Wave Based Calculation Methods for Sound-Structure Interaction. Application to Sound Insulation and Sound Radiation of Composite Walls and Floors.

摘要

In building acoustics, reliable prediction methods for sound transmission and sound radiation are required for parameter studies, material selection and optimization studies. Today there is a lack of calculation techniques which can be used in the entire frequency range of interest. Therefore a numerical prediction tool for building acoustical purposes has been developed in this work. It can be used in a broad frequency range to simulate direct sound transmission through finite-sized, composite walls and floors. The model is based on the wave based method for the acoustic domains and a modal approach to describe the structural response. To model multilayered structures consisting of elastic and poro-elastic layers, the wave based method is combined with the transfer matrix method in a new hybrid model. The full room-structure-room description allows reliable predictions in the low-frequency range. The enhanced computational efficiency of the wave based method compared to finite element models allows calculations at higher frequencies. The model is validated with airborne and structure-borne sound insulation measurements and used to investigate the repeatability and reproducibility of sound insulation measurements in the low- and mid-frequency range. Results focus on the influence of finite dimensions on sound transmission loss of composite structures and the relative importance of source and receiving room. Based on the model, the understanding of sound transmission through lightweight double walls and multilayered structures with air layers is improved. Wave based simulations show the importance of cavity absorption and the vibro-acoustic coupling between plate and cavity modes. Furthermore, experiments and simulations have demonstrated that friction and viscous effects have a very significant influence when thin air layers are involved in sound transmission.