Constitutive Modeling of Magneto-Thermo-Mechanical Response of Field-Induced Phase Transformations in NiMnCoIn Magnetic Shape Memory Alloys

2010 ◽  
Author(s):  
Krishnendu Haldar ◽  
Dimitris C. Lagoudas ◽  
Burak Basaran ◽  
Ibrahim Karaman
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Constitutive Modeling ◽  
Mechanical Response ◽  
Temperature Phase ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Model Predictions ◽  
Working Principle ◽  
The Magnetic Field

In this work we model the magnetic field induced phase transformation (FIPT) of magnetic shape memory alloys (MS-MAs). The working principle of such materials is described by the cross coupling of mechanical, thermal and magnetic fields. The Thermo-magneto-mechanical constitutive equations are derived in a thermodynamic consistent way. A 3-D stress-field-temperature phase diagram is constructed using the model. The model is calibrated from the experimental data and the model predictions are compared with experimental results.

Constitutive Modeling of Magnetic Field-Induced Phase Transformation in NiMnCoIn Magnetic Shape Memory Alloys

2009 ◽  
Author(s):  
Dimitris C. Lagoudas ◽  
Krishnendu Haldar ◽  
Burak Basaran ◽  
Ibrahim Karaman
Keyword(s):  
Magnetic Field ◽  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Constitutive Modeling ◽  
Model Calibration ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Working Principle ◽  
The Magnetic Field

In this work we model the magnetic field induced phase transformation (FIPT) of magnetic shape memory alloys (MSMAs). The working principle of such materials is described by the deformation of continua due to mechanical and magnetic forces. The cross coupling of mechanical and magnetic variables is captured by introducing nonlinear kinematics. The mechanical and magnetic constitutive equations are derived by a thermodynamic consistent way. Finally, the model prediction followed by model calibration is compared with the experimental results.

Effects of Surface Pinning, Locking and Adaption of Twins on the Performance of Magnetic Shape-Memory Alloys

2011 ◽  
Vol 684 ◽  
pp. 177-201 ◽  
Author(s):  
Markus Chmielus ◽  
Peter Müllner
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Surface Damage ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Fatigue Lifetime ◽  
Twin Density ◽  
External Constraints ◽  
The Magnetic Field

We study the effect of surface modifications and constraints on the mechanical properties of Ni-Mn- Ga single crystals, which are imposed by (i) structural modifications near the surface, (ii) mounting to a solid surface, and (iii) guiding the stroke. Spark eroded samples were electropolished and characterized before and after each polishing treatment. Surface damage was then produced with spark erosion and abrasive wearing. Surface damage stabilizes and pins a dense twin-microstructure and prevents twins from coarsening. The density of twins increases with increasing degree of surface deformation. Twinning stress and hardening rate during mechanical loading increase with increasing surface damage and twin density. In contrast, when a damaged surface layer is removed, twinning stresses, hardening rate, and twin density decrease. Constraining the sample by mounting and guiding reduces the magnetic-field-induced strain by locking twins at the constrained surfaces. . For single-domain crystals and for hard magnetic shape-memory alloys, external constraints strongly reduce the magnetic-field-induced strain and the fatigue lifetime is short. In contrast, for selfaccommodated martensite and for soft magnetic shape-memory alloys, the twin-microstructure adapts well to external constraints and the fatigue lifetime is long. The performance of devices with MSMA transducers requires managing stress distributions through design and control of surface properties, microstructure, and constraints.

Hysteresis effects in the magnetic-field-induced reverse martensitic transition in magnetic shape-memory alloys

2010 ◽  
Vol 108 (4) ◽  
pp. 043914 ◽  
Author(s):  
Thorsten Krenke ◽  
Seda Aksoy ◽  
Eyüp Duman ◽  
Mehmet Acet ◽  
Xavier Moya ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensitic Transition ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
The Magnetic Field

Experiments and Modeling of the Magneto-Mechanical Response of Magnetic Shape Memory Alloys

2009 ◽  
Author(s):  
Heidi P. Feigenbaum ◽  
Constantin Ciocanel
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Constant Magnetic Field ◽  
Mechanical Response ◽  
Magnetic Flux Density ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Power Harvesting ◽  
Axial Compressive Stress

Magnetic shape memory alloys (MSMAs) are relatively new materials that exhibit a magnetic shape memory effect as a result of the rearrangement of martensitic variants under the influence of magnetic fields. Due to the MSMAs newness there is limited understanding of their magneto-mechanical behavior. This work presents experimental and modeling results of MSMAs for cases in which the material is loaded and unloaded in uniaxial compression in the presence of a constant magnetic field. The experiments are performed with the magnetic field applied perpendicular and at an angle to the mechanical loading axis. During the loading and unloading process, the evolution of the magnetic flux density is monitored to assess the potential of these materials for power harvesting applications. The modeling is based on the thermodynamic approach proposed by Kiefer and Lagoudas [1]. This model was modified and calibrated to reproduce material response under biaxial constant magnetic field and variable uni-axial compressive stress. Comparing the experimental and simulated results, one can recognize that further work is needed to improve the model.

A Full Two-Dimensional Thermodynamic-Based Model for Magnetic Shape Memory Alloys

2014 ◽  
Vol 81 (6) ◽  
Author(s):  
Douglas H. LaMaster ◽  
Heidi P. Feigenbaum ◽  
Isaac D. Nelson ◽  
Constantin Ciocanel
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Magnetization Vector ◽  
Unit Cell ◽  
Experimental Results ◽  
Two Dimensional ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Short Side ◽  
Model Predictions

Magnetic shape memory alloys (MSMAs) are interesting materials because they exhibit considerable recoverable strain (up to 10%) and fast response time (higher than 1 kHz). MSMAs are comprised of martensitic variants with tetragonal unit cells and a magnetization vector that is innately aligned approximately to the short side of the unit cell. These variants reorient either to align the magnetization vector with an applied magnetic field or to align the short side of the unit cell with an applied compressive stress. This reorientation leads to a mechanical strain and an overall change in the material's magnetization, allowing MSMAs to be used as actuators, sensors, and power harvesters. This paper presents a phenomenological thermodynamic-based model able to predict the response of an MSMA to any two-dimensional (2D) magneto-mechanical loading. The model presented here is more physical and less empirical than other models in the literature, requiring only three model parameters to be calibrated from experimental results. In addition, this model includes evolution rules for the magnetic domain volume fractions and the angle of rotation of the magnetization vectors based on thermodynamic requirements. The resulting model is calibrated using a single, relatively simple experiment. Model predictions are compared with experimental data from a wide variety of 2D magneto-mechanical load cases. Overall, model predictions correlate well with experimental results. Additionally, methods for calibrating demagnetization factors from empirical data are discussed, and results indicate that using calibrated demagnetization factors can improve model predictions compared with the same model using closed-form demagnetization factors.

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