Research On Structural Health Monitoring For Wing Box Under Random Excitation

Structural health monitoring system is now mainly used in various industries such as aerospace, civil engineering, offshore platforms and other large complex structures, and is gradually used in the national products. In the research of aircraft structural health monitoring, the online structural health monitoring under the natural excitation has important practical application value. The main research subject of this thesis is to guarantee the on-line real-time data transmission, and to set up a complete structural health monitoring system, and to achieve the function of damage detection.Based on the random vibration theory and pseudo excitation method, the numerical simulation extracted the random excitation spectrum in the flight environment of wing box; with the vibration displacement modal data which extracted from the finite modal analysis,the correlation function amplitude vector assurance criterion is adopted to determine the damage degree; finally, the research of the structural health monitoring system has been demonstrated to be valid and stable.The main works are showed as follows:Firstly, this thesis discusses the damage detection theory based on the random vibration, and the common data processing method in the damage detection, analyses the principle of characteristic parameters in damage detection. Based on the displacement modal date and the modal assurance criterion, the correlation function amplitude vector assurance criterion is adopted as the characteristic parameters.Secondly, the importance of natural environment excitation method is introduced in detail. In order to extract the natural environment excitation of wing-box in flight, the numerical simulation is done through the technique of CFD.Thirdly, the pseudo excitation method is introduced in detail. The dynamics model of a composite wing-box is established by finite element analysis software ANSYS. The displacement modal matrix are gained by PSD analysis on the base of modal analysis. Finally, the correlation function amplitude vector assurance criterion is adopted to determine the damage degree. The relative changes between the CorVs of the intact and damaged structure are used together with a statistic evaluation formula to be the important part of damage detection. The correlation function amplitude vector assurance criterion is adopted to determine the damage degree and location. In addition, in order to improve the visualization and easy use of the damage detection method, optimization software is developed by using GUI of MATLAB.It clearly indicate that the optimization result shows the damage situation of the wing-box, so the validity and stability of the proposed statistic detection approach in the flight structural health monitoring are demonstrated to be right.