Design and numerical analysis of syntactic hybrid foam for superior sound absorption

Abstract

A microcellular polyurethane (PU) foam is widely used as a sound absorber to eliminate noise by utilizing its complex internal structure. The most intriguing issue for the sound absorbing PU foam is how to reduce density while maintaining or improving the performance. In this study, novel syntactic hybrid foams (SHFs) were designed and suggested by embedding hollow microbeads in the open cell PU foam. Numerical simulation was carried out to predict sound absorbing performance by employing periodic unit cells representing microstructures of a bare foam (BF) and SHFs. It was found from the simulation that the sound damping performance of SHFs was improved significantly by a detoured sound propagating path provoked by the embedded microbeads. The predicted sound absorption performance of SHFs was even superior to that of the bare foam with double density. Furthermore, heat transfer and structural analysis showed that SHFs can provide high thermal insulation and mechanical robustness. It is anticipated that the hybrid microstructure designed in this study will be utilized to develop advanced sound absorbing materials with outstanding sound absorption, thermal insulation, and mechanical stiffness.