Could a new wonder material allow you to reuse your cycling helmet after a crash?

Cycling helmets could have more efficient protection from shock in the event of a crash thanks to a new material that absorbs impact or vibration energy and is reusable, according to a recent study published in the Nature Materials journal. It's recommended that all current helmets should be replaced if involved in a crash, even if there doesn't appear to be any external damage.

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The new process discovered by researchers is said to create a material that can absorb more mechanical energy per gram with very good reusability, and this is claimed to be due to its unique nanoscale mechanism.

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Pressurised insertion of aqueous solutions into water-repellent nanoporous materials, such as zeolites and metal-organic frameworks, are said to help to create high-performance energy absorbing systems.

Researchers from the University of Birmingham and Oxford, along with Ghent University, experimented with hydrothermally stable zeolitic imidazolate frameworks (ZIFs) with a ‘hydrophobic’ cage-like molecular structure.

The findings of the study show that such systems are “remarkably effective energy absorbers at realistic, high-rate loading conditions, and this phenomenon is associated with the water clustering and mobility in nanocages”.

Co-author of the study and a Lecturer of Engineering at the University of Birmingham, Dr Yueting Sun, says that this material has potential for use in cycling products, thanks to its absorption qualities that deliver time and time again.

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Helmets are just one application the experts are looking into, who say that the material could be of "great significance" for vehicle crash safety, and also be uesed for military armour and shoe insoles. 

Yueting explains how this new material differs from what is used in current helmet systems and how this can be beneficial: “Conventional helmets are one time use, meaning that once a helmet has been subjected to a crash, it should be replaced. Even if the exterior looks undamaged, the inside energy absorption component, usually made of plastic foams such as expanded polystyrene (EPS), could have been crushed.

“As this material cannot spring back, the helmet will no longer offer a protection that it is designed for when subjected to another impact in future accidents. Having a new material that protects people from multiple impacts can be significant for helmet technology.

“Also, our material can be a fluid with a potential to manage rotational energy in oblique impacts which is an important cause of brain injury and concussion but remains a challenge for conventional helmets.

"Our material could offer a more effective helmet that can be safely reused."

Systems do already exist to combat rotational forces such as MIPS, which is a low friction layer that allows 10-15mm of relative motion between the helmet and head in all directions. More recently, Trek's accessories brand Bontrager introduced its technology called Wavecel, which it says is "proven to be up to 48 times more effective than standard EPS foam at preventing concussions", and is designed to deal with angled impacts.  

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Not only can this new material benefit helmet development in cycling; Yueting notes that it can also be used as shock absorbers for bike suspension. “The reusability of the material, stemming from the spontaneous liquid extrusion, also enables the material to be suitable for damping purposes.

“It essentially combines the functions of a damper and spring, making it possible to design a lighter and smart suspension.”

The full research paper, called 'High rate nanofluidic energy absorption in porous zeolitic frameworks', can be found here.