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Physical-Phenomenological Constitutive Modeling and Numerical Analysis of Magnetic Shape Memory Alloys

Mousavi, Mohammad Reza | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48676 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Arghavani, Jamal; Sohrabpour, Saeed; Naghdabadi, Reza
  7. Abstract:
  8. Magnetic shape memory alloys (MSMAs) are a new class of smart materials that exhibit characteristics of large recoverable strains and high frequency. These unique characteristics, make MSMAs interesting materials for applications such as actuators, sensors, and energy harvesters. This thesis presents a three-dimensional phenomenological constitutive model for MSMAs, developed within the framework of irreversible continuum thermodynamics. To this end, a proper set of internal variables is introduced to reflect the microstructural consequences on the material macroscopic behavior. Moreover, a stress-dependent thermodynamic force threshold needed for variant reorientation is introduced which improves the model accuracy. Preassumed kinetic equations for magnetic domain volume fractions, decoupled equations for magnetization unit vectors and appropriate presentation of the limit function for martensite variant reorientation lead to a simple formulation of the proposed constitutive model. To show the model capability in reproducing the main features of MSMAs, several numerical examples are solved and compared with available experimental data as well as available three-dimensional constitutive models in the literature. Demonstrating good agreement with experimental data besides possessing computational advantages, the proposed constitutive model can be used for analysis of MSMA-based smart structures. Furthermore, the deformation of a MSMA thin-walled cylinder under magneto-mechanical loadings is simulated by the proposed constitutive model. Accordingly, a cylindrical microactuator is designed and some applications are proposed. The simulation results show that for a thin-walled cylinder with thickness of 200 μm, radius of 3 mm and length of 20 mm, increasing the magnetic field up to about 0.6 Tesla, induces a decrease of 900 μm in length and an increase of 130 μm in radius
  9. Keywords:
  10. Magnetic Shape Memory Alloys (MSMA) ; Three Dimensional Modeling ; Hardening ; Internal Variable ; Magneto-Mechanical Loading ; Cylindrical Microactuator

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