Experimental and numerical investigations on acoustic damping of monoclinic crystalline wideband sound absorbing structures

In order to overcome the limitations of traditional microperforated plate with narrow sound absorption bandwidth and a single structure, two multi-cavity composite sound-absorbing materials were designed based on the shape of monoclinic crystals: uniaxial oblique structure (UOS) and biaxial oblique structure (BOS). Through finite element simulation and experimental research, the theoretical models of UOS and BOS were verified, and their sound absorption mechanisms were revealed. At the same time, the influence of multi-cavity composites on sound absorption performance was analyzed based on the theoretical model, and the influence of structural parameters on sound absorption performance was discussed. The research results show that, in the range of 100–2000 Hz, UOS has three sound absorption peaks and BOS has five sound absorption peaks. The frequency range of the half-absorption bandwidth (α>0.5) of UOS and BOS increases by 242% and 229%, respectively. Compared with traditional microperforated sound-absorbing structures, the series and parallel hybrid methods significantly increase the sound-absorbing bandwidth of the sound-absorbing structure. This research has guiding significance for noise control and has broad application prospects in the fields of transportation, construction, and mechanical design.