Octet lattice-based plate for elastic wave control

TL;DR

This paper explores the use of octet lattice-based plates with metastructures like metabarriers and metalenses to control elastic wave propagation, enabling wave mitigation, guiding, and focusing for vibration isolation and energy concentration.

Contribution

It introduces novel customized octet metastructures with tunable parameters for broad bandgap creation and wave filtering, including graded designs for rainbow trapping and wave steering.

Findings

Broad bandgap achieved in octet lattice array

Effective wave inhibition with metabarriers

Wavefront steering with metalenses

Abstract

Motivated by the importance of lattice structures in multiple fields, we investigate the propagation of flexural waves in a thin woven plate augmented with two classes of metastructures for wave mitigation and guiding, namely metabarriers and metalenses. The cellular architecture of this plate invokes the well-known octet topology, while the metadevices rely on novel customized octets either comprising spherical masses added to the midpoint of their struts or variable node thickness. We numerically determine the dispersion curves of a doubly-periodic array of octets, which produce a broad bandgap whose underlying physics is elucidated and leveraged as a design paradigm, allowing the construction of a metabarrier effective for inhibiting the transmission of waves. More sophisticated effects emerge upon parametric analyses of the added masses and node thickness, leading to graded designs that spatially filter waves through an enlarged bandgap via rainbow trapping. Additionally, Luneburg and Maxwell metalenses are realized using the spatial modulation of the tuning parameters and numerically tested. Wavefronts impinging on these structures are progressively curved within the inhomogeneous media and steered toward a focal point. Our results yield new perspectives for the use of octet-like lattices, paving the way for promising applications in vibration isolation and energy focusing.