Variation laws of self-magnetic flux leakage signals of high-strength steel wires in bridge cables under coupling effect of corrosion-fatigue loads

To enhance the practicality of magnetic flux leakage detection for high-strength steel wires in bridge cables, the corrosion and stress single factor tests, as well as three-stage interaction tests of prc-corrosion-fatiguc-corrosion and pre-fatigue-corrosion-fatigue were conducted, and the mechanism for the influence of corrosion-fatigue coupling effect on the self-magnetic flux leakage signal was explained. Research results show that the extreme self-magnetic flux leakage signals in the corrosion area increase with the corrosion time, and the variation characteristics are becoming more and more obvious. The maximum variation in the abnormal self-magnetic flux leakage signals caused by the corrosion defect can reach up to 50 000 nT. As the fatigue loading cycle number increases, the self-magnetic flux leakage signal of non-corroded high-strength steels wire is on an overall increasing trend before getting stabilized. When the fatigue loading cycle number exceeds 10 000, the increasing rate of magnetic field intensity decreases and tends to be stable. The alternating stress field applied after the prc-corrosion weakens the self-magnetic flux leakage signal caused by the corrosion defect, and the variation in the magnetic field signal after the second corrosion is related to the degree of prc-corrosion. Under the fatigue load after the pre-corrosion for 9 h, and then in the second corrosion for 3 h, the strength of the self-magnetic flux leakage signal reduces by 32% compared with that in the single corrosion for 12 h. Applying a pre-fatigue alternating stress field can strengthen the magnetic field, leading to an increase in the extreme self-magnetic flux leakage signal after the corrosion. When the pre-fatigue loading cycle number increases from 1 000 to 100 000, the strength of the self-magnetic flux leakage signal increases by 30%. It follows that the abnormal self-magnetic flux leakage signals of high-strength steel wires caused by the initial corrosion can be masked by the fatigue effect, making it difficult to reflect the detection effect of self-magnetic flux leakage of high-strength steel wires by just considering a single factor of variation in the corrosion or stress. Therefore, it is necessary to comprehensively consider the corrosion-fatigue coupling effect, so as to obtain the variation laws of self-magnetic flux leakage signals of high-strength steel wires in bridge cables, thereby providing an analytical basis for the non-destructive test of bridge cables. 3 tabs, 16 figs, 44 refs. © 2024 Chang'an University. All rights reserved.