Low frequency absorption and attenuation of granular aerogel composites

摘要

Aerogel is a material with unique nanoscale properties. In monolithic form aerogel is too costly to be practically used in acoustic applications. Recently a cost-effective technique for producing granular aerogel has been developed, but the acoustic properties of granulated aerogel were not well known. The normal incident acoustic absorption and attenuation of three configurations of granulated aerogel have been determined by means of the transfer function and the transmission matrix methods of measuring normal induct acoustic properties: using the granules as a loose fill, woven into glass fiber blankets, and bound into a solid plate with a poly-vinyl acetate binder. Measurements were conducted using a 64 m impedance tube, the design of which is also discussed.