基于切线逼近法的双探头圆拟合裂纹定位方法研究

Research on crack localization based on tangent approximation method with fitting of double probes

针对单探头电磁超声全向导波检测斜向裂纹时因缺陷位置误判致使难以准确定位的问题,提出了一种基于切线逼近法的双探头圆拟合裂纹定位检测方法,以电磁超声换能器检测位置点为圆心,裂纹回波信号的声程为半径,圆拟合获取多个不同位置处的一组圆集合,得到缺陷位置判别的真、伪两条切线;采用双探头数据补偿法得到不同位置处的两组圆集合,通过判别两组圆集合共同的切线为真,从而去除伪切线,实现裂纹的准确定位检测。研究结果表明:双探头圆拟合裂纹定位方法相较于单探头,能有效去除伪切线,裂纹定位最大误差为2.3%,为斜裂纹检测准确定位提供依据。

Addressing the challenge of accurately locating oblique cracks due to misjudgments of defect positions in single-probe electromagnetic ultrasound omni-directional guided wave detection,a two-probe circular fitting crack localization method based on tangent approximation is proposed.This method uses the electromagnetic acoustic transducer(EMAT)detection position point as the center of a circle and the acoustic range of the crack echo signals as the radius.By performing circular fitting at multiple different locations,a set of circle collections is obtained,allowing for the discrimination between true and false defect locations.The double-probe data compensation method is employed to obtain two sets of circles at different locations.By identifying the common tangent line of these two sets of circles,pseudo-tangents are removed,enabling accurate crack positioning and detection.Results show that the dual-probe circular fitting crack localization method effectively eliminates pseudo-tangents compared to the single probe,achieving a maximum crack localization error of 2.3%.This provides a reliable basis for accurate oblique crack detection.