Researchers at the University of California, Riverside and Purdue University are closer than ever to building a strong composite material thanks to inspiration from the mantis shrimp. The mantis shrimp is a small, colorful marine crustacean that has the brutal strength to smash its prey’s shells using its dactyl club, which is similar to a human fist.
This latest study was published in Advanced Materials journal and discusses a newly found herringbone structure that has never been documented in nature that is contained within the outer layer of the dactyl club appendage. The structure shields the club upon impact and allows the mantis shrimp to cause an astounding amount of damage.
Mantis shrimp come in two forms, ‘smashers’ and ‘spearers’. Smashers kill prey with hard shells, such as snails and crabs, by shattering them with amazing force and speed. The dactyl club is able to reach speeds of 10,000g, showering brutal impacts that have the same speed as a .22 caliber bullet.
For eight years, David Kisailus and his team have been studying the dactyl clubs of smashers and using them in order to help create a new generation of composite materials. Researchers have identified many different regions throughout the club. The interior region is named the periodic region and is made up of an energy-absorbing structure that helps to filter our shear waves, which are present within objects that are put under high stress. The region is made of two phases: an organic phase and an inorganic phase. Current research surrounds the club’s outermost layer, known as the impact region.
This particular region is special because it has a layer that is completely resistant to cracks. It contains crystalline calcium phosphate (which is a mineral found in human bone) that encompasses the organic chitin fibers. Upon closer inspection, researchers discovered that the mineralized fibers were highly compacted in order to form a “herringbone structure” that is far tougher than structures within the periodic region. The herringbone structure both protects the club from incoming damage and force while also enabling the shrimp to cause astounding amounts of damage by simply transferring increased momentum during impact.
Nicholas Yaraghi, a student in Kisailus’ group who led the research said this is the first time the herringbone structure has been seen in nature. Yaraghi said until their observations it was not known that the properties within this high impact-resistant material were created by the herringbone structure. Kisailus and his research group tested this hypothesis by taking a deeper look at the role of each structure and fabricating the herringbone structure using synthetic material along with a 3D printer.
Models were built by Pablo Zavattieri, Associate Professor of Civil Engineering and University Faculty Scholar at Purdue University along with his team in order to replicate the herringbone structure. The models explained that stress is able to be distributed evenly, preventing structural damage. Compression testing of the 3D printing biomimetic composite was used in order to prove that the herringbone causes the entire region to be more effective in comparison to the periodic region when it comes to deflecting cracks and managing stress.
This type of unique strength holds the potential to be used in a wide range of applications, including aerospace, automotive and armor. Kisailus says the more that is uncovered about the mantis shrimp and its multi-layer design, the more researchers continue to learn about better design techniques for planes, cars, sports, equipment and even armor. With recent advancements in 3D printing, modeling is becoming easier. This means translating the mantis shrimp’s weapon into new materials will quickly turn into an obtainable reality.