Deck penetration crack length measurement of orthotropic steel bridge decks based on eddy current detection and its influencing factors
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 ana-lyzed 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 ele-ment simulation.Secondly,the effects of coil parameters and scanning speed on the test are investi-gated.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 scan-ning 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 detec-tion.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.
orthotropic steel bridge decksfatigue crackseddy current detectionlength measure-ment of cracks
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