Although sea shells of various types have been studied as sources of inspiration for impact-resistant manmade materials, the conch shell is known for being particularly tough. And while the reason for its toughness was already understood, it hadn't been replicated using engineered materials – until now, that is.
The conch shell is made up of three layers, with the grain running in a different direction in each one. This means that when it's subjected to an impact, cracks can't just run straight through it. Instead, they have to follow a sort of zig-zagging path, which dissipates much of their energy.
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Using a 3D printer, a team at MIT has reproduced that structure out of composite materials. When subjected to drop tests (in which a weight is dropped on samples), the conch-inspired material was 85 percent better at preventing crack propagation than samples of the base material without the conch-like structure. It was also 70 percent better than a traditional fiber composite.
Testing proved that the geometry with the conch-like, criss-crossed features (right) was substantially better at preventing crack propagation (Credit: Melanie Gonick/MIT)
It is now hoped that by subtly tweaking the structure of the material, it could be optimized for applications such as lightweight body armor.
The study was conducted by MIT graduate student Grace Gu, postdoc Mahdi Takaffoli, and McAfee Professor of Engineering Markus Buehler. There's more information in the video below.