Conch shells are commonly found at beaches and are often used as pretty decorations in homes across the world. But researchers at the Massachusetts Institute of Technology (MIT) have found a new, perhaps more useful, use for the ordinary shell.
The humble conch shell is renowned for being tough, after all it has to cope with rocky shores, storms and protect its vulnerable interior from predators with exceptionally sharp teeth. As such, researchers have studied and used the conch shell to create a material that could potentially improve body armour and protective headgear forever.
Taking Inspiration from Nature
These exciting findings from MIT graduate Grace Gu, postdoc Mahdi Takaffoli and McAfee Professor of Engineering Markus Buehler have been published in the journal Advanced Materials. The reason that conch shells have been used for inspiration is due to the unique architecture they have that makes them up to 10 times tougher than a material called nacre, which is more commonly known as mother of pearl.
3D printing was used to try and replicate the structure of a conch shell by mimicking the criss-crossed layers. That is because the toughness of a conch comes from three layers that make it incredibly hard for any cracks to spread and potentially enlarge.
Grace Gu says, “the material has a zigzag matrix, so the crack has to go through a kind of maze” before it can spread any further. The complexity of a conch structure has meant that it couldn’t be replicated well until the recent development of 3D printing technology in the lab.
Evaluating The Toughness
Once the material was 3D printed, the next thing to do was to try to evaluate just how tough it is. The researchers carried out tests using a drop tower that specifically allowed them to observe the material to see how the cracks both appeared and spread after impact.
The results were found to be in agreement between both the experiments and the actual model, partly because they were able to 3D print the materials with precisely controlled structures. By making slight variations to the material in the future, they will be able to potentially optimise it even further.
The testing in particular found that materials that used the conch like geometry were found to be 85% better at preventing cracks than the strongest base material. They even proved to be 70% better than traditional fibre composite arrangement, Gu says. This means that there could be the potential for material using the conch-like structure in body armour and so forth.
An added benefit would be that due to this material being produced by 3D printing, there is also the potential to customise helmets or body armour as needed.