Design and three-dimensional printing of carbon-fiber-composite elastic metamaterials with inertial amplification mechanisms

Elastic metamaterials with inertial amplification mechanisms reinforced by continuous carbon fibers were proposed to achieve lightweight structures with a wide band gap in the low frequency range (< 1 kHz). Finite-element method analysis was performed to investigate the effect of continuous fibers on the specific stiffness and band gap width. The specific stiffness and band gap width can be improved by an appropriate placement of continuous carbon fibers. The dimensions of the proposed structure were optimized to maximize the band gap width. A gap-mid-gap ratio greater than 100% was achieved by optimization. Analytical modeling was performed to predict the lower and upper bound frequencies of the band gap, and its accuracy was verified by a comparison with the finite-element analysis. The optimized structure was fabricated by a threedimensional printer that can print composites with curvilinear continuous fibers. The frequencydependent vibration transmissibility of the printed metamaterial structure was measured and compared with frequency response functions obtained from finite-element analysis. The measured attenuation performance of the manufactured structure agreed well with the numerical analysis results.