Full-field stress and strain measurements revealing energy dissipation characteristics in martensitic band of Cu-Al-Mn shape memory alloy

As a stimulus-sensitive material, the difference in composition, fabrication process, and influencing factors will have a great effect on the mechanical properties of a superelastic Ni-Ti shape memory alloy (SMA) wire, so the seismic performance of the self-centering steel brace with SMA wires may not be accurately obtained. In this paper, the cyclic tensile tests of a kind of SMA wire with a 1 mm diameter and special element composition were tested under multi-working conditions, which were pretreated by first tensioning to the 0.06 strain amplitude for 40 cycles, so the mechanical properties of the pretreated SMA wires can be simulated in detail. The accuracy of the numerical results with the improved model of Graesser’s theory was verified by a comparison to the experimental results. The experimental results show that the number of cycles has no significant effect on the mechanical properties of SMA wires after a certain number of cyclic tensile training. With the loading rate increasing, the pinch effect of the hysteresis curves will be enlarged, while the effective elastic modulus and slope of the transformation stresses in the process of loading and unloading are also increased, and the maximum energy dissipation capacity of the SMA wires appears at a loading rate of 0.675 mm/s. Moreover, with the initial strain increasing, the slope of the transformation stresses in the process of loading is increased, while the effective elastic modulus and slope of the transformation stresses in the process of unloading are decreased, and the maximum energy dissipation capacity appears at the initial strain of 0.0075. In addition, a good agreement between the test and numerical results is obtained by comparing with the hysteresis curves and energy dissipation values, so the numerical model is useful to predict the stress–strain relations at different stages. The test and numerical results will also provide a basis for the design of corresponding self-centering steel dampers.

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Numerical Modeling of Unreinforced Masonry Walls Strengthened with Fe-Based Shape Memory Alloy Strips

Materials ◽

10.3390/ma14112961 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2961

Author(s):

Moein Rezapour ◽

Mehdi Ghassemieh ◽

Masoud Motavalli ◽

Moslem Shahverdi

Keyword(s):

Energy Dissipation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Unreinforced Masonry ◽

Masonry Wall ◽

Masonry Walls ◽

Vertical Strip ◽

Maximum Resistance ◽

The Cross ◽

Post Tensioning

This study presents a new way to improve masonry wall behavior. Masonry structures comprise a significant part of the world’s structures. These structures are very vulnerable to earthquakes, and their performances need to be improved. One way to enhance the performances of such types of structures is the use of post-tensioning reinforcements. In the current study, the effects of shape memory alloy as post-tensioning reinforcements on originally unreinforced masonry walls were investigated using finite element simulations in Abaqus. The developed models were validated based on experimental results in the literature. Iron-based shape memory alloy strips were installed on masonry walls by three different configurations, namely in cross or vertical forms. Seven macroscopic masonry walls were modeled in Abaqus software and were subjected to cyclic loading protocol. Parameters such as stiffness, strength, durability, and energy dissipation of these models were then compared. According to the results, the Fe-based strips increased the strength, stiffness, and energy dissipation capacity. So that in the vertical-strip walls, the stiffness increases by 98.1%, and in the cross-strip model's position, the stiffness increases by 127.9%. In the vertical-strip model, the maximum resistance is equal to 108 kN, while in the end cycle, this number is reduced by almost half and reaches 40 kN, in the cross-strip model, the maximum resistance is equal to 104 kN, and in the final cycle, this number decreases by only 13.5% and reaches 90 kN. The scattering of Fe-based strips plays an important role in energy dissipation. Based on the observed behaviors, the greater the scattering, the higher the energy dissipation. The increase was more visible in the walls with the configuration of the crossed Fe-based strips.

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Deformation Behavior of a Shape Memory Alloy: Nitinol

Volume 1: Advanced Energy Systems; Advanced and Digital Manufacturing; Advanced Materials; Aerospace ◽

10.1115/esda2008-59187 ◽

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.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.2095 ◽

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.

