Microstructure influence on acoustical properties of multi-scale porous materials

Venegas Castillo, RG

Abstract

This thesis investigates the microstructure influence on the acoustical properties of
multi-scale porous materials. The theory of sound propagation in multi-scale materials
is extended to account for physical processes specific to very small pores, e.g.
rarefaction and sorption effects. First, models of sound propagation through single
porosity fibrous and granular materials are investigated. These are then extended to
account for fibre and particle porosity respectively. A first approach to modelling the
acoustical properties of triple and quadruple porosity materials is then introduced. An
investigation of the acoustical properties of resonant absorbers backed with multiscale
porous materials follows. Finally, a description of two practical applications is
presented. The models introduced in this thesis are validated by performing sound
absorption coefficient and sound transmission loss measurements. Accurate
predictions are obtained provided that the material microstructure is adequately
described and the multi-scale physics involved is accounted for. It is concluded that
the material microstructure has a significant influence on the acoustical properties of
multi-scale materials. Furthermore, these materials exhibit greater sound absorption
and sound transmission loss at reduced weight compared with conventional single
porosity materials with similar mesoscopic characteristics and the same layer
thickness. The findings of this thesis could provide a basis for designing or finding
new porous materials with tailored acoustical properties.

Citation

Venegas Castillo, R. Microstructure influence on acoustical properties of multi-scale porous materials. (Thesis). Salford : University of Salford

• Thesis Type: Thesis
• Deposit Date: Oct 3, 2012
• Award Date: Jan 1, 2011