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Proceedings Paper

A continuum thermodynamics formulation for micro-magneto-mechanics with applications to ferromagnetic shape memory alloys: application to domain wall-twin boundary dissociation
Author(s): Chad M. Landis
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Paper Abstract

A continuum thermodynamics formulation for micromagnetics coupled with mechanics is devised to model the evolution of magnetic domain and martensite twin structures in ferromagnetic shape memory alloys. The theory falls into the class of phase-field or diffuse-interface modeling approaches. In addition to the standard mechanical and magnetic balance laws, a two sets of micro-forces their associated balance laws are postulated, one set for the magnetization order parameter and one set for the martensite order parameter. The second law of thermodynamics is analyzed to identify the appropriate material constitutive relationships. The general formulation does not constrain the magnitude of the magnetization to be constant, allowing for the possibilities of spontaneous magnetization changes associated with strain and temperature. The equations governing the evolution of the magnetization are shown to reduce to the commonly accepted Landau-Lifshitz-Gilbert equations when the magnetization magnitude is constant. Numerical solutions to the governing equations are presented to investigate the fundamental interactions between the magnetic domain wall and the martensite twin boundary in ferromagnetic shape memory alloys. Calculations are performed to determine under what conditions the magnetic domain wall and the martensite twin boundary can be dissociated, resulting in a limit to the actuating strength of the material.

Paper Details

Date Published: 2 April 2008
PDF: 8 pages
Proc. SPIE 6929, Behavior and Mechanics of Multifunctional and Composite Materials 2008, 69291O (2 April 2008); doi: 10.1117/12.782708
Show Author Affiliations
Chad M. Landis, The Univ. of Texas at Austin (United States)


Published in SPIE Proceedings Vol. 6929:
Behavior and Mechanics of Multifunctional and Composite Materials 2008
Marcelo J. Dapino; Zoubeida Ounaies, Editor(s)

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