Hybrid rod-plate lattice metamaterial with broadband vibration attenuation

Abstract

Based on the manufacturing advantages and design freedom of additive manufacturing, the control of elastic waves in metamaterials can be realized through the design of the unit cell. In this paper, a new design approach for 3D acoustic metamaterials consisting of rods and chiral plates (RCPM) was proposed, which displays omnidirectional low-frequency bandgaps over the irreducible Brillouin zone. The vibration modes at the boundary of the bandgaps were analyzed to illustrate the generation mechanism of the bandgaps. A spring-mass system and a clamped- clamped beam were developed to get the modes of the first bandgap boundaries. The influences of the main geometry parameters on the bandgaps were discussed systematically based on numerical simulation and theoretical formula, which demonstrates that the bandgap frequency range of the RCPM can be adjusted by altering the design. The elastic wave propagation in the metastructure was investigated by numerical and experimental approaches. The experimental results are in good agreement with the simulation, demonstrating bandgaps that occupy a much lower frequency range than what can be realized by Bragg scatter alone. The study provides a feasible approach to designing metamaterials for low-frequency vibration attenuation in engineering applications.