Improved acoustic performance simulation for hollow brick walls
Abstract
This study aims at improving the prediction of the sound transmission loss performance of fired clay hollow brick walls, with or without a thermal lining, using a finite-size transfer matrix method (FTMM). The hollow brick layer is described as a thick, homogeneous, anisotropic plate. The physical properties of the equivalent material are obtained by means a static homogenization process based on a finite element method. This initial step considers a variable horizontal offset between successive rows of bricks and the frequency range of the specific Lamb mode behavior, driven by the stiffness of the wall thickness. Therefore, a range of values is obtained for each of the elastic parameters of the anisotropic material. Then, these variation ranges are used as boundary conditions for an automatic model fitting based on a genetic algorithm coupled to the FTMM prediction tool. Then, the model of the brick wall is used in new predictions on a large scope of brick geometries including also different types of thermal linings. The presence of mortar dabs distributed over the wall surface is accounted for by means of an analytical approach developed in previous work and implemented in the prediction tool. Measurement and prediction results are presented in terms of sound reduction index of the bare walls and sound reduction index improvement of the linings.
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