Optimal ultra-broadband sound-absorption performance design for coiled up space structures with nonlinear robustness

In this paper, based on a highsound-pressure microperforated plate model, a nonlinear sound-absorption model for multi-unit couplings based on coiled-up space structures is proposed. The sound absorption performance and relative impedance of two-unit coupled structures (TUCSs) were studied. The results show that the TUCS sound- absorption performance, which is good at low sound pressures, decreases significantly as the incident sound pressure increases owing to impedance mismatch. Furthermore, the influence of parameters such as aperture size, plate thickness, perforation rate, and equivalent length on the unit's structural sound-absorption performance was studied. By employing the particle swarm optimization algorithm, we optimized the parameters of an eight-unit coupled structure (EUCS) using the proposed model. The optimization results reveal the nonlinear robust sound-absorption characteristics of the structure, which means the EUCS can maintain a stable and good sound-absorption performance when the incident sound pressure level and frequency are within 125-155 dB and 400-3000 Hz, respectively. Experimental assessments of the EUCS sound-absorption performance within the 300-1900 Hz range confirmed the accuracy of the proposed model and the efficacy of the optimized sound- absorption capabilities of the structure. Consequently, the proposed model and sound-absorption structure demonstrated potential applications in the acoustic lining design of aircraft engines.