Research On The Sound Absorption And Insulation Performance Of Sandwich Structures Based On Three-periodic Minimal Surface

As one of the environmental pollution,noise pollution has caused great harm to human beings.The effective means to control noise is to block or absorb the noise in the process of transmission.As a lightweight multifunctional composite structure,sandwich structure has the characteristics of heat dissipation,impact resistance,vibration,and noise reduction,and is widely used in aerospace,rail transit and other fields.Using Triply Periodic Minimal Surface(TPMS)as the core layer of sandwich structure can greatly improve the design efficiency and acoustic performance.Selective laser melting(SLM)-based TPMS sandwich structure can achieve precise control of structure type and porosity.At present,the research of TPMS sandwich structure mainly focuses on statics and dynamics,but there are few researches on sound absorption and insulation performance.Based on this,this paper studied the sound insulation and sound absorption performance of the three-period minimal curved sandwich structure under acoustic excitation by combining simulation and experiment,and improved its sound absorption performance through structural optimization design.The main research contents and conclusions are as follows:Firstly,a typical implicit curved skeleton-like and lamellar Gyroid porous structure was designed based on MATLAB parametric programming with reference to the key parameters affecting the sound absorption and insulation performance of traditional sandwich structures.The influences of volume fraction,panel thickness,cell layer number and macro structure type on the acoustic insulation performance of TPMS sandwich structure were investigated by numerical simulation and experimental research.The results show that the transfer loss of TPMS sandwich structure increases with the increase of panel thickness,cell layer number and volume fraction.With other conditions unchanged,the sound insulation performance of skeleton-like TPMS sandwich structure is better than that of lamellar structure,especially when the frequency is above 2500 Hz,but the sound insulation performance of medium-low frequency TPMS sandwich structure is lower than lamellar structure.Secondly,acoustic simulation software was used to establish the acoustic model of TPMS sandwich structure to calculate the acoustic absorption coefficient in the range of 450Hz-6400 Hz.The Ti6Al4 V sandwich structure was formed by laser selective melting technology,and the acoustic absorption coefficient test of all structures was completed in the acoustic impedance tube to verify the correctness of the finite element analysis.The influence of different microstructure parameters on the sound absorption performance of TPMS sandwich structure is analyzed.Finally,the concrete performance of two TPMS macro structures in the application of sound absorption is compared comprehensively.The results show that in the range of 450-6400 Hz,the skeleton-shaped TPMS sandwich structure has better acoustic absorption performance than lamellar structure,and the maximum acoustic absorption coefficient exists when the number of cell layers is 1C.The thickness of the panel has great influence on the sound absorption performance.The core volume fraction will increase with the tortuous factor τ,but there is a maximum value.Finally,in order to further improve the sound absorption performance of TPMS sandwich structure,based on the theory of micro-perforated plate,the TPMS sandwich structure with micro-holes in the panel,through the acoustic-electrical analogy method to establish the theoretical model of micro-perforated plate TPMS sandwich structure,using the simulation software to calculate the maximum coefficient of resonance,and in the acoustic impedance tube test system for verification.Finally,the influence of the structural parameters of TPMS sandwich on its sound absorption performance is analyzed comprehensively under the condition that the number,size and location of micropores are fixed.The results show that compared with TPMS sandwich structure,the design of micro-perforated plate greatly improves the sound absorption performance of the sandwich structure: the maximum sound absorption coefficient of skeleton-shaped TPMS sandwich structure of micro-perforated plate is higher than 0.9,and the maximum sound absorption coefficient of lamellar sandwich structure is higher than 0.8.The resonant frequency decreases with the increase of the thickness of the panel and the number of cell layers.The peak value of sound absorption coefficient increases with the increase of volume fraction and panel thickness.Within 450-6400 Hz,when the number of cell layers increases to a certain extent,the high-order resonance frequency will appear.