• Fiber-composite inertial amplification metamaterials are proposed. • Proposed metamaterials were manufactured by assembling 3D-printed composite parts. • Partial embedding of continuous carbon fibers widens the band gap. • Band-gap width and attenuation were maximized using band-structure analysis. This paper proposes octahedral inertial amplification metamaterials reinforced with continuous carbon fibers as lightweight structures for broadband attenuation of multidirectional vibrations. The band structures of the metamaterials were obtained using the finite element method and show that the partial embedding of continuous carbon fibers causes a significant band-gap expansion. The band-gap boundary mode shapes were analyzed to elucidate the underlying mechanisms by which continuous fiber reinforcement widens the band gap. The dimensional parameters of the metamaterials were then optimized to maximize the band-gap width. The maximum achievable band-gap width of the proposed metamaterial was substantially larger than that of the unreinforced structure. In addition, an optimization to further enhance the attenuation, extracted from the complex band structure, was conducted as an optional design procedure following the band-gap width maximization. This procedure improves the attenuation within a target frequency range inside the band gap, albeit at the expense of the band-gap width. The optimized metamaterials were prepared by assembling components fabricated using a fiber-composite 3D printer. Hammering tests were performed to measure accelerance for multidirectional excitations. The measured accelerance exhibited a pronounced reduction within the numerically predicted band gap. These experimental results validate the effectiveness of the optimization designs.
Mizukami et al. (Fri,) studied this question.