Research In The Vibration Response Of The Thin Wall Composite Structure Under Random Acoustic Loading

This paper studied the vibration response calculation and analysis of the thin wall composite structure under random acoustic loading. This is the basis of researching the problem of the thin wall composite structure sonic fatigue problem.This paper is based on the study of theory and methods. Firstly, this paper use of the Miles single degree of freedom theory which assumes that the fundamental frequency response of structure is principal, the large deflection nonlinear forced vibration differential equation of the laminated composite plates subjected to random acoustic excitation are derived, in this differential equation transverse shear is considered. Secondly, in order to derive the nonlinear mode equation of the laminated composite plate , we use the improved of Garlerkin method. For sloving the mode equation, the equivalence linearization method is adopted to linearize the mode equation, The statistic characteristics of the displacement response are obtained by using the input and output relations of a linear system, Then, the responses of stress and strain are derived. Finally the calculation programmes are writed by using Matlab and the estimation of the displacement and stress response of a laminated composite plate under acoustic load are realized. Calculations of displacement and stress response of a laminated composite plate with different material anisotropy, different acoustic load, different edge conditions and different fibre orientation angles are accomplished, Then, mean-square response with transverse shear and no transverse shear by small deflection theory and large deflection theory are calculated, and the characteristic of mean-square response are compared and analyzed with different acoustic load, The statistic characteristics of mean-square response of laminated composite plate with different theory is compared.The simulation methods presented in this thesis for calculating the vibrational response of aircraft laminated composite plate structure in an elevated thermal environment and the calculated results are of great values to analyze and solve the sonic fatigue problem and improve the structure dynamic strength.