A potential substitute for traditional micro-perforated panels.

What is it about?

This absorber proposed in this study is called Micro-Grooved-Element (MGE) and it is based on the presence of internal micro-channels generated when the element is assembled. Despite the necessity of having two layers, it is possible to have a certain control of the weight because the layers are provided with wide slots. The MGE offers the advantage of requiring basic manufacturing process (typically milling), instead of the less cost effective laser cut used for MPE. Moreover, it is possible to easily manufacture MGE with micro-apertures which are smaller in cross section and length than in case of traditional MPE, while still preserving adequate porosity. This results in higher performance in terms of absorption coefficient in both linear and non-linear regimes.

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Why is it important?

This study shows that the MGEs can provide high absorption coefficient while requiring basic manufacturing process. Tests performed in absence of mean flow demonstrate that MGEs can be used as potential substitute for traditional micro-perforated elements at least in room acoustic applications. The small dimensions of the inner channels included in the MGE sample (depth 0.085mm and length 0.200mm) and the porosity 1.72% are responsible for the high acoustic performance. Remarkably, in terms of absorption coefficient, tests have shown an advantage from 10 to 150% of the micro-grooved over the micro-perforated samples. A semi-empirical formulation has been used for transitional and non-linear regimes.