Experimental Research On Nondestructive Testing Of Arch Bridge Suspender Based On Magnetostrictive Guided Wave

The arch bridge suspender is an important force transfer structure in the middle and lower bearing arch bridge.In this thesis,combined with the National Natural Science Fund Project "Online Detection Method for Broken Wire Arch Bridge Suspender Corrosion of Magnetostrictive Guided Wave Principle Based on Dynamic Focusing"(NO.61271084),Experimental researchs on nondestructive testing of suspender of arch bridge based on guided waves is carried out.Aimed at the shortcomings of the conventional direction recognition method,a method for identifying the direction of guided wave signals based on time delay estimation algorithm was proposed.The cross-correlation time delay estimation method and LMS adaptive filtering time delay estimation method were introduced into the traditional direction recognition method,which overcame the problems that the ability of direction recognition was affected by the actual wave speed and that the detection frequency was limited by the transducer.Comparative study showed that the direction recognition ability of the proposed method was slightly stronger than the traditional method when the transducer and detection frequency were matched.When the transducer and detection frequency were mismatched,the direction recognition ability of the proposed method is much better than the traditional method.For the detection resolution degradation and signal attenuation problems caused by severe dispersion of guided waves,the basic theory of time reversal focusing technique and its application to the dispersion compensation of the guided wave signals were studied.The simulation results by Abaqus software demonstrated that the application of the time reversal focusing method in the signal dispersion compensation of the guided wave detection signals were feasible.