斜拉索表层断丝缺陷漏磁检测圆环阵列传感器

Circular sensor array for surface flaws detection in stay cable based on magnetic flux leakage

针对直径95 mm的斜拉索,建立了三维磁偶极子模型,计算分析了断丝缺陷圆截面的均布磁荷在三维空间形成的漏磁场,重点讨论了单根断丝形成的轴向漏磁场分量在空间的分布规律。构建了轴向漏磁场分量扫查系统,实验验证了模型对单根断丝漏磁场计算结果的准确性。采用-6 d B阈值法确定了轴向漏磁场分量在圆周方向的有效扩散角度约为±6°,以此确定了圆环阵列漏磁传感器的最低阵元数量为30。研制了适用于斜拉索表层断丝缺陷检测的圆环阵列传感器,在提离距离为8 mm的条件下实现了斜拉索表层多处断丝缺陷的扫查成像与定位,并对比分析了阵元数量对成像质量的影响。为研制大直径斜拉索表层缺陷漏磁检测圆环阵列传感器提供了方法借鉴。

Three-dimensional magnetic dipole model is formulated for the stay cable with 95 mm diameter.The magnetic flux leakage field induced by the broken-wire flaw in the 3 D space is analyzed.The spatial distribution of the axial component of the leakage field is highlighted and discussed.Scanning system is constructed to measure the axial component of the leakage field.Experimental results verify the accuracy of the magnetic dipole model on leakage field detection.Threshold method is applied to estimate the effective diffusion angle of the axial component of the leakage field along circumferential direction as±6°,which determines that the minimum number of elements in the sensor array is 30.A circular magnetic flux leakage sensor array is developed for the stay cable.With the lift-off of 8 mm,the sensor array can successfully detect multiple surface broken-wire flaws by providing a scanning image to the cable.The effectiveness of the element number in the array on the quality of the scanning image is discussed.This study provides a reference for designing circular magnetic flux leakage sensor array for surface flaws detection in large-diameter stay cable.