Structural design and performance control of membrane-cavity structural metamaterials with partitioned chambers for low-frequency broadband sound absorption

In view of the problems of large thickness and low efficiency of traditional materials in low-frequency noise control, this research proposes a high-performance broadband sound-absorbing metamaterial for the frequency band of 600–700 Hz based on the membrane-cavity structural (MCS) metamaterial. Through combining the theoretical modeling, finite element simulation, parameter optimization, and experimental verification, a systematic approach to improve the performance of the MCS metamaterial is proposed. First, a theoretical model of the membrane-cavity coupling system was established to reveal the influence of geometric parameters on sound absorption characteristics. On this basis, an integrated preparation method based on fused deposition modeling was proposed, and the multi-unit double-layer membrane-cavity structural (MDL-MCS) metamaterial with a rigid membrane as core was successfully prepared, which effectively overcome the problems associated with controlling the tension and achieving consistent assembly of traditional flexible membranes. To improve design efficiency, whale optimization algorithm was employed to automatically optimize the depth of each chamber in the MDL-MCS metamaterial, and an excellent configuration with high average sound absorption coefficient in the target frequency band was obtained. The most significant findings of this work are summarized as follows: the optimized structure achieves an average sound absorption coefficient exceeding 0.95 in the 600–700 Hz band, with a subwavelength thickness of only λ/11.4 at 600 Hz, demonstrating excellent broadband absorption and deep subwavelength performance. Experimental results validate the design, showing good agreement with simulations. This study provides an effective strategy for designing compact, high-efficiency acoustic metamaterials for low-frequency noise control.