Software:
Inversion tool for determining physical parameters of porous materials (ICT_MAA)
n modelling the acoustical behaviour of porous materials, the determination of the physical parameters is a fundamental issue. Because of the difficulties in measuring directly some of these quantities, it is possible to use inverse strategies for calculating them once some acoustical parameters are experimentally known. ICT_MAA is a tool based on a hybrid inversion technique of the Johnson-Champoux-Allard model for the complete calculation of the geometrical quantities from acoustical data. Once the complex acoustical properties have been obtained by using 3Mics_MAA, it is possible to determine airflow resistivity by means of an analytical method and open porosity, tortuosity and viscous and thermal characteristic lengths by using minimization procedure based on genetic algorithm scheme.
Furthermore, Materiacustica offers a simplified version of the inversion tool for the determination of the physical parameters from the surface acoustical parameters obtained according to ISO Standard 10534-2.
Step 1:
Measure surface and characteristic acoustical properties by using 3Mics_MAA.
Step 2:
Determine physical parameters (airflow resistivity, open porosity, tortuosity and viscous and thermal characteristic lengths) by means of ICT_MAA.
Step 3:
It is possible to use the complet set of parameters for calculating complex density and sound velocity of the porous material (by using Johnson-Champoux-Allard model) and applying the equivalent dissipative fluid model in FEM and/or BEM numerical codes.
References
F. Pompoli, P. Bonfiglio, Tecniche avanzate di caratterizzazione fisico-acustica di materiali porosi, ATTI 35° Convegno AIA, Milano 11-13 Giugno 2008.
Documento pdf
P. Bonfiglio , F. Pompoli, Comparison of different inversion techniques for determining physical parameters of porous media, Proceedings of ICA 2007, Madrid September 2-7 2007.
Documento pdf
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