On the sensitivity of the design of composite sound absorbing structures

The acoustic properties of composite structures made of a perforated panel, an air gap, and a porous layer, can be studied numerically by a combined use of ad hoc optimization and sensitivity analysis methods. The methodology is briefly described and is systematically applied to a series of multi-layer configurations under manufacturing constraints. We specifically consider a foam layer of constant thickness presenting three different degrees of reticulations (pore opening). For each foam layer, the optimal geometrical parameters of the perforated panel and the cavity depth maximizing sound absorption under normal incidence are determined, together with the corresponding sensitivity indices. The simulation results are found in good agreement with interpretations and experimental data provided elsewhere. From a general perspective, the framework can be used to identify the most influential parameters within multiscale settings for acoustics studies, hence enabling robust design under material and microstructural uncertainties for instance.