| With the increase in car ownership,vehicle noise has become a major impact on people`s working and living environment.The vehicle interior noise is getting more and more attention from consumers because it has a certain impact on the physical and mental health of the drivers and passengers.As a kind of sound package material,polyurethane(PU)porous materials can reduce the interior noise and improve the ride comfort.Meanwhile,greening and high efficiency are the basic requirements for the development of automotive materials.Therefore,the development of environmentally friendly PU porous materials has important theoretical significance and engineering practical value.From the perspective of environmental protection,the PU porous material was prepared by using soybean oil polyol(SOP)in this paper.The contents of four raw materials(SOP,polyisocyanate,silicon oil and blowing agent)in the synthetic formula were analyzed.The experimental was designed by the Response Surface Method(RSM),the sample was synthesized by one-step polymerization.Through the measurement and analysis of the acoustic properties,compression properties and microstructure of the samples,it was found that the difference in the contents of the raw materials influences their properties.Among them,the blowing agent contents have a significant influence on the acoustic properties of the soybean oil PU porous material.In order to improve the acoustic properties of the soybean oil PU porous matieral.The average sound absorption coefficient and average sound insulation coefficient were taken as the optimization objectives.The approximation models between the four raw materials contents and two optimization objectives were established by RSM.Then,the optimal raw material ratio was obtained by multi-objective particle swarm optimization algorithm.The results showed that 35 g SOP,44.18 g polyisocyanate,1.53 g silicon oil and 1 g blowing agent are advantageous for sound absorption and insulation performances at the same time.In order to analyze the influence of the microstructure of porous materials on the sound absorption performance,this paper analyzed the morphological of the PU porous material and assumed the porous material was composed of a plurality of tetrakaidecahedrons.The periodic units with different microstructure dimensions(strut length,pore diameter)and pore characteristics(shape,number)were established.The porosity,air-flow resistivity,tortuosity,viscous characteristic length and thermal characteristic length of the porous materials were obtained through the flow simulation.And the sound absorption performance was predicted by Jhonson-Champoux-Allard(JCA)acoustic model.The results showed that the sound absorption performance of porous materials is improved with the increase of the strut length and pore number.The increase of the pore diameter is beneficial to the improvement of the sound absorption performance.However,the excessive pore diameter will also lead to the performance declining.And the pore shape has a small effect on the sound sbaorption performance.The Statistical Energy Analysis(SEA)model of the firewall and front floor were established based on the SEA method.The soybean oil PU porous material was applied to the sound package of the SEA model,respectively.The effects of soybean oil PU porous materials on the acoustic properties of the firewall and front floor sound package were simulated.The results showed that the sound absorption performance of the sound package using soybean oil PU porous material is improved in the range of 400~800 Hz and 3150~4000 Hz,the sound insulation performance is improved in the range of 2000~4000 Hz.It means that the environment-friendly soybean oil PU porous material has a certain improvement effect on the vehicle interior noise. |
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