Microstructure design of lightweight fibrous material acting as a layered damper for a vibrating stiff panel.

Based on the idea that a layer of properly designed and manufactured fibrous material can serve as both a sound absorber and a structural damper, an approach is introduced in this article to design the microstructure of a fibrous layer for it to provide optimal damping performance. To begin with, previous work related to structural damping by fibrous layers was reviewed. Then the most appropriate models from the literature were adapted for use in the current study. A system comprising an aluminum panel and a limp fibrous layer was driven by a line force, and both the spatial velocity response of the panel and the power distribution within the system were calculated to quantify the degree of damping provided by the fibrous layer, which helped identify the airflow resistivity that provides optimal damping for any frequency and panel of interest. Given the optimal airflow resistivity, a model relating fiber microstructure to airflow resistivity was used to infer the optimal microstructure required to achieve the optimal damping performance. One finding of the current work, for example, was that as the target frequency was reduced, the fiber size required to achieve the optimal damping performance increased.