Torsional bandgap switching in metamaterials with compression-torsion interacted origami resonators

Torsional vibrations are unavoidable in beam-type structures in various engineering practices, and the advent of metamaterials provides a solution through the generation of bandgaps. However, unlike their flexural counterparts, tunable torsional bandgaps are seldomly studied due to two major difficulties: the existing metamaterial's units are less torsional-sensitive and the reliable torsional sensing techniques for validations are less available. In this work, switchable torsional bandgaps are realized in a metamaterial beam with a bistable resonator design based on Kresling origami with attached eccentric balls. We find that, through compression-torsion interaction of the proposed origami resonators and the corresponding wave-coupling phenomenon, torsional bandgaps can be generated and efficiently tuned, which leads to lower and wider vibration isolation frequency zones. Thanks to bistability, Kresling resonators arranged with eccentric balls can achieve bandgap switching. Specifically, based on the compression-torsion interaction of the bistable Kresling origami, wave coupling will be weakened/enhanced when the Kresling resonators arranged with eccentric balls turn from the 1st/2nd state to the 2nd/1st state, and, thus, the switching of torsional bandgaps can be realized. In order to experimentally validate the tunable torsional bandgaps, a high-sensitive fiber Bragg grating (FBG) displacement sensing system containing two parallel FBG sensors is set up to extract the torsional responses. This research will be helpful for future studies focusing on regulating torsional waves through compression-torsion interaction and mode conversion utilizing wave coupling. Published under an exclusive license by AIP Publishing.

Automated summary

This study demonstrates the realization of switchable torsional bandgaps in a metamaterial beam with a bistable resonator design based on Kresling origami with attached eccentric balls. By leveraging compression-torsion interaction and wave-coupling phenomenon, it is shown that torsional bandgaps can be generated and efficiently tuned, leading to lower and wider vibration isolation frequency zones. Additionally, bistability allows for bandgap switching in the Kresling resonators arranged with eccentric balls, providing potential applications in regulating torsional waves and mode conversion through wave coupling.