Theoretical and experimental study on optimum operational conditions of a magnetostrictive force sensor

Abstract

Terfenol-D, as a giant magnetostrictive material, is used to fabricate different force sensors. In these sensors, bias magnetic field and mechanical pre-stress are applied to improve the sensor’s characteristics. The present paper proposes the optimum values of the above operational conditions to reach maximum sensitivity and linear measuring of the sensor. Initially, a sensor’s model based on coupled piezomagnetic equations is developed and affective parameters on the output voltage are recognized. An experimental setup is fabricated and used to obtain magnetization and magnetostriction curves of Terfenol-D at different mechanical pre-stresses to study the parameters. Analyzing the experimental curves, the sensor's effective parameters, including magnetostriction constant, magnetic permeability, and their variation with axial stress, are calculated and imported to the model. Hence, the sensor's sensitivity and linear measuring range are obtained at different values of bias magnetic field and mechanical pre-stress and optimum values considering the external force’s amplitude are introduced. The maximum sensitivity factor is 0.004515 mV/Ns−1 which obtained at mechanical pre-stress of 6.89 MPa and bias magnetic field of 25kA/m. In these conditions the linear measuring range of the sensor is 260–500 N. To validate the model, the results are compared with previously reported experimental results, and the minor errors show the precision of the model and experimental investigation.