Torsional Behavior of Shape Memory Alloy Tubes for Biomedical Applications

Shape memory alloys have been implemented in various applications throughout aerospace, biomedical, and various other fields. Some currently investigated applications of shape memory alloys include biomedical stents, rotary blade actuators, and pedicle screws for securing osteoporotic vertebrae. There have been many models developed by previous authors that discuss the reactions of this alloy in tension, compression, and one dimensional bending. It was the goal of this investigation to expand upon previous works to model the behavior of a shape memory alloy tube in pure torsion. The motivation for this investigation was the biomedical applications of this alloy. Because of its distinct properties of superelasticity and shape memory effect, the alloy is ideal for the design and implementation of medical devices that are smaller and more efficient than previous methods. The goal of this investigation was to model the properties of an SMA tube in torsion for use in an active orthoses for the treatment neuromuscular disorders and various other biomedical devices which involve the implementation of nitinol tubes in torsion. To this end, a model using COMSOL Multiphysics was developed which, in turn, will aid in predicting the behavior of an SMA tube under a torsional load and allow for calculation of an optimal torque tube for our applications. The outputs gained from this model were the angle of deformation under an applied torque, the resultant torque upon unloading of the tube, and the stress-strain relationships. From this information, different tube geometries will be experimentally tested to determine the best design for implementation. Once the analytical forces were determined from the SMA tubes using the COMSOL model, these results were then compared to experimental values from previous works to evaluate the accuracy of the model for the desired conditions.

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Shape memory alloy–actuated prestressed composites with application to morphing automotive fender skirts

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x18812702 ◽

2018 ◽

Vol 30 (3) ◽

pp. 479-494 ◽

Cited By ~ 6

Author(s):

Venkata Siva C Chillara ◽

Leon M Headings ◽

Ryohei Tsuruta ◽

Eiji Itakura ◽

Umesh Gandhi ◽

...

Keyword(s):

Shape Memory Alloy ◽

Shape Memory Alloys ◽

Shape Memory ◽

Smart Materials ◽

Design Procedure ◽

Building Blocks ◽

Smart Composite ◽

Thermally Induced ◽

One Dimensional ◽

Flat Shape

This work presents smart laminated composites that enable morphing vehicle structures. Morphing panels can be effective for drag reduction, for example, adaptive fender skirts. Mechanical prestress provides tailored curvature in composites without the drawbacks of thermally induced residual stress. When driven by smart materials such as shape memory alloys, mechanically-prestressed composites can serve as building blocks for morphing structures. An analytical energy-based model is presented to calculate the curved shape of a composite as a function of force applied by an embedded actuator. Shape transition is modeled by providing the actuation force as an input to a one-dimensional thermomechanical constitutive model of a shape memory alloy wire. A design procedure, based on the analytical model, is presented for morphing fender skirts comprising radially configured smart composite elements. A half-scale fender skirt for a compact passenger car is designed, fabricated, and tested. The demonstrator has a domed unactuated shape and morphs to a flat shape when actuated using shape memory alloys. Rapid actuation is demonstrated by coupling shape memory alloys with integrated quick-release latches; the latches reduce actuation time by 95%. The demonstrator is 62% lighter than an equivalent dome-shaped steel fender skirt.

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An analytical model for crack monitoring of the shape memory alloy intelligent concrete

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x19880010 ◽

2019 ◽

Vol 31 (1) ◽

pp. 100-116 ◽

Cited By ~ 1

Author(s):

Bingfei Liu ◽

Qingfei Wang ◽

Kai Yin ◽

Liwen Wang

Keyword(s):

Shape Memory Alloy ◽

Constitutive Model ◽

Shape Memory Alloys ◽

Shape Memory ◽

Three Dimensional ◽

Three Dimensional Model ◽

One Dimensional ◽

Monitoring Model ◽

Crack Monitoring ◽

The One

A theoretical model for the crack monitoring of the shape memory alloy intelligent concrete is presented in this work. The mechanical properties of shape memory alloy materials are first given by the experimental test. The one-dimensional constitutive model of the shape memory alloys is reviewed by degenerating from a three-dimensional model, and the behaviors of the shape memory alloys under different working conditions are then discussed. By combining the electrical resistivity model and the one-dimensional shape memory alloy constitutive model, the crack monitoring model of the shape memory alloy intelligent concrete is given, and the relationships between the crack width of the concrete and the electrical resistance variation of the shape memory alloy materials for different crack monitoring processes of shape memory alloy intelligent concrete are finally presented. The numerical results of the present model are compared with the published experimental data to verify the correctness of the model.

