Tunable band structures design for elastic wave transmission in tension metamaterial chain

This paper reports a novel band structure manipulation mechanism stemmed from taut strings to shift the Bragg and local resonance band gaps simultaneously. We first developed a metamaterial chain encompassing periodic tighten strings, which are essentially elastic foundations with tunable effective stiffnesses controlled by the tensions of the grounded strings. Subsequently, band edge functions were analyzed against the tension applied, thereby revealing an ultra-wide band gap with a tunable pass band. Nonlinear dispersion characteristics of the proposed system were further corrected by multiple-scale perturbation, and the band gap boundaries are reduced slightly with larger incoming amplitudes. Transmission spectra of the finite specimen indicated reasonable agreement with theoretical analysis. With respect to the band-pass property, a very narrow band filter was achieved with a precise frequency selection. It was shown that, by actively tuning string tensions, broader attenuation bands appear; tightening strings in different locations could be used to control different frequency branches. The space-time distribution of the transmitted wave also confirmed that the pass band would narrow to the specified band by the tension design. This work enables broadband wave blocking and meticulous wave filtering through proper string tensions.