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Proceedings Paper

Reversible strain in Ni-Mn-Ga with collinear field and stress
Author(s): LeAnn E. Faidley; Marcelo J. Dapino; Gregory N. Washington; Thomas A. Lograsso
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Paper Abstract

Our previous work on ferromagnetic shape memory Ni50Mn28.7Ga21.3 demonstrates reversible compressive strains of -4100 microstrain along the [001] direction under the application of a magnetic field also along the [001] direction with no external orthogonal restoring force. The reversibility of the strains is due to internal bias stresses oriented orthogonal to the field. These results show promise for the use of Ni-Mn-Ga as the core material in solenoid transducers. In this paper, the reversible strains are explained by considering pinning sites as the source of the internal bias stresses in the material. Following prior work by Kiefer and Lagoudas, a phenomenological model is constructed for the motion of twin variants in the presence of an orthogonal pair formed by a magnetic field and an internal bias stress. The model is formulated by considering the Zeeman, elastic, and pinning energies, from which an appropriate Gibbs energy function is constructed. Minimization of the Gibbs function then yields a constitutive model for the strain. The accuracy of this model is studied and its implementation as a hysteresis kernel in homogenization theories is discussed.

Paper Details

Date Published: 16 May 2005
PDF: 12 pages
Proc. SPIE 5761, Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, (16 May 2005); doi: 10.1117/12.600210
Show Author Affiliations
LeAnn E. Faidley, The Ohio State Univ. (United States)
Marcelo J. Dapino, The Ohio State Univ. (United States)
Gregory N. Washington, The Ohio State Univ. (United States)
Thomas A. Lograsso, U. S. Dept. of Energy (United States)
Iowa State Univ. (United States)

Published in SPIE Proceedings Vol. 5761:
Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics
William D. Armstrong, Editor(s)

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