Equation of state for ferromagnetic transducers

Carl S. Schneider

doi:10.1117/12.475002

11 July 2002 Equation of state for ferromagnetic transducers

Carl S. Schneider

Proceedings Volume 4699, Smart Structures and Materials 2002: Active Materials: Behavior and Mechanics; (2002) https://doi.org/10.1117/12.475002
Event: SPIE's 9th Annual International Symposium on Smart Structures and Materials, 2002, San Diego, California, United States

Abstract

An equation of state based upon magnetization scaled to its saturation value, m equals M/Ms, applied magnetic field scaled to its coercive value, h equals H/Hc, distribution of coercivities, and reversible susceptibility Xrev of magnetization and applied stress, scaled to its initial value is proposed for ferromagnetic transducers. Reversible susceptibility divided by the initial susceptibility is the anisotropy function of domain magnetization, decreasing for Terfenol-D nearly linearly with scaled magnetization from one in the demagnetized state to zero at saturation. Measurements of reversible susceptibility, initial, anhysteretic and saturate magnetization curves, and loops for Terfenol-D show that differential magnetic susceptibility is the product of the reversible susceptibility and a cooperative function due to domain interactions. This function is roughly triangular in magnetization having the same slope from each reversal for magnetization magnitude up to half of saturation, at which the onset and decay of cooperation occur. This cooperative function causes parabolic Rayleigh minor loops and sigmoid major B(H) curves truncated by stress demagnetization. Anhysteretic reluctivity increases linearly with the root sum square of shape and stress demagnetizations, the latter added to the anisotropy function. Magnetization loops under stress are modeled and the d* transducer constant dB/ds is derived as a function of stress and magnetization.

Citation Download Citation

Carl S. Schneider "Equation of state for ferromagnetic transducers", Proc. SPIE 4699, Smart Structures and Materials 2002: Active Materials: Behavior and Mechanics, (11 July 2002); https://doi.org/10.1117/12.475002

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