不同提离值对TMR传感器漏磁检测的影响OA

In order to investigate the effects of lift-off value and magnetic pole spacing on the magnetic flux leakage detection performance of TMR(tunnel magnetoresistance)sensors,assess the applicability of the planar dipole model,and evaluate the feasibility of defect size inversion,experiments were conducted on ferromagnetic specimens containing rectangular artificial defects.The lift-off value is precisely controlled by the TMR probe,which is incrementally adjusted in 1 mm steps across a range of 1～10 mm.This adjustment is implemented via a motion control platform configured for fixed-length measurements.Concurrently,the magnetization unit delivers a stable,fully saturated magnetic field.The experimental data were analyzed using MATLAB software,assuming a magnetic pole spacing of 25 mm.Subsequently,a grid-type defect detection test was performed under controlled conditions,specifically with a lift-off value of 3 mm and a magnetic pole spacing of 25 mm.The results indicate that the TMR detection signal exhibits nonlinear attenuation with respect to the increase of lift-off value.Within the tested range of 1～10 mm,this attenuation behavior can be segmented into three regions(low,medium,and high)characterized by average signal attenuation magnitudes of approximately 67%,27%,and 6%,respectively.Reducing magnetic pole spacing enhances signal amplitude but concurrently increases susceptibility to electromagnetic noise;thus,smaller magnetic pole spacings yield measurable benefits only under low lift-off conditions.The planar dipole model fitting parameters exhibit high accuracy,and the corresponding computational results demonstrate excellent agreement with experimental measurements.Furthermore,the grid-based detection method enables precise quantification of defect dimensions,including length and width with a comparatively minimal measurement error.These findings demonstrate that the TMR sensor exhibits high sensitivity and reliability in detecting rectangular defects.Lift-off value and magnetic pole spacing are identified as the two primary parameters governing detection performance.Moreover,the planar dipole model can be applied to defect detection analysis,providing theoretical and experimental support for practical defect detection.