Validated linear dynamic model of electrically-shunted magnetostrictive transducers with application to structural vibration control

Abstract

The performance of magnetostrictive materials, especially those with high initial magnetic permeability and associated low magnetic reluctance, is sensitive to not just the amount of magnetic bias but also how the bias is applied. Terfenol-D and Galfenol have been characterized under constant magnetic field and constant magnetomotive force, which require active control. The application of a magnetic flux bias utilizing permanent magnets allows for robust magnetostrictive systems that require no active control. However, this biasing configuration has not been thoroughly investigated. This study presents flux density versus stress major loops of Terfenol-D and Galfenol at various magnetic flux biases. A new piezomagnetic coefficient d 33 f is defined as the locally-averaged slope of flux density versus stress. Considering the materials alone, the maximum d 33 f is 18.42 T GPa −1 and 19.53 T GPa −1 for Terfenol-D and Galfenol, respectively. Compared with the peak piezomagnetic coefficient d 33 * measured under controlled magnetic fields, the piezomagnetic coefficient d 33 f is 26% and 74% smaller for Terfenol-D and Galfenol, respectively. This study shows that adding parallel magnetic flux paths to lowreluctance magnetostrictive components can partially compensate for the performance loss. With a low carbon steel flux path in parallel to the Galfenol specimen, the maximum d 33 f increased to 28.33 T GPa −1 corresponding to a 45% improvement compared with the case without a flux path. Due to its low magnetic permeability, Terfenol-D does not benefit from the addition of a parallel flux path.

Review of Modeling and Control of Magnetostrictive Actuators

“…As discussed in Section 2, most geometries employed for actuation are rods. Therefore, they can be modeled along the longitudinal axis of the active material, leading to the use of 1D models, or even with linear lumped parameters, as in [23,125,126]. For example, the magnetic field to bias the active material is provided by permanent magnets and a magnetic yoke.…”

Review of magnetostrictive materials for structural vibration control

“…Semi-active smart mounts based on Terfenol-D and Galfenol have been developed for the main rotor gearbox of helicopters, as shown in figure 32. Scheidler and Asnani [92] derived a lumped parameter model and conducted parametric studies for the proposed tunable mount based on linearized constitutive models. The Terfenol-D mount and Galfenol mount were experimentally characterized in [93] and [84], respectively.…”

Characterization of Giant Magnetostrictive Materials Using Three Complex Material Parameters by Particle Swarm Optimization

“…The parameter characterization methods of magnetostrictive materials can be mainly divided into two categories, namely, direct measurement methods and impedance analysis methods [9]. A direct measurement method refers to the method of extracting material parameters from measured hysteresis loops and magnetostrictive curves [10].…”