Acoustic Characters Study on the Influence of Micro-Fillings in Underwater Sandwich Composite Structure

Sandwich composite is a new structure of acoustic stealth structure, implementing both loading and acoustic stealth. Micro-fillings can improve the sandwich absorption coefficient. The influence parameters are studied by absorption theories analysis of sandwich structure. The absorption and reflection coefficient in different categories, size and layers of fillings are analyzed by pulse tube experiments. The results shows that the first absorption peak moves to low frequency by adding fillings, the peak frequency are lower when the fillings size increase, and the absorption coefficient are higher when the thickness of sandwich layers are closed.