Researchers from the University of Gothenburg and the University of Siena have developed an innovative shock-absorbing material structure for bicycle helmets, based on advanced geometric design. Using auxetic metamaterials, the material offers improved protection in the event of impact — an innovation that could inspire new applications in product design, mobility, and safety equipment.

Smart geometry for better energy absorption
Traditional bicycle helmets typically rely on foam layers to absorb impact energy. This new research takes a different approach by designing a material with a carefully calculated geometric pattern that distributes impact forces more effectively. The structure is based on auxetic metamaterials, which expand laterally when stretched, unlike conventional materials. This unusual behaviour increases the material’s ability to absorb and dissipate impact energy. In practice, it reduces the risk of head injuries by minimising the force transferred to the wearer.

The researchers used design optimisation methods to develop the best possible geometric configuration, resulting in a hyperelastic polymer lattice that deforms predictably under different types of impact.

3D printed and customisable
The innovative structure was manufactured using advanced 3D printing technology, making it possible to produce the complex geometry with high precision. One of the key advantages of this approach is the potential for customisation: helmets could be printed to fit an individual’s exact head shape, offering a better fit and increased comfort.

While the current prototype is slightly larger and heavier than standard bicycle helmets, the design delivers superior protection. The researchers also highlight the potential of this technology for broader applications beyond cycling, including in the automotive sector, sportswear, and personal protective equipment.

Broad potential and sustainable benefits
This material innovation is particularly relevant for product designers, mobility designers, and automotive specialists interested in improving safety without compromising comfort or aesthetics.

Moreover, the use of additive manufacturing opens up opportunities for more sustainable production. 3D printing reduces material waste by producing only what is needed and enables local, on-demand manufacturing. In the future, the material could potentially be combined with bio-based or recyclable polymers, further enhancing its circularity and environmental performance.

Ultimately, this research demonstrates how innovative geometric design and advanced materials can reshape the way we think about safety equipment — with possible applications ranging from helmets to automotive interiors and sports protection gear.

Source: University of Gothenburg via EurekAlert!
Image: Mohammad Hossein Zamani