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Design of a New Biocompatible Ti-Based Shape Memory Alloy and Its Superelastic Deformation Behaviour

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.2087 ◽

2010 ◽

Vol 654-656 ◽

pp. 2087-2090 ◽

Cited By ~ 2

Author(s):

Jian Yu Xiong ◽

Yun Cang Li ◽

Peter D. Hodgson ◽

Cui E Wen

Keyword(s):

Shape Memory Alloy ◽

Shape Memory Alloys ◽

Shape Memory ◽

Biomedical Applications ◽

Deformation Behaviour ◽

Vacuum Arc ◽

Orbital Method ◽

Arc Melting ◽

Titanium Nickel ◽

Ice Water

Titanium-nickel (Ti-Ni) shape memory alloys have been widely used for biomedical applications in recent years. However, it is reported that Ni is allergic and possibly carcinogenic for the human body. Therefore, it is desirable to develop new Ni-free Ti-based shape memory alloys for biomedical applications. In the present study, a new Ti-18Nb-5Mo-5Sn (wt.%) alloy, containing only biocompatible alloying elements, was designed with the aid of molecular orbital method and produced by vacuum arc melting. Both β and α″ martensitic phases were found to coexist in the alloy after ice-water quenching, indicating the martensitic transformation. The phase transformation temperatures of the Ti-18Nb-5Mo-5Sn alloy were Ms = 7.3 °C, Mf = −31.0 °C, As = 9.9 °C, and Af = 54.8 °C. Superelasticity was observed in the alloy at a temperature higher than the Af temperature. A totally recovered strain of 3.5 % was achieved for the newly designed Ti-based shape memory alloy with a pre-strain of 4 %.

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Rigidity of Branching Microstructures in Shape Memory Alloys

Archive for Rational Mechanics and Analysis ◽

10.1007/s00205-021-01679-8 ◽

2021 ◽

Author(s):

Theresa M. Simon

Keyword(s):

Shape Memory Alloy ◽

Shape Memory Alloys ◽

Shape Memory ◽

Differential Inclusion ◽

Linearized Strain ◽

Weak Limits ◽

All Solutions ◽

Rank One ◽

Branched Structures ◽

Habit Planes

AbstractWe analyze generic sequences for which the geometrically linear energy $$\begin{aligned} E_\eta (u,\chi )\,{:}{=} \,\eta ^{-\frac{2}{3}}\int _{B_{1}\left( 0\right) } \left| e(u)- \sum _{i=1}^3 \chi _ie_i\right| ^2 \, \mathrm {d}x+\eta ^\frac{1}{3} \sum _{i=1}^3 |D\chi _i|({B_{1}\left( 0\right) }) \end{aligned}$$ E η ( u , χ ) : = η - 2 3 ∫ B 1 0 e ( u ) - ∑ i = 1 3 χ i e i 2 d x + η 1 3 ∑ i = 1 3 | D χ i | ( B 1 0 ) remains bounded in the limit $$\eta \rightarrow 0$$ η → 0 . Here $$ e(u) \,{:}{=}\,1/2(Du + Du^T)$$ e ( u ) : = 1 / 2 ( D u + D u T ) is the (linearized) strain of the displacement u, the strains $$e_i$$ e i correspond to the martensite strains of a shape memory alloy undergoing cubic-to-tetragonal transformations and the partition into phases is given by $$\chi _i:{B_{1}\left( 0\right) } \rightarrow \{0,1\}$$ χ i : B 1 0 → { 0 , 1 } . In this regime it is known that in addition to simple laminates, branched structures are also possible, which if austenite was present would enable the alloy to form habit planes. In an ansatz-free manner we prove that the alignment of macroscopic interfaces between martensite twins is as predicted by well-known rank-one conditions. Our proof proceeds via the non-convex, non-discrete-valued differential inclusion $$\begin{aligned} e(u) \in \bigcup _{1\le i\ne j\le 3} {\text {conv}} \{e_i,e_j\}, \end{aligned}$$ e ( u ) ∈ ⋃ 1 ≤ i ≠ j ≤ 3 conv { e i , e j } , satisfied by the weak limits of bounded energy sequences and of which we classify all solutions. In particular, there exist no convex integration solutions of the inclusion with complicated geometric structures.

