3105 Sound Absorbing Characteristics of Cemented Excelsior Boards(Environmental Engineering)

A sound absorbing metasurface with coupled resonators

An impedance matched surface is able, in principle, to totally absorb the incident sound and yield no reflection, and this is desired in many acoustic applications. Here we demonstrate a design of impedance matched sound absorbing surface with a simple construction. By coupling different resonators and generating a hybrid resonance mode, we designed and fabricated a metasurface that is impedanc...

On measurement of mechanical properties of sound absorbing materials

This paper is an overview of quasistatic measurement technique used to determine mechanical properties of sound absorbing materials. Experimental context and behaviour of polymer foam and rock wool are summarized. Concerning parameters are: static and dynamic strains, dynamic effects such as skeleton resonance and coupling with saturating fluid. Material anisotropy and frequency dependance of c...

3105 Engineering Building “ AUTOMATED ADDITION OF FAULT - TOLERANCE VIA LAZY REPAIR AND GRACEFUL DEGRADATION ”

Bottom-up approach for microstructure optimization of sound absorbing materials.

Results from a numerical study examining micro-/macrorelations linking local geometry parameters to sound absorption properties are presented. For a hexagonal structure of solid fibers, the porosity phi, the thermal characteristic length Lambda('), the static viscous permeability k(0), the tortuosity alpha(infinity), the viscous characteristic length Lambda, and the sound absorption coefficient...

Normalized inverse characterization of sound absorbing rigid porous media.

This paper presents a methodology for the inverse characterization of sound absorbing rigid porous media, based on standard measurements of the surface acoustic impedance of a porous sample. The model parameters need to be normalized to have a robust identification procedure which fits the model-predicted impedance curves with the measured ones. Such a normalization provides a substitute set of...