scholarly journals Room temperature magnetic shape-memory effect in strontium-doped lanthanum cobaltite single crystals

AIP Advances ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 095217
Author(s):  
A. Yokosuka ◽  
H. Kumagai ◽  
M. Fukuda ◽  
K. Ando ◽  
Y. Hara ◽  
...  
Keyword(s):  
Shape Memory ◽  
Single Crystals ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Room Temperature ◽  
Magnetic Shape Memory ◽  
Lanthanum Cobaltite

Modeling and FEM Simulation of Shape Memory Microactuators

2008 ◽  
Vol 583 ◽  
pp. 229-256 ◽  
Author(s):  
Berthold Krevet ◽  
Manfred Kohl
Keyword(s):  
Shape Memory ◽  
Single Crystals ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Performance Prediction ◽  
Fem Simulation ◽  
Phenomenological Approach ◽  
Polycrystalline Materials ◽  
Magnetic Shape Memory ◽  
Insight Into

This article reports on two models for the shape memory effect and explains, how they are implemented in a finite element method program. The first model uses a phenomenological approach. For the example of a microgripper, the performance prediction of real actuators made of polycrystalline materials is demonstrated. In the second model, the martensite-austenite phase transition is treated as a thermodynamically activated process. Thermodynamic laws, like e.g. the minimization of the Gibbs free energy, are used for the formulation. To simplify the model, it is primarily intended to describe the behavior of single crystals. By comparing the simulated bending characteristic of a cantilever beam with experimental data, the applicability to polycrystalline material is tested. Due to the physics based formulation, this model gives more insight into the structural processes involved. This is very useful, e.g., for physical extensions needed for the simulation of the magnetic shape memory effect. It is shown, how the model can be extended to predict the behavior of actuators made of ferromagnetic Ni-Mn-Ga single crystals in a magnetic field.

High performance shape memory effect in nitinol wire for actuators with increased operating temperature range

2014 ◽  
Vol 07 (05) ◽  
pp. 1450063 ◽  
Author(s):  
Riccardo Casati ◽  
Carlo Alberto Biffi ◽  
Maurizio Vedani ◽  
Ausonio Tuissi
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
High Performance ◽  
Room Temperature ◽  
Operating Temperature ◽  
Niti Wire ◽  
Shape Memory Actuators ◽  
Nitinol Wire ◽  
Operating Temperature Range

In this research, the high performance shape memory effect (HP-SME) is experimented on a shape memory NiTi wire, with austenite finish temperature higher than room temperature. The HP-SME consists in the thermal cycling of stress induced martensite and it allows achieving mechanical work higher than that produced by conventional shape memory actuators based on the heating/cooling of detwinned martensite. The Nitinol wire was able to recover about 5.5% of deformation under a stress of 600 MPa and to withstand about 5000 cycles before failure. HP-SME path increased the operating temperature of the shape memory actuator wire. Functioning temperatures higher than 100°C was reached.

Cold Bending a Ni-Ti Shape Memory Alloy Wire

2015 ◽  
Vol 661 ◽  
pp. 98-104 ◽  
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.

scholarly journals Temperature Dependence of Pseudoelasticity and Shape Memory Effect in Fe3Ga Single Crystals with D03 Structure

2008 ◽  
Vol 48 (7) ◽  
pp. 1014-1019 ◽  
Author(s):  
Hiroyuki Y. Yasuda ◽  
Kouki Fukushima ◽  
Mitsuhiro Aoki ◽  
Yukichi Umakoshi
Keyword(s):  
Shape Memory ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Shape Memory Effect ◽  
Memory Effect
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