Study On Acoustic Emission Localization And Time Difference Estimation Algorithm For Structural Damage

At present,the traditional damage detection technology of structural parts,such as ray detection and electromagnetic detection technology,cannot realize the integral dynamic state monitoring.While the acoustic emission(AE)is a kind of nondestructive testing technology with high sensitivity based on the principle of elastic wave detection,which can effectively perceive the early damage and fault of structural parts.Combined with the principle of time difference,the multi-sensor elastic wave sensing makes it possible to realize the overall damage monitoring technology of structural parts.The time difference location technology of damage source of structural parts is one of the key technologies for damage monitoring of integral structural parts.Nowadays,the time difference algorithm is mainly divided into two categories: direct method and indirect method.Although threshold technique and region estimation technique are simple,the accuracy of time difference is low.The location algorithm is mainly divided into the region localization method and the time difference localization method.Due to the limitation of the time difference accuracy,only the location estimation of the damage source can be completed,and the positioning accuracy is low.Therefore,it is a key problem to obtain the high precision time difference of multi-sensor fusion and the algorithm to locate the whole damage of structure.In this thesis,the time difference estimation algorithm of damage response correlation interval based on acoustic emission technology and the least square damage localization algorithm of structural parts are proposed,which can obtain accurate time difference and realize the localization of damage source of whole structure.The main research contents of this thesis are as follows:(1)Research on damage response time difference estimation of structural parts.The acoustic emission test platform based on the long aluminum plate structure was designed and built to collect the acoustic emission signal generated by broken lead.The characteristics of acoustic emission signals were analyzed,and a time difference estimation algorithm based on correlation interval was proposed based on correlation interval,and the factors affecting the accuracy of time difference estimation method were studied.The error analysis of the calculated time difference results under different sensor spacing shows that the algorithm has high accuracy.(2)Research on damage localization of structural parts.An acoustic emission test platform based on steel structural parts was designed and built to collect the acoustic emission signals generated by broken lead and measure the propagation velocity of acoustic emission waves in the steel structural parts.Based on the time difference,a damage localization algorithm of structural parts based on least squares is deduced.The damage localization experiment of structural parts is designed,and the error analysis of the localization results calculated at different lead breakage points is carried out.The results show that the proposed algorithm has high accuracy.(3)Writing damage location software for structural parts.Based on the Matlab2021 A development platform,the proposed time difference estimation algorithm based on the correlation interval and the least square damage localization algorithm of structural parts are programmed into the software interface.