Experimental and Analytical Studies on Stress-Strain-Temperature Relationship of TiNi Shape Memory Alloy Subjected to Cyclic Loadings.

Concerning important infrastructures and civil structures, they need real time detection during the service, such as high-rise buildings, cables, bridges and dams. Therefore, it is necessary to study sensing property of shape memory alloy (SMA) for developing a sensing element embedded in the structures to carry out damage detection. In this paper, change rate of resistance-stress-strain relationship of TiNi and TiNiCu shape memory alloys (SMAs) under elongation is examined. Tests are conducted in MTS at room temperature for the mechanical and strain-sense properties. According to the test results, it is concluded that TiNi and TiNiCu in martensitic phase and austenitic TiNi SMA wires have good strain-sense property. The change rate of resistance of SMA wires has a linear relation with the applied strain. Additionally, stress-strain relation is also predicted by Brinson Model. This study is devoted to sensing properties of TiNi and TiNiCu shape memory alloy.

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Anomalous stress-strain behavior of NiTi shape memory alloy close to the border of superelastic window

Scripta Materialia ◽

10.1016/j.scriptamat.2021.114135 ◽

2021 ◽

Vol 204 ◽

pp. 114135

Author(s):

Xiebin Wang ◽

Xiayang Yao ◽

Dominique Schryvers ◽

Bert Verlinden ◽

Guilong Wang ◽

...

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Niti Shape Memory Alloy ◽

Stress Strain ◽

Strain Behavior

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Analysis and Design of a Shape Memory Alloy Actuated Arm to Replicate Human Biomechanics

Volume 1: Multifunctional Materials; Mechanics and Behavior of Active Materials; Integrated System Design and Implementation; Structural Health Monitoring ◽

10.1115/smasis2016-9018 ◽

2016 ◽

Author(s):

Cody Wright ◽

Onur Bilgen

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Biceps Brachii ◽

Characteristic Curve ◽

Stress Strain ◽

Analysis And Design ◽

Human Arm ◽

Linear Spring ◽

Mechanism Kinematic

Shape memory alloy actuators paired in an antagonistic arrangement can be used to produce mechanisms that replicate human biomechanics. To investigate this proposal, the biomechanical articulation of the elbow by means of the biceps brachii muscle are compared with that of a shape memory alloy actuated arm. Initially, the movement of the human arm is modeled as a single degree of freedom rocker-slider mechanism. Using this model, a purely kinematical analysis is performed on the rigid body rocker-slider. Force analysis follows by modeling the muscle as a simple linear spring. Torque, rocking angle, and energy are calculated for a range of rocker-slider geometries. Actuator characterization of the SMA wire is conducted by experimentally determining the stress-strain curves for the martensite detwinned and full austenite states. Using the experimentally obtained stress-strain curves, nonlinear and linear theoretical actuator characteristic curves are produced for the isolated SMA wire. Using the theoretical actuator characteristic curve on the rocker-slider mechanism, kinematic and force analyses are performed for both the nonlinear and linear actuated mechanisms. To compare to biomechanics, a literature survey is performed on human musculotendon and skeletal lengths and introduced to the kinematic analysis. Examination of biological and mechanical results are then discussed.

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Model based design of antagonistic shape memory alloy spring devices

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x18770880 ◽

2018 ◽

Vol 29 (12) ◽

pp. 2619-2640 ◽

Cited By ~ 1

Author(s):

Efthymios Kolyvas ◽

Anthony Tzes

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Model Based ◽

Operational Profile ◽

Time Work ◽

Two Factors ◽

Internal Forces ◽

Actuation Scheme ◽

Geometric Relationship ◽

Relationship Of

Shape memory alloy actuated devices employing a network of antagonistic components can reach an equilibrium of the internal forces by multiple sets of individual force magnitudes. In networks of star topologies particularly, the actuators are placed radially with one end connected at a common node. The ability to produce multiple sets of force equilibria suggests then that similar motions of the common node correspond to different thermomechanical paths. Two factors linked to this behavior are examined in this work, namely the initial design of the antagonistic system and the operational profile used during actuation. A shape memory alloy model is initially constructed based on an elementary hysteresis operator to produce a direct representation of the shape memory alloy behavior in the force–deformation plane. This description enables the identification of the operating point for the actuator by the geometric relationship of these models. In the second part, the placement of the antagonists is guided by the model based on specifications on the range of the workspace and the internal forces. The antagonistic operation is finally compared, in terms of time, work produced, and energy consumption, for a bang-bang (minimum time controller for the actuator) and a bang-off-bang (minimum internal forces for the system) actuation scheme.

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