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Crystallographic Attributes of a Shape-Memory Alloy

Journal of Engineering Materials and Technology ◽

10.1115/1.2816005 ◽

1999 ◽

Vol 121 (1) ◽

pp. 93-97 ◽

Cited By ~ 2

Author(s):

Kaushik Bhattacharya

Keyword(s):

Shape Memory Alloy ◽

Shape Memory Alloys ◽

Shape Memory ◽

Nickel Titanium ◽

Potential Applications

Shape-memory Alloys are attractive for many potential applications. In an attempt to provide ideas and guidelines for the development of new shape-memory alloys, this paper reports on a series of investigations that examine the reasons in the crystallography that make (i) shape-memory alloys special amongst martensites and (ii) Nickel-Titanium special among shape-memory alloys.

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Design of Shape Memory Alloy Springs With Applications in Vibration Control

Journal of Vibration and Acoustics ◽

10.1115/1.2930305 ◽

1993 ◽

Vol 115 (1) ◽

pp. 129-135 ◽

Cited By ~ 44

Author(s):

C. Liang ◽

C. A. Rogers

Keyword(s):

Shape Memory Alloy ◽

Shape Memory Alloys ◽

Shape Memory ◽

Vibration Control ◽

Young’S Modulus ◽

Young's Modulus ◽

Design Method ◽

Control Area ◽

Spring Constant ◽

Damping Capacity

Shape memory alloys (SMAs) have several unique characteristics, including their Young’s modulus-temperature relations, shape memory effects, and damping characteristics. The Young’s modulus of the high-temperature austenite of SMAs is about three to four times as large as that of low-temperature martensite. Therefore, a spring made of shape memory alloy can change its spring constant by a factor of three to four. Since a shape memory alloy spring can vary its spring constant, provide recovery stress (shape memory effect), or be designed with a high damping capacity, it may be useful in adaptive vibration control. Some vibration control concepts utilizing the unique characteristics of SMAs will be presented in this paper. Shape memory alloy springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some design approaches based upon linear theory have been proposed for shape memory alloy springs. A more accurate design method for SMA springs based on a new nonlinear thermomechanical constitutive relation of SMA is also presented in this paper.

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Cold Bending a Ni-Ti Shape Memory Alloy Wire

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.661.98 ◽

2015 ◽

Vol 661 ◽

pp. 98-104 ◽

Cited By ~ 3

Author(s):

Kuang-Jau Fann ◽

Pao Min Huang

Keyword(s):

Shape Memory Alloy ◽

Shape Memory Alloys ◽

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Room Temperature ◽

Aging Treatment ◽

Treatment Temperature ◽

Bending Test ◽

Solution Treatment Temperature

Because of being in possession of shape memory effect and superelasticity, Ni-Ti shape memory alloys have earned more intense gaze on the next generation applications. Conventionally, Ni-Ti shape memory alloys are manufactured by hot forming and constraint aging, which need a capital-intensive investment. To have a cost benefit getting rid of plenty of die sets, this study is aimed to form Ni-Ti shape memory alloys at room temperature and to age them at elevated temperature without any die sets. In this study, starting with solution treatments at various temperatures, which served as annealing process, Ni-rich Ni-Ti shape memory alloy wires were bent by V-shaped punches in different curvatures at room temperature. Subsequently, the wires were aged at different temperatures to have shape memory effect. As a result, springback was found after withdrawing the bending punch and further after the aging treatment as well. A higher solution treatment temperature or a smaller bending radius leads to a smaller springback, while a higher aging treatment temperature made a larger springback. This springback may be compensated by bending the wires in further larger curvatures to keep the shape accuracy as designed. To explore the shape memory effect, a reverse bending test was performed. It shows that all bent wires after aging had a shape recovery rate above 96.3% on average.

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