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The cyclic response of circular reinforced concrete column to foundation connections strengthened with shape memory alloy bars

Journal of Composite Materials ◽

10.1177/0021998320961440 ◽

2020 ◽

pp. 002199832096144

Author(s):

Mahdieh Miralami ◽

M Reza Esfahani ◽

Mohammadreza Tavakkolizadeh ◽

Reza Khorramabadi ◽

Jalil Rezaeepazhand

Keyword(s):

Energy Dissipation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Load Capacity ◽

Lateral Load ◽

Reference Specimen ◽

Initial Stiffness ◽

Residual Displacement ◽

Cfrp Sheets ◽

Column Foundation

This study presents a new method for strengthening the circular reinforced concrete (RC) column to foundation connections with shape memory alloy (SMA) bars and carbon fiber reinforced polymer (CFRP) sheets. In the experimental part of the study, three specimens of RC column-foundation connections were cast and tested. One specimen was used as the reference specimen without strengthening. Two other specimens were strengthened with longitudinal SMA bars and CFRP sheets. These specimens were under a constant axial compressive load and cyclic lateral displacements, simultaneously. Next, initial stiffness, energy dissipation capacity, lateral load capacity, ductility, and residual displacement of the specimens were investigated. Due to the superelastic behavior of SMA bars, the residual displacement of column-foundation connections was considerably less than that of the reference specimen. Compared to the reference specimen, the SMA-strengthened and SMA-CFRP-strengthened connections recovered 71.59% and 76.57% of the residual displacement. Therefore, SMA bars were able to recover residual displacements under cyclic loading. Also, the combination of the SMA bars with CFRP sheet was a promising solution for enhancing the amount of the energy dissipation, lateral load capacity, initial stiffness, and ductility parameters. Compared to the reference specimen, the energy dissipation, lateral load capacity, initial stiffness, and ductility ratio parameters of SMA-CFRP-strengthened connection increased about 43.45%, 76.20%, 81.69%, and 242.45%, respectively. In the numerical part of the study, a subroutine was applied for modeling the SMA materials. For the analysis, this subroutine was linked with ABAQUS software. The numerical results showed a close correlation with the experimental results.

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

Materials Characterization ◽

10.1016/j.matchar.2009.01.006 ◽

2009 ◽

Vol 60 (8) ◽

pp. 775-782 ◽

Cited By ~ 20

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

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11.65: An axial type self-centering energy dissipation device with shape memory alloy for seismic mitigation

ce/papers ◽

10.1002/cepa.390 ◽

2017 ◽

Vol 1 (2-3) ◽

pp. 3356-3364

Author(s):

Ran Li ◽

Ganping Shu ◽

Zhen Liu ◽

Xiao Lyu ◽

Meihe Chen

Keyword(s):

Energy Dissipation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Seismic Mitigation

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Experimental Research of PFD-SMA Support System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.71-78.4521 ◽

2011 ◽

Vol 71-78 ◽

pp. 4521-4524 ◽

Cited By ~ 1

Author(s):

Ji Gang Zhang ◽

Yan Mei Liu ◽

Yuan Feng Gao ◽

Jian Han

Keyword(s):

Energy Dissipation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Support System ◽

Load Force ◽

Element Analysis ◽

Test Study ◽

Force Increase ◽

The Finite Element Analysis ◽

Good Energy

Pall-typed dampers(PFD) have good energy dissipation, and shape memory alloy(SMA) brace has good super-elastic performance, so the PFD-SMA support system is put forward. Through the test study of PFD-SMA support system, analyze the influence to its hysteretic characteristic by preload force of Pall-typed frictional damper, the stiffness and length parameters of shape memory alloy support. The test results show that PFD-SMA support system s have good energy dissipation and good reposition due to its super-elastic performance, with pre-load force increase, its super-elastic performance acts better, its hysteretic curve show super-elastic performance too, and it verifies the correctness of the finite element analysis.

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