Axial Compressive Behavior of Single-Stage Bellows of TiNi Shape Memory Alloy for Seismic Applications

2005 ◽  
Vol 475-479 ◽  
pp. 2055-2058 ◽  
Author(s):  
Hiromasa Semba ◽  
Nagatoshi Okabe ◽  
Toru Yamaji ◽  
Keisuke Okita ◽  
Kiyoshi Yamauchi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Large Strain ◽  
Axial Direction ◽  
Single Stage ◽  
Seismic Protection ◽  
Compression Tests ◽  
Compressive Behavior ◽  
Heat Treated ◽  
Energy Absorbing

The bellows formed of TiNi shape memory alloy (SMA) is proposed as a new type of seismic protection device. The bellows structure is known to have lower rigidity along the axial direction through effect of its shape. TiNi is known to be one of the most typical SMAs, which have high damping characteristics for dynamics engaged in its twin formation under martensite state and have the ability to recover completely from the large strain after unloaded and or heated. In this study, fundamental compressive behavior of TiNi bellows was investigated and discussed. Several shapes of TiNi single-stage bellows produced by rubber bulge method were prepared. They were heat-treated for some heat treatments and then examined on compression tests. Based on the results, the relationships among the bellows shapes and the stiffness, energy-absorbing capacity and so on were clarified. Finally, it was found from these results that single-stage bellows of TiNi SMA could be used as one of seismic protection devices.

Axial Compressive Behavior of Single-Stage Bellows of TiNi Shape Memory Alloy for Seismic Applications

2005 ◽  
pp. 2055-2058
Author(s):  
Hiromasa Semba ◽  
Nagatoshi Okabe ◽  
Toru Yamaji ◽  
Keisuke Okita ◽  
Kiyoshi Yamauchi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Single Stage ◽  
Compressive Behavior ◽  
Seismic Applications

Processing of Single-Stage Bellows of TiNi Shape Memory Alloy Using Rubber Bulge Method

2005 ◽  
Vol 475-479 ◽  
pp. 2059-2062 ◽  
Author(s):  
Hiromasa Semba ◽  
Nagatoshi Okabe ◽  
Toru Yamaji ◽  
Keisuke Okita ◽  
Kiyoshi Yamauchi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Cold Working ◽  
Large Strain ◽  
Longitudinal Direction ◽  
Single Stage ◽  
Damping Characteristics ◽  
Annealing Conditions ◽  
New Type ◽  
Typical Shape

The bellows formed of TiNi shape memory alloy is proposed as a new type of seismic protection device. The bellows structure is known to have lower rigidity along the longitudinal direction through effect of its shape. On the other hand, TiNi is known to be one of the most typical shape memory alloys, which have high damping characteristics for dynamics engaged in its twin formation under martensite state and have the ability to recover completely from the large strain (even such as 8%) after unloaded and or heated. This paper describes a processing method of a single-stage bellows of TiNi shape memory alloy using rubber bulge method. Thin-walled TiNi tubes subjected to cold working were prepared. Several annealing conditions for the process were examined and the appropriate one was discussed. Then the rubber bulge method of displacement control was introduced. Finally, the procedure of the process including heat treatment was clarified.

Nickel–titanium shape memory alloy mechanical components produced by investment casting

2018 ◽  
Vol 29 (19) ◽  
pp. 3748-3757 ◽  
Author(s):  
Jackson de Brito Simões ◽  
Carlos José de Araújo
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Investment Casting ◽  
Mechanical Characterization ◽  
Nickel Titanium ◽  
Compression Tests ◽  
Thermoelastic Martensitic Transformation ◽  
Scanning Calorimetry ◽  
Helical Springs ◽  
Mechanical Components

This work aimed to produce mechanical components of nickel–titanium shape memory alloys using investment casting processes. Then, in order to validate processing, different designs of nickel–titanium shape memory alloy components as staple implants, Belleville springs, meshes, helical springs, screws and hexagonal honeycombs were produced and submitted to thermal and mechanical characterization. Thermoelastic martensitic transformation of the nickel–titanium shape memory alloy parts was determined by differential scanning calorimetry and electrical resistance with temperature, while the superelastic behaviour was verified by cyclic tensile and compression tests. It has been demonstrated that the employed investment casting processes are suitable to manufacture nickel–titanium shape memory alloy mechanical components with simple and complicated designs as well as functional properties related to phase transformation and superelasticity.

scholarly journals Effect of Heat Treatment Temperature on Martensitic Transformation and Superelasticity of the Ti49Ni51 Shape Memory Alloy

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2539 ◽  
Author(s):  
Peiyou Li ◽  
Yongshan Wang ◽  
Fanying Meng ◽  
Le Cao ◽  
Zhirong He
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thermal Hysteresis ◽  
Treatment Temperature ◽  
Heat Treated ◽  
Different Temperatures ◽  
Tini Phase ◽  
Rapidly Solidified

