Gd content. Small amounts of Gd-rich phase were formed with 0.1 at.% Gd addition. The martensitic transformation temperature abruptly increases with 0.1 at.% Gd addition, then almost keeps constant with further increasing Gd content. The addition of 0.1 at.% Gd is proved to be beneficial to both tensile stress and strain before fracture, but negative to the shape-memory effect.

Use of digital speckle pattern correlation for strain measurements in a CuAlBe shape memory alloy

2009 ◽  
Vol 60 (8) ◽  
pp. 775-782 ◽  
Author(s):  
F.M. Sánchez-Arévalo ◽  
T. García-Fernández ◽  
G. Pulos ◽  
M. Villagrán-Muniz
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Speckle Pattern ◽  
Strain Measurements ◽  
Pattern Correlation ◽  
Digital Speckle

Transformation stress of shape memory alloy CuZnAl: Non-Schmid behavior

2018 ◽  
Vol 149 ◽  
pp. 220-234 ◽  
Author(s):  
S. Alkan ◽  
Y. Wu ◽  
A. Ojha ◽  
H. Sehitoglu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Transformation Stress

Mechanical Behavior of Super-Elastic Home-Made NiTi Shape Memory Alloy Bar in Tension

2013 ◽  
Vol 671-674 ◽  
pp. 1817-1820 ◽  
Author(s):  
Hai Jun Zhou ◽  
Hai Feng Liu ◽  
Hong Hong Huang
Keyword(s):  
Shape Memory Alloy ◽  
Mechanical Behavior ◽  
Shape Memory ◽  
Experimental Tests ◽  
Niti Shape Memory Alloy ◽  
Characteristic Parameters ◽  
Equivalent Damping ◽  
Application Potential ◽  
Transformation Stress ◽  
Strain Energy Loss

An experimental study on mechanical behavior of home-made super-elastic NiTi Shape Memory Alloy (SMA) bar subjected to tension was made. The SMA bar specimen was 8mm in gage diameter and 50mm in gage length. The experimental tests were carried out by applying repeated cyclic loads. The tested tension strain amplitudes were 1%-7% and material phase was austenite. The mechanical characteristic parameters, such as phase transformation stress, deformation module, residual strain, energy loss and equivalent damping were studied. The effects of strain amplitude, loading rate and loading cycles on these parameters were analyzed. The considerable super-elasticity and stable cyclic behaviors of home-made SMA bar during the test showed its great application potential in aseismic devices.

Numerical Investigations of Thermally Induced Transformation, Reorientation of Martensite Variants and Shape Memory Effect Using Constitutive Model for Accommodation of Transformation Strain

2011 ◽  
Vol 687 ◽  
pp. 510-518 ◽  
Author(s):  
Hiroki Cho ◽  
Akihiko Suzuki ◽  
Takaei Yamamoto ◽  
Yuji Takeda ◽  
Toshio Sakuma
Keyword(s):  
Constitutive Model ◽  
Shape Memory ◽  
Transformation Strain ◽  
Stress And Strain ◽  
Transformation Behavior ◽  
Thermally Induced ◽  
Numerical Investigations ◽  
Transformation Stress ◽  
Micro Structures ◽  
Transformation Systems

To confirm the constitutive model developed by the present authors, example calculations are conducted for the transformation behavior of shape memory alloys. The constitutive model describes the transformation behavior of the material by calculating the transformation stress and strain of transformation systems of micro structures in the material. In the calculating, the accommodation mechanism acting on microstructures of the material is also taken into consideration. Computational results by the constitutive model for these loading paths are revealed to be reasonable in comparing with experimental observations.

Sign in / Sign up

Export Citation Format

Share Document