Calibration of a three-dimensional multimechanism shape memory alloy material model for the prediction of the cyclic “attraction” character in binary NiTi alloys

2012 ◽  
Vol 24 (1) ◽  
pp. 70-88 ◽  
Author(s):  
Atef F Saleeb ◽  
Binod Dhakal ◽  
Santo A Padula ◽  
Darrell J Gaydosh
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Three Dimensional ◽  
Material Model ◽  
Cyclic Behavior ◽  
Modeling Framework ◽  
Tension Tests ◽  
High Transformation ◽  
Behavior Characteristics

As typically utilized in applications, a particular shape memory alloy device or component operates under a large number of thermomechanical cycles, hence, the importance of accounting for the cyclic behavior characteristics in modeling and characterization of these systems. To this end, the present work is focused on the characterization of the evolutionary, cyclic behavior of binary 55NiTi (having a moderately-high transformation temperature range). In this study, an extensive set of test data from recent cyclic, isobaric, tension tests was used. Furthermore, for the calibration and characterization of this material, a newly developed, multiaxial, material-modeling framework was implemented. In this framework, multiple, inelastic mechanisms are used to regulate the partitioning of energy dissipation and storage governing the evolutionary thermomechanical response.

Design and Optimization of a Shape Memory Alloy-Based Self-Folding Sheet

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Edwin Peraza-Hernandez ◽  
Darren Hartl ◽  
Edgar Galvan ◽  
Richard Malak
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Three Dimensional ◽  
Building Blocks ◽  
Passive Layer ◽  
Von Mises Stress ◽  
Maximum Temperature ◽  
Radius Of Curvature ◽  
Folding Angle ◽  
The Impact

Origami engineering—the practice of creating useful three-dimensional structures through folding and fold-like operations on two-dimensional building-blocks—has the potential to impact several areas of design and manufacturing. In this article, we study a new concept for a self-folding system. It consists of an active, self-morphing laminate that includes two meshes of thermally-actuated shape memory alloy (SMA) wire separated by a compliant passive layer. The goal of this article is to analyze the folding behavior and examine key engineering tradeoffs associated with the proposed system. We consider the impact of several design variables including mesh wire thickness, mesh wire spacing, thickness of the insulating elastomer layer, and heating power. Response parameters of interest include effective folding angle, maximum von Mises stress in the SMA, maximum temperature in the SMA, maximum temperature in the elastomer, and radius of curvature at the fold line. We identify an optimized physical realization for maximizing folding capability under mechanical and thermal failure constraints. Furthermore, we conclude that the proposed self-folding system is capable of achieving folds of significant magnitude (as measured by the effective folding angle) as required to create useful 3D structures.

Characterization of Reversibly-Actuating Shape Memory Alloy Foils Produced By Planar Flow Casting

2021 ◽  
Author(s):  
Ling Chen ◽  
David Renshaw ◽  
Michael Kellam ◽  
Ritaban Dutta ◽  
Daniel Liang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Planar Flow ◽  
Planar Flow Casting

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

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.

Complex transformation field created by geometrical gradient design of NiTi shape memory alloy

2017 ◽  
Vol 10 (01) ◽  
pp. 1740011 ◽  
Author(s):  
Reza Bakhtiari ◽  
Bashir S. Shariat ◽  
Fakhrodin Motazedian ◽  
Zhigang Wu ◽  
Junsong Zhang ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Deformation Behavior ◽  
Stress Gradient ◽  
Tensile Loading ◽  
Niti Shape Memory Alloy ◽  
Mechanical Behaviors ◽  
Modeling Framework ◽  
Complex Transformation ◽  
Pseudoelastic Behavior

Owing to geometrical non-uniformity, geometrically graded shape memory alloy (SMA) structures by design have the ability to exhibit different and novel thermal and mechanical behaviors compared to geometrically uniform conventional SMAs. This paper reports a study of the pseudoelastic behavior of geometrically graded NiTi plates. This geometrical gradient creates partial stress gradient over stress-induced martensitic transformation, providing enlarged stress controlling interval for shape memory actuation. Finite element modeling framework has been established to predict the deformation behavior of such structures in tensile loading cycles, which was validated by experiments. The modeling results show that the transformation mostly propagates along the gradient direction as the loading level increases.

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