The martensitic transformation and superelasticity of Ti49Ni51 shape memory alloy heat-treatment at different temperatures were investigated. The experimental results show that the microstructures of as-cast and heat-treated (723 K) Ni-rich Ti49Ni51 samples prepared by rapidly-solidified technology are composed of B2 TiNi phase, and Ti3Ni4 and Ti2Ni phases; the microstructures of heat-treated Ti49Ni51 samples at 773 and 823 K are composed of B2 TiNi phase, and of B2 TiNi and Ti2Ni phases, respectively. The martensitic transformation of as-cast Ti49Ni51 alloy is three-stage, A→R→M1 and R→M2 transformation during cooling, and two-stage, M→R→A transformation during heating. The transformations of the heat-treated Ti49Ni51 samples at 723 and 823 K are the A↔R↔M/A↔M transformation during cooling/heating, respectively. For the heat-treated alloy at 773 K, the transformations are the A→R/M→R→A during cooling/heating, respectively. For the heat-treated alloy at 773 K, only a small thermal hysteresis is suitable for sensor devices. The stable σmax values of 723 and 773 K heat-treated samples with a large Wd value exhibit high safety in application. The 773 and 823 K heat-treated samples have large stable strain–energy densities, and are a good superelastic alloy. The experimental data obtained provide a valuable reference for the industrial application of rapidly-solidified casting and heat-treated Ti49Ni51 alloy.

scholarly journals Uniaxial Compressive Behavior of Concrete Columns Confined with Superelastic Shape Memory Alloy Wires

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1227 ◽  
Author(s):  
Chenkai Hong ◽  
Hui Qian ◽  
Gangbing Song
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Seismic Design ◽  
Large Deformations ◽  
Axial Loading ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Loading Capacity ◽  
Compressive Behavior ◽  
Concrete Cylinders

Superelastic shape memory alloy (SMA) exhibits the ability to undergo large deformations before reverting back to its undeformed shape following the removal of the load. This unique property underlies its great potential in the seismic design and retrofitting of structure members. In this paper, superelastic SMA wires were utilized to confine concrete cylinders to enhance their axial compressive behavior. The axial carrying and deformation capacities of SMA-confined concrete cylinders are assessed by uniaxial compression testing on a total of eight SMA-confined concrete columns and one unconfined column. The influence of the amount of SMA and the prestrain level of SMA wires, as well as the reinforcing mode, on the axial carrying and deformation capacity of confined concrete columns were considered. The analysis focuses on the axial carrying capacity and deformation performance of concrete columns reinforced with superelastic SMA under different loading conditions. Based on the experimental data and analysis results, it is found that superelastic SMA wires can increase the axial loading capacity and enhance deformation performance of concrete columns. Under the same loading condition, the ultimate bearing capacity of SMA-confined concrete columns increases as the increasing of the amount of SMA wire. The results of this study verify the effectiveness of superelastic SMA in enhancing the loading capacity and deformation behavior of concrete cylinders.

Smart Crash Management by Switching the Crash Behavior of Fiber-Reinforced Plastic (FRP) Energy Absorbers With Shape Memory Alloy (SMA) Wires

2013 ◽  
Author(s):  
Moritz Hübler ◽  
Sebastian Nissle ◽  
Martin Gurka ◽  
Sebastian Schmeer ◽  
Ulf Paul Breuer
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Essential Element ◽  
Load Level ◽  
Switching Behavior ◽  
Fiber Reinforced ◽  
Reinforced Plastics ◽  
Reinforced Plastic ◽  
Energy Absorbers ◽  
Energy Absorbing

In this paper two innovative concepts for adjustable energy absorbing elements are presented. These absorbers can serve as an essential element in a smart crash management system e.g. for automotive applications. The adaptability is based on the basic idea of adjusting the stiffness of the absorber in relation to the actual load level in a crash event. Therefore the whole length of the absorber element can be used for energy dissipation. The adjustable absorbers are made from fiber reinforced plastics and shape memory alloy wires as actuating elements. Two possibilities for the basic design of the absorber elements are shown, the performance of the actuating SMA elements is characterized in detail and the switching behavior of the whole elements, between a stiff “on” state and a flexible “off” state, is measured.

An experimental approach to the thermomechanical characterization of a NiTiCu shape memory alloy using strain gauges

2016 ◽  
Vol 231 (1-2) ◽  
pp. 113-121
Author(s):  
Albert Fabregat-Sanjuan ◽  
Francesc Ferrando Piera ◽  
Silvia De la Flor López
Keyword(s):  
Shape Memory Alloy ◽  
Shear Modulus ◽  
Shape Memory ◽  
Twist Angle ◽  
Strain Tensor ◽  
Strain Ratio ◽  
Strain Gauges ◽  
Compression Tests ◽  
Thermal Chamber

In this work, a characterization of a NiTiCu (Ti44.6Ni5Cu (at.%)) shape memory alloy (tube specimens) has been done via tension, compression and torsion tests conditions. Torsion tests were done in a special homemade equipment, which is based on an instrumented dividing head with a specifically designed thermal chamber. This configuration is able to measure torque and twist angle with isothermal tests at different temperatures as well as to apply thermal cycles with a fixed twist angle. Moreover, tube specimens were instrumented with stacked strain gauges rosettes in order to obtain the strain tensor. Strain gauges were also used to calibrate the equipment and to identify the real stress state in torsion tests. The results have shown differences between the shear modulus measured on torsion tests and the shear modulus calculated from the measurements at tension and compression tests due to the tension/compression asymmetry and a non-constant strain ratio value. Thermal cycling tests at different values of fixed twist angles not only have led to characterize the evolution of torque as a function of the temperature but also to understand the different interacting mechanisms in torsion tests.

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