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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.Get more news about Bh-sandwich Panel Series,you can vist our website!
Recently, insect-mimicking micro-drones have attracted attention owing to their numerous potential applications. For use as the exoskeletons of these micro-drones, a monolithic sandwich panel with a total thickness of 1 mm was fabricated in this study via a novel technique employing metallic foil with a microlattice core. The face sheets were appropriately designed to be thicker than the foils comprising the core to obtain high failure moments and flexural rigidities. Using this approach, we successfully realized mechanical properties superior to those of the elytra of beetles at a comparable areal density. The mechanical behaviors of the panels were evaluated via theory and finite element analysis (FEA), and the optimal combinations of the two thicknesses of the foils comprising the face sheets and the cores for achieving the maximum strengths for the given areal densities were identified. The sandwich panels are expected to have sufficiently high failure moments and rigidities even with half-height cores, exhibiting great potential for use in insect-mimicking micro-drones.
Insect-mimicking micro-drones have recently attracted considerable research attention owing to their broad range of prospective applications. One of the technical challenges to be addressed for the realization of micro-drones is the development of a novel structure that is ultralight while being sufficiently robust to protect the inner components from impact. For achieving such a structure, a very thin sandwich panel appears to be a rational choice. As an example, Figs. 1(a) and (b) show the elytra of a beetle and its cross section , respectively, revealing the sandwich architecture. We believe that an insect-mimicking drone should have an exoskeleton composed of sandwich panels, similar to the elytra of a beetle.