Study On Sound Insulation Of Wood Composite Partition Board

Modern wood structure construction was environmentally friendly,sustainable and pollution-free.It not only meets people’s needs for life and buildings,but also can be green,sustainable and renewable.Wood structure construction has attracted more and more attention,and its architectural acoustic environment was particularly important.Therefore,more attention should be paid to acoustic properties of wood composites.In this paper,wood composite material used in wood structure construction was taken as the research object.Plywood,LVL and CLT were used as experimental objects to analyze the sound insulation performance.According to the Biot phenomenon theory model,wood was equivalent to a particular medium,and the relationship of wood parameters including micro and macro structures with the volume elastic modulus of the equivalent medium and the medium density of the wood was respectively explored.Secondly,according to the theory of acoustic wave propagation in laminate,the relationship of the theoretical sound insulation property of wood composite with the volume elastic modulus of the equivalent medium and the density of medium was respectively established.The correlation between the theoretical sound insulation and measured sound insulation was studied and the error of the theoretical model was also analysed.Finally,the sound insulation mechanism and influencing factors of wood composites were analyzed based on the theoretical model.The main conclusions were as follows:(1)Increasing surface density of wood composite has positive effect on its sound insulation property and can effectively restrain the influence of anastomosis(the anastomosis Valley get more shallow).The average sound insulation of PF adhesive plate surface density increased from 2.9kg/m~2 to 7.9kg/m~2 by 4.26dB,and the average sound insulation of UF glued plate surface density increased from 2.9kg/m~2 to 7.9kg/m~2 and the average sound insulation increased6.84dB.With the increase of frequency,the sound insulation of materials increased firstly,then decreased at higher frequency and increased gradually afterwards.This change was related to the critical frequency of material.The high-frequency part of the sound wave was mainly absorbed on the surface of the material,and the low frequency part was absorbed inside the material.With the increase of the surface density,more attenuation of sound wave was obtained inside the material.In contrary,it attenuation decreased on the surface of material.Therefore,when surface density of the material was increased to a certain extent,the effect of surface density on increasing sound insulation of material was not obvious.(2)For the three-ply plywood,the average sound insulation of PF plywood was 4.17 dB higher than that of UF plywood.For the nine-ply plywood,the average sound insulation of PF plywood was 1.07 dB higher than that of UF plywood.Therefore,the effect of adhesive types on the sound insulation performance of the material was not significant with the increment of layers.In the range of material thickness,the variety of adhesive has a positive effect on the sound insulation performance,and the effect is relatively less after a certain range of layers.Therefore,at a certain range of material thickness,the type of adhesive has a positive effect on the sound insulation,and the effect was not obvious after a certain value.(3)As the porosity of wood materials decreased,the density of materials increased,and the flow resistance of airinside the material increased,so the flow resistance rate increased correspondingly.The sound insulation performance of porous materials increased with the increase of flow resistance,but when the flow resistance reached a certain value,the sound insulation performance of porous materials decreased with the increase of flow resistance.If the material density was too small,the interference between acoustic wave and hole will be excessive during the process of sound propagation.The plane sound wave was difficult to enter the interior of the material,and it was reflected directly from the outer surface of the material,so the sound energy can not be converted into heat energy or mechanical energy.This resulted in the reduction of sound insulation.For porous materials,sound insulation performance was not satisfied if the density of material was too large or too small.(4)Under the same thickness and material,the average sound insulation of two different CLT textures is 0.56dB,but for LVL and nine layer plywood,the average sound insulation of the difference is relatively small,so the change of interlayer texture direction has little influence on the sound insulation property of the wood composite.The change of grain for composites led to the change of the elastic modulus,and the modulus of elasticity directly affected the beginning time of critical frequency produced by the bending wave(the frequency for anastomosis effect).So,that is,the frequency section that produces the anastomosis effect.Therefore,the change of grain for composites only has theeffect on the change of the beginning time of anastomosis effect and has no obvious influence on the sound insulation property of the material.