A SMART POLYMER COMPOSITE ACTUATOR WITH THIN SMA STRIPS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3733-3738 ◽  
Author(s):  
CHEOL KIM
Keyword(s):  
Mathematical Model ◽  
Phase Transformation ◽  
Shape Memory ◽  
Constitutive Equations ◽  
Composite Shell ◽  
Large Strain ◽  
Shell Structures ◽  
Mechanical Behaviors ◽  
Smart Polymer ◽  
Shape Changes

The characteristics of SMA to provide a high force and a large strain make them a good candidate for an actuator for controlling the shape of smart structures. Using a mathematical model that captures the thermo-mechanical behaviors and 2-way shape memory effect (TWSME) of SMA, some smart shell structures were analyzed numerically and experimentally. The deflections of morphing shells to that thin SMA strips are attached were investigated depending on various phase transformation temperatures. SMA strips start to transform from the martensitic into the austenitic state upon actuation through resistive heating, simultaneously recover the prestrain, and thus cause the shell structures to deform three dimensionally. The behaviors of composite shells with SMA strips were analyzed using FEM and 3-D constitutive equations of SMA. Several morphing composite shell structures were fabricated and their experimental shape changes depending on temperatures were compared to the numerical results. That two results show good correlations indicates FEA and 3-D constitutive equations are accurate enough to utilize them for the design of smart shell structures for various applications.

Investigation on Mechanical Behaviors of Shape Memory Alloy Torsion Rod

2011 ◽  
Vol 179-180 ◽  
pp. 455-458
Author(s):  
Bo Zhou ◽  
Zhen Qing Wang ◽  
Yan Ju Liu ◽  
Jin Song Leng
Keyword(s):  
Phase Transformation ◽  
Constitutive Equation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Martensitic Phase Transformation ◽  
Mechanical Behaviors ◽  
Transformation Temperatures ◽  
Mechanics Of Materials ◽  
Niti Sma ◽  
The Relationship

DSC test is carried out to determine the phase transformation temperatures of a NiTi SMA, which include martensitic starting temperature, martensitic finishing temperature, austenitic starting temperature and austenitic finishing temperature. The mechanical behaviors of shape memory alloy (SMA) torsion rod are investigated by using Zhou’s shear constitutive equation of SMA and the theorem of circular shaft in mechanics of materials. A critical torque equation is developed to describe the relationship between the martensitic phase transformation critical torque of SMA torsion rod and temperature.

Effects of Annealing on Phase Transformation and Mechanical Behaviors of NiTi Shape Memory Alloy Ultra Thin Sheet

2007 ◽  
Vol 546-549 ◽  
pp. 2257-2260
Author(s):  
Ling Jie Meng ◽  
Yan Li ◽  
Xin Qing Zhao ◽  
Hui Bin Xu
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
Thin Sheet ◽  
Niti Shape Memory Alloy ◽  
Electric Resistance ◽  
Mechanical Behaviors ◽  
Martensitic Transformation Temperature ◽  
Cold Rolled ◽  
Transformation Stress ◽  
Niti Shape Memory Alloys

The phase transformation and mechanical behaviors of cold-rolled NiTi shape memory alloys ultra-thin sheet with 100μm in thickness are investigated. The transformation behaviors of the NiTi sheet are found to be remarkably influenced by heat treatment using electric resistance vs. temperature measurements. The martensitic transformation temperature reduced by annealing at 400°C or 600°C, and R-phase transformation appears when annealing at 400°C. The martensitic reorientation occurs when the NiTi sheets annealed at 400°C is deformed at room temperature and the maximum shape memory strain is 3.5% at 100% recovery ratio. For the NiTi sheets annealed at 600°C, a superelastic strain of 5% and a transformation stress about 500MPa are achieved.

The Research of the Difference between Small-Strain and Large-Strain Formulations for Shape Memory Alloys

2012 ◽  
Vol 229-231 ◽  
pp. 3-9
Author(s):  
Jie Yao ◽  
Young Hong Zhu ◽  
Yun Zhang Wu
Keyword(s):  
Phase Transformation ◽  
Constitutive Model ◽  
Shape Memory ◽  
Uniaxial Tension ◽  
Driving Force ◽  
Large Strain ◽  
Small Deformation ◽  
Small Strain ◽  
Proportional Loading ◽  
The Difference

Based on thermodynamics and phase transformation driving force, we apply a SMA constitutive model to analyze the large and small deformation of SMA materials. Simulations under different loading, uniaxial tension and shear conditions, illustrate the characteristics of the model in large strain deformation and small strain deformation. The results indicate that the difference between the two methods is small under the uniaxial tension case, while the large deformation and the small deformation results are very different under shear deformation case. It lays a foundation for the further studies of the constitutive model of SMA, especially in the multiaxial non-proportional loading aspects.

Influence of Small-Strain and Large-Strain Methods on Mechanical Behaviors in Shape Memory Alloys

2011 ◽  
Vol 328-330 ◽  
pp. 1556-1559
Author(s):  
Yun Zhang Wu ◽  
Yu Ping Zhu ◽  
Guan Suo Dui
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shear Deformation ◽  
Uniaxial Tension ◽  
Phenomenological Model ◽  
Large Strain ◽  
Small Strain ◽  
Thermodynamic Theory ◽  
Mechanical Behaviors ◽  
The Difference

Based on thermodynamic theory, a phenomenological model of shape memory alloy is provided. Simulations under different loading illustrate the influence of large-strain deformation and small-strain deformation on the characteristics of the model. The results indicate that the difference between the two methods is small under uniaxial tension case, while the influence is very large under shear deformation case.

Mechanical Behaviors of Torsion Actuator of Shape Memory Alloy

2008 ◽  
Vol 385-387 ◽  
pp. 213-216 ◽  
Author(s):  
Bo Zhou ◽  
Zhen Qing Wang ◽  
Sung Ho Yoon ◽  
Guang Ping Zou
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Model ◽  
Solid Mechanics ◽  
Mechanical Behaviors ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Relationship Of ◽  
The Relationship

A shape memory alloy (SMA) torsion actuator is designed by using SMA wires and a thin-walled tube. A mechanical model, which predicts the thermo-mechanical behaviors of the SMA torsion actuator, is developed based on the knowledge of solid mechanics and constitutive relation of SMA. The relationship of the torsion-angle and temperature of the SMA torsion actuator is numerically described by using the mechanical model coupled with Tanaka’s, Liang’s and Zhou’s phase transformation models of SMA respectively. Results show the mechanical model well predict the thermo-mechanical behaviors of the SMA torsion actuator.

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