Distributed Stress Measurement in Steel Plates Based on Remnant Magnetization and Magnetoelastic Effect

In this article, we propose a highly consistent and sensitive method for steel plate stress measurement based on strong remnant magnetization and magnetoelastic effect. Firstly, the J-A force-magnetic coupling model is theoretically improved, and the influencing factors of the force-magnetic coupling strength are investigated via parameter sweeping, and it is determined that the magnetization can reduce the initial permeability to improve the sensitivity and consistency of the stress measurement. Then the equation of the coil electromagnetic impedance change in the magnetic circuit versus the stress is deduced, and it is obtained that the stress has a negative linear relationship with the coil impedance, and the sensitivity increases with the increase of the excitation frequency, which is verified by the single-point stress measurement experiment of the sandwich steel plates. Finally, the distributed stress measurement experiments of sandwich steel plates are carried out, which proved that the impedance values at different measurement points after the steel plates are magnetized can successfully reflect the distribution state of the stress. After magnetization, the stress measurement sensitivity of the electromagnetic impedance method increases on average from $0.014 \Omega $ /MPa before magnetization to $0.037 \Omega $ /MPa, with an enhancement of $2.6\times $ . The measurement accuracy under different loads increases on average from 50.699 MPa before magnetization to 7.078 MPa, with an enhancement of $7.2\times $ .