Research on crack monitoring technology of flexible eddy current array sensor based on TMR sensors

Abstract

The TMR (Tunnel MagnetoResistance) sensors are used to replace the original induction coils, and the TMR sensors are arrayed along the x-axis direction, which quantitatively monitor crack propagation through the response sequence of TMR sensors. Firstly, a current dipole model is proposed to characterize the influence of disturbed magnetic induction intensity at the test point, and the method of quantitative monitoring of subsurface crack is proposed. Then, the finite element model of the sensor is established to analyze the disturbed effect of crack propagation on eddy current with different excitation frequencies. Finally, the experiments on the surface and subsurface crack monitoring with different depths are carried out. The experimental results show that the crack propagation can be monitored quantitatively through the response sequence of the TMR sensors. Also, the effect of subsurface crack monitoring can be improved by increasing the longitudinal distance between the test point and the crack (LDTC).