Research Of Impact Monitoring Based On Multiple Fiber Optical Sensing Technology

In the aircraft and spacecraft service,low velocity impact load causes aerospace structural damage often exhibit strong concealment,and over time,these injuries often cause structural failure,which will seriously affect the safety and reliability of aerospace vehicle.Therefore,it is very important to judge the position of the low velocity impact load in time and accurately.Fiber optic sensor has many advantages,such as light weight,flexibility,electromagnetic interference,high sensitivity,and convenient for distributed networking.It is very suitable for applying in increasingly complex aircraft service environment.Therefore,the impact load localization method based on the principles of FBG and distributed optical fiber sensing are studied in this paper.The main work includes the following aspects:First,a method for extracting impulse response eigenvalues based on fractal filtering and wavelet packet energy extraction is proposed,and a fiber FBG sensor cellular layout is proposed.On this basis,the impact monitoring of aluminum alloy plate structure is realized by combining the impact positioning algorithm of polynomial fitting.Secondly,the composite plate and clamped aluminum alloy plate structure are used as the research object,aiming at the accuracy requirements of impact localization.Then study optical fiber FBG sensor impulse response characteristics,and put forward a corresponding two dimensional Gauss distribution fitting method,combined with the Newton iterative method to realize the accurate localization of the impact load.Thirdly,the principle of Sagnac sensing is studied,and the Sagnac interferometric sensing system is constructed.On this basis,the response characteristics of fiber Sagnac sensing probe are studied,and the traditional Sagnac sensor probe is improved.A ring fiber Sagnac sensing probe is proposed.This ring probe is applied to the impact monitoring research of aluminum alloy plate structure,and the effective location of the impact load is realized by the time difference method.Finally,the principle of the ?-OTDR sensing technology is studied,and the system structure and the impact positioning algorithm for impact monitoring are put forward.A ?-OTDR monitoring system is built,and the application of ?-OTDR sensing technology in shock load monitoring is preliminarily studied by using LabVIEW and MATLAB programming.