Measurements of loss factors of honeycomb sandwich structures

Loss factor measurements were performed on different sandwich panels to determine the effects of different skin and core materials on the acoustical properties of sandwich structures. The study included the following panel/beam designs: glass-epoxy skin with a meta-aramid (m-aramid) core, glass-epoxy skin with a para-aramid core, carbon skin with a m-aramid core, and a carbon skin with a m-aramid core of subsonic wave speed. The loss factors were calculated for all the above configurations. Analysis of the results revealed that panels constructed with carbon fiber skins exhibited larger loss factors than glass fiber skins. Panels designed to achieve a subsonic wave speed did not show a significant increase in loss factor above the coincidence frequency. The para-aramid core had a larger loss factor value than the meta-aramid core. The data indicated that judicious choice of sandwich materials can lead to reductions in noise transmission.