Low-frequency sound absorption of microperforated panel composite plate-type acoustic metamaterial

Microperforated panel composite plate-type acoustic metamaterial structure is proposed for the low-frequency sound absorption problem of a single-layer microperforated panel.The plate-type acoustic metamaterial is placed inside the cavity behind the microperforted panel.The experimental results show that the sound absorption performance of the composite structure is better than single-layer microperforated panel under the same cavity thickness.The sound absorption curve of the composite structure is greater than 0.6 from 396 Hz to 892 Hz,and the sound absorption coefficient is 0.972 at 453 Hz.The composite structure is simulated by the finite element method.The sound absorption curve of the simulation is basically consistent with the trend of the experimental sound absorption curve.The low-frequency sound absorption is mainly contributed by interaction of the plate-type acoustic metamaterial and sound waves.At the corresponding frequency of the sound absorption peak value of the plate-type acoustic metamaterial,the effective dynamic mass density of plate-type acoustic metamaterial begins to become negative.Microperforated panel and platetype acoustic metamaterial have mutual coupling effects inside the composite structure.The coupling causes a slight offset in the first peak of the composite structure.Increasing the mass weight of the plate-type acoustic metamaterial can cause the first sound absorption peak to move to the low-frequency.And increasing the thickness of the sub-cavity of the plate-type acoustic metamaterial,and keeping the thickness of the total cavity,the first sound absorption peak can also be moved to the low frequency.