Like a little crustacean warrior, the long-lived mantis shrimp can go about its daily activities hunting for prey using their small but powerful arms. These creatures evolved a special type of weapon that can withstand a surprising amount of force.

Research conducted by engineers at the University of California, Riverside and Purdue University gave these experts an idea of how to come up with armors and helmets tough enough to withstand strong forces.

"The mantis shrimp is able to repeatedly pummel the shells of prey using a hammer-like appendage that can withstand rapid-fire blows by neutralizing certain frequencies of "shear waves," the researchers say.

Chitin, the same substance found in many other crustacean shells and exoskeletons, comprises the composite material that makes up the club.  It has a helicoidal structure similar to that of a spiral staircase which is designed to hold strong against high-velocity blows.  It filters out certain frequencies of waves which can be damaging.

Engineers are conducting an ongoing study to develop new types of composite materials that could serve the same purpose.  The same filtering principles, for example, could be used for aerospace and automotive frames and even body armor and helmets.

The researchers patterned the structure to the same mathematical equations used to study materials in solid-state physics and photonics, showing the structure possesses "bandgaps" that filter out the damaging effects of shear waves travelling at the speed of sound.  Findings were recorded in an online journal in May and will appear in print in Acta Biomaterialia.  Nicolás Guarín-Zapata, a doctoral student at Purdue, is the paper's head author.  Guarín-Zapata wrote the findings with co-authors Juan Gomez who is a researcher from the Civil Engineering Department, Universidad EAFIT, Medellín, Colombia and doctoral student Nick  Yaraghi from UC Riverside, David Kisailus - Professor in Energy Innovation at UC Riverside and Pablo Zavattieri who is a University Faculty Scholar at Purdue and an associate professor in the Lyles School of Civil Engineering.

Zavattien calls it amazing, how the smasher mantis shrimp hits many times a day.  The 'dactyl club' can reach an acceleration of 10,00 Gs - one causing impacts in the same way a 22-caliber bullet can.

An ongoing concept, the research will include efforts to create synthetic materials with filtering properties.  "This is a novel concept.  It implies that we can make composite materials able to filter certain stress waves that would otherwise damage the material," adds Kisailus.

The research is funded by the National Science Foundation and the US Air Force Office of Scientific Research.

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