Mantis shrimp inspires next-gen, ultra-strong materials

The fist-like appendage of mantis shrimp - a small, multicoloured marine organism - consists of a unique herringbone structure, that may be used to design super strong composite materials for variety of applications, including aerospace and armour, scientists say.
The mantis shrimp crushes the shells of its prey using a fist-like appendage called a dactyl club.
Researchers at the University of California, Riverside and Purdue University in the US describe for the first time the unique herringbone structure, not previously reported in nature, within the appendage's outer layer.
It is this tough herringbone structure that not only protects the club during impact, but also enables the mantis shrimp to inflict incredible damage to its prey.

The dactyl club can reach an acceleration of 10,000g, unleashing a barrage of impacts with the speed of a .22 caliber bullet.
In previous work, researchers identified several different regions of the dactyl club, including an interior region - called the periodic region - with an energy-absorbent structure that also filters out damaging shear waves, which travel through objects when they are under stress.

The current research describes for the first time a unique herringbone structure within the dactyl club's outer layer, called the impact region.
The impact region is a crack-resistant layer that shields the club as the mantis shrimp pummels its prey. It consists of crystalline calcium phosphate (the same mineral found in human bone) surrounding the organic chitin fibres.

Researchers found that these heavily mineralised fibres were compacted to form a "herringbone structure" that is significantly stiffer than the periodic region.
This unique herringbone structure not only protects the club from failure, but also enables the mantis shrimp to inflict incredible damage to its prey by transferring more momentum upon impact.
Researchers performed finite element analyses to understand the role of these structures. They also fabricated the herringbone structure using synthetic materials and a 3D printer.
They built computational models that replicate the local details of the herringbone structure.
These models explained that damaging stress can be more uniformly distributed, mitigating catastrophic structural failure.

Compression testing of the 3D printing biomimetic composite also helped prove that the herringbone structure makes the impact region even more effective than the periodic region in redistributing stress and deflecting cracks.
The discovery of the highly impact-resistant herringbone structure adds new inspiration as his team designs the next generation of materials for a variety of applications, including aerospace, automotive and armour, researchers said.
The study was published in the journal Advanced Materials.