Analysis of sound transmission through sandwich panels.

Abstract

Due to their advantages over the conventional metal structure, sandwich structures have become used increasingly in transportation vehicles in recent years. However, they have some less favorable properties. In this paper, sound transmission through foam-filled honeycomb sandwich panels was studied using the statistical energy analysis (SEA). Modal density, critical frequency, and the radiation efficiency of sandwich panels were analyzed. The sound transmission loss and radiation efficiency of sandwich panels were predicted theoretically and measured experimentally. The measured results agree with the theoretical predictions quite well. An important observation is that, for foam-filled honeycomb sandwich panels, the radiation efficiency does not decrease to a plateau value at frequencies beyond the critical frequency. Although the high damping helps to improve the sound transmission loss in the critical frequency range, the overall transmission loss of sandwich panels is lower than their heavy metal counterparts. Therefore, the foam-filled honeycomb design must be modified to obtain good noise isolation capability, and a trade-off between the overall stiffness and the sound transmission properties should be considered in the design stage.