钢桥面板顶板贯穿裂纹长度涡流检测及其影响因素

Deck penetration crack length measurement of orthotropic steel bridge decks based on eddy current detection and its influencing factors

针对正交异性钢桥面板顶板贯穿型疲劳裂纹隐蔽性强、难以精确检测的问题,提出通过涡流检测方法对裂纹长度进行测量。首先,对试验获取的涡流检测信号进行分析,探究信号特征与裂纹长度之间的关系,据此拟合出裂纹长度的测量公式,并通过有限元模拟对其有效性进行验证;其次,研究线圈参数与扫查速度对检测效果的影响;最后,通过有限元模拟分析了水平裂纹相邻顶点间距、裂纹与线圈中心的偏移距离、裂纹与线圈扫查方向的夹角对检测结果的影响。结果表明:增加圆柱形线圈外径与内径之比并适当减小线圈内阻可提高检测灵敏度;裂纹长度的测量值随着线圈扫查速度的增大而减小;水平裂纹相邻顶点间距越大,越利于精确测量裂纹长度;随着裂纹与线圈中心偏移距离的增加,检测信号的变化幅值逐渐减小,裂纹长度测量值也随之下降;此外,线圈扫查方向与裂纹长度方向的夹角越大,越不利于检测。该钢桥面板疲劳裂纹长度涡流检测方法可实现高效、便捷、精准的无接触式检测,为钢桥的运营维护提供相关技术参考。

Aiming at the problem that the penetration fatigue cracks of orthotropic steel bridge decks are hidden and difficult to be detected accurately,the eddy current detection method is proposed to measure the length of the cracks.Firstly,the signals obtained from eddy current detection are analyzed to investigate the relationship between the signal characteristics and crack length,according to which the measurement formula of crack length is fitted,and the validity is verified by finite element simulation.Secondly,the effects of coil parameters and scanning speed on the test are investigated.Finally,the effects of distance between adjacent vertices of two horizontal cracks,the offset distance between the cracks and the center of coil,and the angle between the direction of coil scanning and crack on the test results are analyzed by finite element simulation.The results show that the detection sensitivity can be improved by increasing the ratio of outer diameter to inner diameter of cylindrical coil and decreasing the inner resistance of coil appropriately.The measured value of crack length decreases with the increase of the coil scanning speed.The larger the distance between adjacent vertices of two horizontal cracks,the more accurate for measuring the crack length.The amplitude of the detection signal decreases with the increase of the disance between the crack and the center of the coil,and the measured value of crack length also decreases.Furthermore,the greater the angle between the direction of coil scanning and crack,the less accurate it is for detection.With high detection accuracy,the eddy current detection method for measuring fatigue crack length of steel bridge decks proposed in this paper can achieve efficient,convenient,and accurate non-contact detection,which provides a technical reference for the operation and maintenance of steel bridges.