Microstructural modelling of acoustic dissipation in porous materials
PhD student: Eva Lundberg (leave of absence since 2016, continued in 2020)
Multilayer panels, as used in vehicle floors, walls and roofs must be designed to fulfil many requirements, including acoustic and structural demands derived from global requirements. In order to maintain or increase the acoustic performance with reduced weight, porous materials are often used as a part of the panels. The acoustic and elastic properties of the open cell foams are determined by their micro geometry, but are traditionally characterised from measurements on macro-level of a sample of a porous material. The macro level properties are interdependent since they are all related to the actual micro structure. Thus, to design the macro level acoustic properties for a required performance, physically relevant models linking these to the micro structure would be necessary.The main scope of the present work, is to model the micro-structure as an idealized, periodic structure, allowing anisotropic properties on the micro-scale using a long wavelength assumption. From simplified analytical descriptions of the acoustic parameters and their dependence on the micro-structure properties, the microstructural properties can then be linked to averaged macroscopic properties.