A Study On Parameters Of Statistical Energy Analysis Of Laminated Panels Based On Spectral Finite Element Method

Laminated plate structure has many advantages,such as high strength,light weight,fatigue resistance and good design ability.Such structure has been widely used in aircrafts,ships and automobiles.High speed aircraft is subjected to complicated and harsh environment such as aerodynamic heat,broadband frequency noise and strong vibration during the flight process.The effect of noise excitation can cause fatigue damage of the laminate structure on the aircraft.The thermal load will lead to the decrease of the bearing capacity of the material,and then influence the reliability of the aircraft.Therefore,the thermal acoustic vibration response of the plate structure must be considered during the design stage of aircraft.In general,the problem of broadband acoustic vibration coupling is divided into low,middle and high frequency bands.The high frequency section is generally modeled by the statistical energy analysis(SEA),however,it is difficult to obtain the statistical energy analysis parameters for general laminated plates.In view of the above background,a method based on the spectral element method(SFEM)is established i to obtain the statistical energy analysis parameters of laminated plates in this dissertation,and the thermal effect on statistical energy analysis parameters is considered.The main contents of the dissertation are as follows:1.Establishment of the wave number calculation method based on the spectral element method(SFEM).Three nodes spectral finite elements are used in the thickness direction of laminates,and the characteristic equation of wavenumber is established by using the plate's stiffness and mass matrices.The wave mode classification based on the Pearson correlation coefficient method is used to specify the mode groups,and the dispersion characteristics of wave are obtained.The validity of the proposed SFEM-based algorithm is confirmed by comparing the calculated results with the experimental values or other theoretical values by simulating homogeneous thin plates,sandwich plates and orthotropic laminates.SFEM is more applicable than sandwich plate theory and more accurate than the wavenumber calculation result of laminated plate theory.2.SEA parameters and sound transmission loss of laminate are calculated based on SFEM.The modal density,radiation impedance and sound transmission loss of the sandwich plate are calculated based on the SFEM.The accuracy of the SFEM calculation of the SEA parameters is verified by comparison with the results of related literatures.The total coupling loss factor of laminates with viscoelastic layers is calculated based on the SFEM.The accuracy of the total internal loss factor calculated by SFEM is verified by comparison with the results of related literatures and the VA one software.SFEM has the characteristics of good accuracy,wide application and small calculation amount,and it is very effective for the statistical energy analysis modeling of general laminated plates.3.The laminate SFEM laminate formulation considering thermal effect is derived,and the effect of thermal effect on the wavenumber and SEA parameters of sandwich panel is investigated.Thermal strain energy is introduced into elastic potential energy,and the correction expression of thermal stress to unit stiffness in SFEM is derived,then a SFEM laminated plate modeling method considering thermal effect is established.The thermal effects on the wavenumbers,statistical energy analysis parameters and sound transmission loss of laminated plates are investigated.