Beautiful natural pattern could hold secret to next-gen body armour

8 Aug 2018

Police officer wearing body armour. Image: John Gomez/Shutterstock

Researchers believe the natural patterns found on seeds could hold the secret to creating highly advanced body armour and other smart materials.

There are some truly spectacular patterns found in nature. Among them is that found on the seed coating of plants known as verdolaga or purslane.

Using a microscope, the building blocks of the seed coating can be seen as star-shaped cells which move by zig-zag intercellular joints forming a tiled exterior. This protects the seed inside from mechanical damage and other environmental stresses such as drought or freezing.

Now, in a paper published to Advanced Materials, a team of researchers from the University of New Hampshire believes this pattern could hold the secret to a whole range of smart materials for items such as body armour, screens and aircraft panels.

With nature providing the blueprint, the team set about building prototypes to better understand the relationship between the seed coating’s structural attributes.

These prototypes were built using a multi-material 3D printer, and mechanical experiments and simulations performed on them.

Seed pattern magnified

From top right: (A) The verdolaga flower. (B) Tiny black seeds from a verdolaga. (C) Image of the verdolaga seed coating. (D) Magnified area of the seed coating. Images: University of New Hampshire

More waves, please

The experiments showed that the waviness of the seed coating’s mosaic structure – called sutural tessellations – play a key role in its protective powers.

This means that with more waves built into the surface, the more applied loads can be shifted from the softer parts to the harder parts of the material.

Essentially, the wavier it is, the stronger it is.

“Imagine a window, or the exterior of an [aircraft], that is really strong but not brittle,” said Yaning Li of the research team.

“That same concept could create smart material that could be adapted to behave differently in different situations whether it’s a more flexible body armour that is still protective or another such materials.”

The researchers also said that the design principles showed serious promise for increasing the mechanical performance of tiled composites in materials built by humans.

And, as its strength can be simply tuned by increasing its waviness, it could soon be easily producible by large manufacturers.

Police officer wearing body armour. Image: John Gomez/Shutterstock

Colm Gorey was a senior journalist with Silicon Republic