Conch shells inspire 3D-printed body armour
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The internal structure of conch shells has inspired a new composite material, which could form the basis for strong, specialised helmets and other body armour.
Marine molluscs such as abalone, whelks and winkles need to be tough to withstand the beating of storms and hungry predators. Perhaps the toughest of the lot is the conch. Conches – which have thick, attractive shells with high spires and points at both ends – are remarkably resistant to fracture.
“[Conch shells] have this really unique architecture,” said Grace Gu, a graduate student at Massachusetts Institute of Technology (MIT) and an author of the study.
The toughness of conch shells arises from their unique internal structure. The shells have three-tier structures which render them impact-resistant; according to Gu, cracks have to pass through a “kind of maze” of a “zigzag matrix” in order to spread through the shell.
By reproducing this inbuilt strength in artificial materials, the MIT researchers hope to develop the most effective protective helmets and armour ever made.
The team simulated the conch shell with various materials with different levels of “hierarchy”. The materials were then dropped in a tower, and the researchers observed how cracks appeared and spread after crashing to the ground. They found that the higher-level materials – those with a greater number of tiers – were much more resistant to cracking than the lower-level materials.
The conch-like material that they developed was 70 per cent more effective than a conventional fibre composite arrangement at preventing cracks from propagating.
This is a composite material, comprising various materials layered on top of each other with a 3D printer and their grains at different orientations. The combination of materials gives the composite strength (resistance to damage) and toughness (ability to dissipate energy) through the entire material.
According to Professor Markus Buehler, head of the department of Civil and Environmental Engineering at MIT, the new material has the stiffness of glass and ceramics, but without the drawback of their brittleness.
As the material is compatible with 3D printers, it could form the basis of highly specialised helmets and other body armour, the team report in Advanced Materials.
“[Each helmet could be] tailored and personalised; the computer would optimise it for you, based on a scan of your skull, and the helmet would be printed just for you,” said Gu.