Shear Wave Filtering in Naturally-Occurring Bouligand Structures

TL;DR

This study investigates wave propagation in Bouligand structures of crustacean dactyl clubs, revealing bandgap-induced wave filtering that enhances impact resistance beyond known macroscopic properties.

Contribution

It introduces a combined layered and periodic modeling approach to demonstrate wave filtering via bandgaps in natural Bouligand structures.

Findings

Identification of bandgaps at impact-related frequencies

Wave filtering mechanism in natural materials

Enhanced impact resistance due to wave filtering

Abstract

Wave propagation was investigated in the Bouligand-like structure from within the dactyl club of the Stomatopod, a crustacean that is known to smash their heavily shelled preys with high accelerations. We incorporate the layered nature in a unitary material cell through the propagator matrix formalism while the periodic nature of the material is considered via Bloch boundary conditions as applied in the theory of solid state physics. Our results show that these materials exhibit bandgaps at frequencies related to the stress pulse generated by the impact of the dactyl club to its prey, and therefore exhibiting wave filtering in addition to the already known mechanisms of macroscopic isotropic behavior and toughness.