A pre-screening study of honeycomb sandwich structure filled with green materials for noise reduction

To maximize the potential of the lightweight and high structural performance of composite and to integrate noise reduction function at the same time, the paper reports a noise reduction composite based on honeycomb sandwich structure by filling the honeycomb with different plant and synthetic fibers and utilizing micro-perforated plate (MPP) as the face sheet. The sound-absorbing effect of these structural samples was characterized and compared. The porosity and density of the filler material and the fiber cloth configuration were calculated and measured. The results show that the filling in the honeycomb significantly increases the sound absorption coefficient and widens the sound absorption band. Meanwhile, the MPP parameter determines the peak frequency of the sound absorption curve. Especially in the range of 125 Hz-4000 Hz, cotton and polyester filling provide the highest average sound absorption coefficients of 0.532 and 0.483 among the five materials pre-studied, while the absorption coefficient of the unfilled sample is about 0.15. The results reveal that a filled honeycomb structure with an MPP face sheet can reduce noise while maintaining mechanical properties. The noise-reduction function-integrated structures can potentially influence construction, transportation, and infrastructure as lightweight and space-saving solutions.