Research On Vibration And Sound Transmission Characteristics Of Sandwich Composite

Nowadays,lightweight and stealth play a significant role in improving the combat ability of modern naval ship.Composite material has been widely used in automobile industry,ship and ocean engineering,aerospace industry,etc.due to its much more merits of high strength,stiffness,resistance to electrochemical corrosion and outstanding design ability.Besides the conventional bearing loads,the composite structures are usually exposed to noisy environment under special work environment.Therefore,the research on dynamic and sound transmission characteristics of these new material structures is of great value.Based on first order shear theory,the finite element analysis equations of laminate plate are derived and the calculating programs are written in FORTRAN language.The vibration responses are calculated in time and frequency domain respectively.The formulas of equivalent mechanical parameters for honeycomb core are deduced base upon Y style periodic cell and the accuracy of each equivalent simulation methods are also compared.With the help of Virtual.Lab Acoustics,the acoustic performance of a honeycomb sandwich panel is investigated in this paper and the influence of several parameters on STL are analyzed as well.The subjects of this study are composite laminated and aluminum honeycomb sandwich panels which were analyzed from the perspective of mechanics and acoustics.For laminated panels,displacement responses,stress distribution and natural mode are discussed under static loading.Forced vibration responses were analyzed with the methods of Wilson-? and transfer functions.Because of the discontinuity of honeycomb sandwich plates,the accuracy of three equivalent theories are discussed.They are static equivalent,dynamic equivalent,and the sandwich theories.Finally,to obtain the sound pressure distribution,level difference and transmission loss,acoustic software Virtual.Lab Acoustics is also used in the processing of the acoustic performance calculation.On this basis,the previous model is used to analyze the influence of several parameters on STL,including the face thickness and density,the height of core,the wall thickness and the length of honeycomb systematically.