Study On Damage Detection In Wing Cover Structure Based On Lamb Wave

In modern society, structural health monitoring system is widely used in aircraft, bridge,offshore platforms and large and complex structures. The Lamb wave based structural damageddetection technology plays a very important role in structural health monitoring system.This study adopts active detection technique based on Lamb Wave to monitor damage incomposite materials. The suitable excitation signal be loaded by the sensors pasted on thestructure surface. The excitation signal propagation in structure, by comparative analysis andpattern processing response signals collected before and after damage happens, the damagelocation can be determined. Through symmetrical load and calculate percentage of damage tojudge the stiffened damage locations and degree.The main works are showed as follows:Firstly, the propagation characteristics of Lamb wave in composite structure are discussed.According to the phase velocity and group velocity dispersion curve, the optimal centralfrequency is studied in the range of selective frequency.Secondly, judge and analysis the propagation velocity of composite before and after damagehappens, according to the arrival time of the Lamb wave group velocity. The damage locationswere judged by the elliptical location method. In this paper, the damage location is judged fornarrow plate, square plate, curved plate and stiffened plate respectively.Finally, the damage degree of stiffened plate was judged by different damage reflectance;the corresponding relationship between damage degree and damage reflectance be establish bycalculation results.The difference signals were calculated by eliminating common information of pre and postdynamic response signals. Damage location and degree be judged by time of fly and attenuationcoefficient of wave packet peak according to difference signals. The results show that large andcomplex structure can be rapidly detected by the technical research on global damage detecttechnology based on Lamb wave.