Calculation And Analysis Of Cavity In Sound Insulation Layer Based On Sound Absorbing Material

Sound waves are often used in sonar systems to detect and classify targets.Underwater sound absorbing materials are widely used in modern submarines because they can absorb sound energy and control sound propagation path,so as to reduce the intensity of acoustic target and improve the acoustic stealth performance of submarines.In order to minimize the reflection and transmission of sound wave energy and absorb sound wave energy as much as possible,it is necessary to study the structure and material characteristics of sound absorbing materials.Because the acoustic properties of sound-absorbing materials are greatly affected by frequency,temperature and pressure,it is necessary to carry out in-depth research on their acoustic properties before underwater applications are selected.In this paper,by establishing the numerical simulation model of acoustic material structure,using the acoustic software LMS Virtual.LAB,two-point impedance tube method and three-point standing wave tube method are used to simulate the acoustic characteristics of the acoustic structure with a cavity.The effects of the cavity structure form and material mechanical parameters on the sound absorption and insulation performance of the acoustic material are discussed.The main contents of this paper are as follows:(1)The research status,achievements and progress of acoustic materials at home and abroad are summarized,and the main research contents of this paper are introduced.(2)Based on the basic theory of acoustics and using transfer matrix method,the sound absorption characteristics of uniform composite flat-panel sound-absorbing materials and non-uniform composite flat-panel sound-absorbing materials are theoretically deduced.(3)The concept and processing method of finite element analysis are elaborated.The parametric geometric modeling function of Rhinoceros software is introduced.The large geometric models of acoustic materials with different cavity structures are established by using Rhinoceros software.Two kinds of simulation methods,two-point impedance tube method and three-point standing wave tube method,are theoretically deduced and simulated.(4)The geometric model was defined and meshed by ANSYS software.The relationship between the change of sound absorption performance and elastic modulus,density and loss factor was compared by simulation.(5)The sound absorption properties of several common cavity structures are analyzed,and the sound insulation properties of the material layer with good influence factors of sound absorption coefficient are qualitatively analyzed.(6)Summarized the main points of this study and the prospects for future research.