Research On Static And Impact Loads Monitoring Of Plate Structure Based On Distributed Optical Fiber

With the development of the aerospace industry,materials with light weight and good flexibility are widely used on aircraft,thus aircraft get superior flight performance.However,it makes the airframe structure more easily to be damaged when it is subjected to excessive load or impact load,and these injuries influence the proper operation of aircraft.So it is of great significant to obtain static and dynamic loads' information of aircraft's key parts in time for improvement of aircraft structural health monitoring.FBG sensor has such merits,like light mass,small size,as well as anti-electromagnetic interference,so it is very suitable for the health monitoring of aircraft structure.And in view of plate structure is a typic structure of aircraft components,this paper studies the real-time static load and impact monitoring methods for plate structures,the main work includes the following aspects:Firstly,according to the need of static load monitoring for plate structure,a mechanics model of four-sides-fixed plate structure is set up,then studying relationship between FBG sensor amplitude response characteristic and it's influence factors.On this basis,proposing an algorithm of load position and size identification based on the loading angle normalization,realizing the static load recognition.Secondly,for single-ended clamped plate structure impact monitoring,using single-ended clamped wing model builds impact monitoring system of distribute FBG sensors network.By analyzing the impact response signal's time frequency characteristics of each FBG sensor with different impact position,studying the distinction between impact on single-ended clamped plate and impact on common four-sides-fixed plate.Thirdly,impact response signal was processed using Teager Energy Operator,then the method of impact area localization based on dichotomy principle of Time-difference and the method of impact coordinate localization based on Time-difference curve fitting are presented in this paper respectively,which can initially realize the location of impact load.Finally,aiming at the problem of common fiber grating sensor interrogating system with low sampling rate,plate structures with different materials were chosen as monitoring object,using up-sampling(US)theory to make sampling rate conversion,a modification of the generalized cross-correlation(GCC)method with the up-sampling(US)theory is proposed and defined as theUS-GCC method,which can improve the accuracy of the time delay of arrival(TDOA)and impact localization at a low sampling rate.