The Optimal Design Of The Underwater Sound Absorbing Composite Structure

With the rapid development of ship's field,underwater acoustic composite is becoming more and more important.Sound stealth technology of warship plays an important role in its viability.If sound absorption composite material is used as the design material of ship,it can effectively improve its navigation safety.Multifunctional composites have the characteristics of high design,and the development of underwater sound absorption composite materials have broad prospects for the application in the field of ships.Therefore,it is of great significance to study underwater acoustic absorption composite.The main purpose of this paper is to study the sound absorption characteristics of underwater sound ab sorption composites at low frequencies,and to optimize the design of materials and improve their sound absorption properties by the finite element method.Based on the computational acoustics method,the low frequency sound absorption performance of several typical materials structures is simulated and analyzed.These materials mainly include: porous composite materials,sandwich composite structure and so on.The sound absorption coefficient of the material in the standing wave tube is calculated by numerical simulation of the sound absorption performance of the standing wave tube of the underwater acoustic material.The sound absorption coefficient and frequency curve of the material at different frequencies are shown.The underwater sound absorption characteristics of different composites at different frequencies are analyzed and the acoustic optimum design of underwater composite materials and structures is realized.The concrete contents are as follows:Based on the Allard-Johnson model,the acoustic calculation model of porous materials is constructed.The acoustic absorption characteristics of two typical porous sound-absorbing materials,Si C and polyurethane,were studied by simulating the sound absorption performance of the standing wave tube.The results were compared with the related literature.The influence of parameters such as porosity,flow resistivity and tortuosity on the sound absorption performance of the material was studied.The distribution of the sound pressure cloud image of the poro us material at different frequencies was analyzed,indicating the factors affecting the sound absorbing coefficient of porous materials under the underwater low frequency scenario and their changing regulation.According to the calculation of the acoustic method based on finite element theory,constructs the calculation model of a porous material and fiber reinforced composite sandwich structure acoustic composition,study the acoustic characteristics of three different surface sandwich structure under wat er,analyzes the factors influence the sound absorption performance of sandwich structure under water.Finally,the sound absorption coefficients of several kinds of structures under vertical incident acoustic wave are simulated by adjusting the parameter s of sandwich structures.By means of the different sound absorption characteristics of the surface material,the sound-absorbing core material and the layer structure of the material,the optimization scheme of the calculation parameters for improving the sound absorption coefficient of the sandwich structure composite material is given.