Characterization of giant magnetostrictive materials under static stress: influence of loading boundary conditions

Abstract

Giant magnetostrictive materials (GMM) can be integrated in actuator or sensor applications. The design of these systems is optimized based on a good knowledge of the material properties and conditions of use. Terfenol-D exhibits the greatest room temperature strain among commercially available GMM, however, its magneto-elastic behavior is very sensitive to prestress level. In this work, the design of an experimental setup dedicated to the characterization of GMM magneto-mechanical behavior under constant stress is described. A major difficulty is to master the mechanical boundary conditions while the sample is subjected to dynamic magnetic loading. The dynamic stress experienced by the sample is connected to the magnitude of the magnetostriction strain, the stiffness of the sample and the stiffness of the characterization setup. Results show that an appropriate setup is able to reduce the dynamic stress variations induced by magnetic excitation variations below 0.1 MPa, while this dynamic stress can reach up to 20 times the magnitude of the applied stress when the control system is not used. With the boundary conditions being controlled, magnetic and magnetostrictive behavior of Terfenol-D are characterized under various uniaxial compressive stress levels, from the stress-free conditions to 90 MPa. By comparing the results obtained under controlled and non-controlled stress conditions, it is shown that uncontrolled boundary conditions can be responsible for errors of several percent on the magnetic induction measurement. The measurement of strain is even more sensitive to the boundary conditions, with errors up to 40% and 30% on the longitudinal and transverse strains, respectively. This work highlights the utmost importance to control the boundary conditions in order to characterize the magneto-mechanical behavior of GMM.

Twisting and Reverse Magnetic Field Effects on Energy Conversion of Magnetostrictive Wire Metal Matrix Composites

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Dynamic Anti-plane Behavior of Rare Earth Giant Magnetostrictive Medium With a Circular Cavity Defect in Semi-space

“…ih z e ih z ik w w (12) In order to discuss the magnetic potential corresponding to the reflected wave, according to the governing equation (8), the magnetic potential function corresponding to the reflected wave can be expressed as:…”

“…Dwivedi [7] proposed Walker's type trial function and numerical illustration method to investigate the dynamic property of transverse domain walls in bilayer piezoelectro-magnetostrictive nanostructures. Domenjoud [8] designed an experimental set up to study the effect of load boundary conditions on the properties of giant magnetostrictive materials.…”

Anhysteretic Magneto-Elastic Behaviour of Terfenol-D: Experiments, Multiscale Modelling and Analytical Formulas

“…In a first part, the anhysteretic magneto-elastic behaviour of Terfenol-D is characterised. Particular attention is given to the experimental boundary conditions since a lack of control can lead to measurements errors of up to 40% on the longitudinal strain [ 37 ]. An energy-based multiscale approach [ 23 ] is then briefly presented and applied to Terfenol-D.…”