A COMPOSITE STRUCTURE FOR LOW-FREQUENCY SOUND ABSORPTION WITH CONTINUOUS BROADBAND UNDER HIGH SOUND PRESSURE EXCITATIONS

High-amplitude sound absorption in the low-frequency range is of great interest because of its vast engineering applications. This work is associated with a novel composite multilayer structure for high-amplitude sound energy attenuation. An analytical model based on the equivalent fluid method by using JCAL (Johnson - Champoux - Allard - Lafarge) model is used to predict the sound absorption performance of the multilayer structure both under 90 dB excitation and 140 dB excitation. Numerical simulation is applied to verify the accuracy of the analytical model. This work demonstrates four samples with different parameters to compare the analytical and numerical results. The results of the two methods agree well with each other. The resonance frequencies of all samples locate in the low-frequency range. It is also found that the resistance of the multilayer structure is enlarged as the sound excitation increases, which can be utilized to design high-intensity sound energy absorbers. The sound absorption coefficient is improved under high sound pressure excitations. To further broaden the sound absorption bandwidth in the low-frequency range, a composite multilayer structure with three absorption units is designed to achieve high-efficiency sound absorption continuously. The composite structures combine the sound absorption performance of each unit and three absorption peaks occur in the low-frequency range. The experiments are performed to verify the sound absorption performance of the proposed structure. The results show that the designed composite multilayer structure has a superior noise reduction capability with continuous bandwidth under high sound pressure excitations in the low-frequency range.