Depth dependency of indentation hardness during solid-state phase transition of shape memory alloys

2011 ◽  
Vol 99 (2) ◽  
pp. 021901 ◽  
Author(s):  
Abbas Amini ◽  
Wenyi Yan ◽  
Qingping Sun
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Indentation Hardness ◽  
Depth Dependency

Phenomenological Models of Solid State Actuators for Network Based System Modelling

2014 ◽  
Author(s):  
Johannes Ziske ◽  
Fabian Ehle ◽  
Holger Neubert
Keyword(s):  
Solid State ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Magnetic Flux Density ◽  
System Modelling ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Design And Optimization ◽  
Highly Nonlinear

Smart materials, such as thermal or magnetic shape memory alloys, provide interesting characteristics for new solid state actuators. However, their behavior is highly nonlinear and determined by strong hysteresis effects. This complex behavior must be adequately considered in simulation models which can be applied for efficient actuator design and optimization. We present a new phenomenological lumped element model for magnetic shape memory alloys (MSM). The model takes into account the two-dimensional hysteresis of the magnetic field induced strain as a function of both the compressive stress and the magnetic flux density. It is implemented in Modelica. The model bases on measured limiting hysteresis surfaces which are material specific. An extended Tellinen hysteresis modeling approach is used to calculate inner hysteresis trajectories in between the limiting surfaces. The developed model provides sufficient accuracy with low computational effort compared to finite element models. Thus, it is well suited for system design and optimization based on network models. This is demonstrated with exemplary models of MSM based actuators. System models and simulation results are shown and evaluated for different topologies.

A Three-Phase Constitutive Model for TiNiNb Shape Memory Alloys

2010 ◽  
Vol 97-101 ◽  
pp. 660-666
Author(s):  
Jun Wang ◽  
Zhi Ming Hao ◽  
Ping An Shi ◽  
Shao Rong Yu ◽  
Wei Fen Li
Keyword(s):  
Phase Transition ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Conventional Theory ◽  
Material Parameters ◽  
Three Phase ◽  
The Individual

A three-phase constitutive model for TiNiNb shape memory alloys (SMAs) is proposed based on the fact that TiNiNb SMAs are dynamically composed of austenite, martensite and -Nb phases. In the considered ranges of stress and temperature, the behaviors of austenite, martensite and -Nb phases are assumed to be elastoplastic, and the behavior of an SMA is regarded as the dynamic combination of the individual behavior of each phase. Then a macroscopic constitutive description for TiNiNb SMAs is obtained by the conventional theory of plasticity, the theory of mixture, the theory of inclusion, and the description of phase transition by Tanaka. The method for determination of the material parameters is given. This constitutive model can describe the main characteristics of SMAs, such as ferrcelasticity, pseudoelasticity and shape memory effect.

Improving shape memory alloys for solid-state cooling

Scilight ◽  
2020 ◽  
Vol 2020 (24) ◽  
pp. 241110
Author(s):  
Jodi Ackerman Frank
Keyword(s):  
Solid State ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Solid State Cooling

EFFECT OF TRANSFORMATION VOLUME STRAIN ON THE SPHERICAL INDENTATION OF SHAPE MEMORY ALLOYS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5957-5964 ◽  
Author(s):  
WENYI YAN ◽  
QINGPING SUN ◽  
HONG-YUAN LIU
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Indentation Depth ◽  
Mechanical Response ◽  
Spherical Indentation ◽  
Indentation Hardness ◽  
Volume Strain ◽  
Volume Contraction ◽  
Indentation Force

The mechanical response of spherical indentation of superelastic shape memory alloys (SMAs) was theoretically studied in this paper. Firstly, the friction effect was examined. It was found that the friction influence is negligibly small. Secondly, the influence of the elasticity of the indenter was investigated. Numerical results indicate that this influence can not be neglected as long as the indentation depth is not very small. After that, this paper focused on the effect of transformation volume contraction. Our results show that the transformation volume contraction due to forward martensitic transformation can reduce the maximum indentation force and the spherical indentation hardness. These research results enhance our understanding of the spherical indentation responses, including the hardness of the smart material SMAs.

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