Research On The Acoustical Radiation Characteristics Of Plate Structure

The plate as a basic structure, has been widely adopted both in the National Defenseareas and the daily life that closely related to us.It not only can be motivated to radiate noiseunder the action,but also can be used to control the spread of noise.Therefore, the study onvibration and sound radiation of the plate structure has not only theoretical significance,butalso has large value of engineering applications.The main work of this theses are:(1)Based on the theory of elastic mechanics and finite element method,combined withMindlin plate theory,this these leads to the relationship between the unit strain anddisplacement, the relationship between the displacement function and evolutions,and therelationship between stress and strain.The paper make a theoretical analysis of the vibrationresponse under different conditions of loads on the plate.Based on the results of vibrationresponse，the article leads to acoustical foundation of the problem of vibration and derivesthe discrete form of the boundary integral equation.(2)Based on the theoretical method of cubic B-spline function to analyze the question ofbending and vibration about the plate.Established boundary element model based on theHelmholtz boundary equation.This article adopt coupled finite element and boundaryelement method based on cubic B-spline function to calculate radiated sound power of therectangular plates in the air,contrast with the calculation results of rectangular plate radiatedsound power using Matlab compiled based on the Rayleigh integral formula,thus to verifythe coupled FEM-BEM method based on cubic B-spline function of precision and accuracyin the calculation of the acoustic power about the plate structure(1)Study the plate parameters following which are influenced on the acoustical radiation characteristics:1)There are five different structural shapes plate: Plate, ribbed plate,trapezoidal plate, triangular plate and trapezoidal plate.2)The layout scheme of ribs onribbed plate.3)20different combinations of boundary constraints.4) The value of thicknesson the plate with the same thickness、the angle of inclination on the plate whose thicknessvaries linearly.5)Different Aspect Ratio.(3)Focus on the problems of consuming time and computing space even incalculable thatare encountered in the calculation of large-scale problems using boundary elementmethod,this paper propose the Fast Multipole Method,which are used as a theoretical basisfor the acoustical radiation calculation of an engine model whose surfaces structure used alot of plate structure, and compare with the calculation using the conventional boundaryelement method.Thus verify the accuracy and efficiency in the calculation of large-scaleproblems using the Fast Multipole Method.