Intelligent Acoustic Structures With Light-Weight Thin Layers Applied To Building Partitions

With the development of modern buildings in the direction of large space and green energy conservation,light-weight thin walls are playing an important role.However,this type of partition wall is light-weight and thin.According to the mass law,sound insulation is coming out,which will contradict the requirements of green energy conservation of building components.In order to solve this problem,this paper attempts to combine the constrained layer damping(CLD)technology and the active structural acoustic control(ASAC)technology.The intelligent structure with light-weight and thin layers are researched and developed in building partitions.This paper has carried out the following research contents:Firstly,the influence mechanism of viscoelastic damping material properties on structural vibration and incident Transmission Loss(TL)is studied numerically in constrained layer damping structures.According to the constitutive model theory of viscoelastic damping materials,the KelvinVoiglt model based on the time-temperature equivalent principle is selected.A finite element model of constrained damping thin layer structure is established.The effects of storage modulus,loss modulus,loss factor and relaxation time on the vibration of thin-layer structures of viscoelastic damping materials are numerically studied.The results show that the effect of viscoelastic materials on the incident transmission loss of constrained layer damping structure does not follow the mass law.The viscoelastic material is similarly glued to the acoustic incident plate and the transmissive plate,so that the two plates vibration in phase.At the same time,the viscoelastic shear deformation can dissipate a large amount of energy transmission from the acoustic incident plate to the transmission plate,which suppresses the vibration of the acoustic transmission plate in the thin composite structure.In addition,the viscoelastic material can shift the incident transmission loss spectrum valley caused by the vibration mode of the thin-layer composite structure to high frequency,and greatly improve the low-frequency sound insulation performance of the structure.Then,a new type of constrained layer damping structure is developed using a cost-effective butyl rubber viscoelastic material.The incident transmission loss characteristics of the constrained layer damping structure are studied numerically and experimentally and the corresponding design method is discussed.The new constrained layer damping structure has the same areal density compared with the composite plate of linear elastic materials.The study shows that the lowfrequency valley of the incident transmission loss spectrum is greatly improved and the improvement is close to 20 dB.Moreover,the incident transmission loss spectrum curve is smoother.At the same time,the more the number of viscoelastic interlayers in the constrained layer damping structure,the more the incident transmission loss spectral valley position will move toward the high frequency.Finally,based on the active structural acoustic control technology,a preliminary system for active constrained damping composite structures applied to building partitions is proposed.The influence of actuator size and position on the incident transmission loss characteristics of active constrained layer damping(ACLD)structure in a single channel system is discussed.The results show that the larger the actuator is,the closer to the geometric center of the acoustic transmission plate,the larger the low-frequency lifting of the transmission spectrum curve and the higher the frequency of the spectral valley position,the better the active control effect.On this basis,increasing the number of viscoelastic interlayers will further significantly improve the mid-high frequency transmission loss performance of the single-channel active constrained layer damping structure.The research in this paper shows that the combination of constrained layer damping and active structural acoustic control technology will provide the possibility to design and develop a new type of light-weight thin intelligent structure with high transmission loss for building partitions.