Research On Low Velocity Impact Load Localization For Aircraft Structures

The aeronautical aircrafts are inevitably subject to load of impacts with different forms andenergy in service. These impacts could reduce the structural strength, threatening the aircraft safetyseriously. Therefore, it is necessary to platform real-time and on-line structural health monitoring ofimpact. Moreover, identifying the location of impact load is the most basic problem of impactmonitoring.With the engineering need mentioned above, the main contents are as follows:Firstly, the theories of acoustic emission technology were summarized, then the procedure toobtain the time of arrival (TOA) based on wavelet transform was emphatically analyzed; Secondly,several localization algorithms such as time arriving, signal synthesis imaging method based on timereversal focusing and imaging method based on cross correlation function were studied. The on-lineimpact location monitoring system was also built based on the requirements. Experiments onadvanced composite grid structures and the model of trailing edge had been done to validate thesealgorithms. Thirdly, by comparing the experimental results, the advantages and disadvantages of theabove algorithms were outlined. Finally, a new algorithm combining a Newton’s method with anunconstrained optimization was proposed. To validate this method, experimental location testingwas conducted on the above structures. The results showed that the proposed algorithms wasconvergent from almost any guess point and does not require a priori knowledge of the group velocityof Lamb waves as well as the mechanical properties. The source location was achieved withsatisfactory accuracy (the maximum error in estimation of the impact location was less than1cm),requiring little computational time (nearly2s).