Ultralight micro-perforated sandwich panel with hierarchical honeycomb core for sound absorption

A theoretical model is developed to study the superior sound absorption performance of ultralight mirco-perforated sandwich panels with double-layer hierarchical honeycomb core. Numerical simulations are performed to validate theoretical model predictions and explore physical mechanisms underlying the sound absorption. Systematic parametric study is implemented to investigate the influence of specific structural parameters on sound absorption. To maximize sound absorption, optimal structural parameters of the hierarchical sandwich are obtained using the method of simulated annealing. It is demonstrated that viscous dissipation of the air inside micro-perforations and around inlet/outlet regions dominates sound absorption. Compared to micro-perforated sandwich panels with regular honeycomb core, not only the proposed hierarchical construction has much improved load-bearing capacity, but also significantly enhanced sound absorption covers a wide range of frequency.