bio

Bouligand structure

A layered arrangement in which each successive sheet of fibres sits rotated by a small constant angle from the one beneath, so the whole stack twists like a spiral staircase — commonly called twisted plywood. That erases every continuous plane through the material, so a crack has no straight path to follow: it is forced to corkscrew, generating new surface faster than it advances, which is the most expensive way to travel a crack can be given. Arthropod cuticle is built this way; the mantis shrimp's dactyl club survives impact accelerations above ten thousand gravities, thousands of times, without shattering.