scholarly journals Constitutive modelling of magnetic shape memory alloys with discrete and continuous symmetries

2014 ◽  
Vol 470 (2169) ◽  
pp. 20140216 ◽  
Author(s):  
K. Haldar ◽  
D. C. Lagoudas
Keyword(s):  
Free Energy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Evolution Equations ◽  
Internal State ◽  
Polycrystalline Materials ◽  
State Variables ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Internal State Variables

A free energy-based constitutive formulation is considered for magnetic shape memory alloys. Internal state variables are introduced whose evolution describes the transition from reference state to the deformed and transformed one. We impose material symmetry restrictions on the Gibbs free energy and on the evolution equations of the internal state variables. Discrete symmetry is considered for single crystals, whereas continuous symmetry is considered for polycrystalline materials.

The effect of heat treatments on Ni43Mn42Co4Sn11 meta-magnetic shape memory alloys for magnetic refrigeration

2014 ◽  
Vol 74 ◽  
pp. 66-84 ◽  
Author(s):  
Nickolaus M. Bruno ◽  
Cengiz Yegin ◽  
Ibrahim Karaman ◽  
Jing-Han Chen ◽  
Joseph H. Ross ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Magnetic Refrigeration ◽  
Heat Treatments ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys

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.

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