Effect of fabrication and test conditions on the sensing properties of magnetostrictive composite bolts

Abstract

Bolts are widely used as fasteners because they are easy to remove. When using bolts, it is important for fastening management to monitor the axial force inside the bolt. Magnetostrictive materials are functional materials that have an inverse magnetostrictive effect that causes internal magnetic flux changes due to deformation. In this study, effect of fabrication and test conditions on the sensing properties of magnetostrictive composite bolts were investigated. Magnetostrictive composite bolts were fabricated under various fabricating conditions by combining magnetostrictive material FeCo and epoxy resin. In the experiment, the bolts were fastened to obtain the relationship between the fastening torque, axial strain, and internal magnetic flux change, and the relationship between magnetic flux-density and axial force was compared. In addition, a bias magnetic field was applied during the fastening test to investigate the effect on the sensing characteristics, and the experimental results regarding the relationship between magnetic flux-density and axial force were compared with the theoretical values and the finite element analysis values. Furthermore, Optimal fabrication conditions were considered based on the obtained results.