Kresling-Inspired Acoustic Metamaterial with Reconfigurable Property and Tunable Sound Absorption

This study proposes a decagonal Kresling origami-based acoustic metamaterial, termed DKOAM, for tunable low-frequency sound absorption. The proposed structure uses a decagonal Kresling-folded cavity as the reconfigurable backing cavity of a Helmholtz-type resonator. It combines it with neck-impedance regulation to improve the tunable absorption bandwidth. The folded cavity height can be adjusted by reconfiguring the Kresling structure, thereby regulating the equivalent acoustic volume, cavity compliance, and impedance-matching condition. A conventional transfer-matrix formulation is employed as an analytical tool to describe the geometric–acoustic coupling among the folded cavity height, equivalent acoustic volume, perforation ratio, neck impedance, input impedance, and absorption coefficient. Finite element simulations and impedance-tube measurements are conducted at representative folded-cavity heights to validate the theoretical prediction. By combining prototype validation with numerical design-window analysis of the multi-aperture configuration, the effective absorption response (α > 0.8) can cover 166–708 Hz. The single-hole configuration provides an effective absorption range of 166–315 Hz, while the multi-hole configuration extends the effective absorption range to 305–708 Hz through distributed neck impedance and improved impedance matching; at the lowest-frequency state, the sample thickness is only approximately 1/49 λ. These results indicate that the proposed DKOAM provides a feasible structural strategy for tunable low-frequency sound absorption via decagonal Kresling-folded-cavity reconfiguration and multi-aperture neck-impedance regulation.