New findings from researchers at Purdue University and the University of California Riverside, revealing the structure of a mantis shrimp’s impact-resistant claw, also known as a “dactyl club,” are inspiring the development of advanced materials for potential applications in body armor, helmets and components for buildings and cars. The club is made of a composite material containing fibers arranged in a “helicoidal structure” that resembles a spiral staircase.
The findings build on previous research, reported last year, which proved the club’s helicoidal structure is naturally designed to survive repeated high-velocity impact. The universities’ new findings reveal that the fibers are also arranged in a “herringbone pattern” in the shrimp shell’s outer layer. According to the team, this is the first time the unique herringbone structure has been observed in nature.
The researchers were able to fabricate a herringbone structure using synthetic materials and a 3-D printer. Pablo Zavattieri, an associate professor in Purdue’s Lyles School of Civil Engineering, and Purdue doctoral student Nicolas Guarín-Zapata built computational models that replicate the herringbone structure. The work was performed in collaboration with David Kisailus, the Winston Chung Endowed Professor in Energy Innovation at UC Riverside, and UC Riverside graduate student Nicholas A. Yaraghi.
“By using 3-D printing techniques like those used by Zavattieri’s team, we can actually take what we’ve learned about the architecture of the dactyl club and manufacture new composites with traditional engineering materials like polymers and carbon fiber,” Kisailus said.
Compression testing of the 3-D printed 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.
“Near the surface, instead of having fibers, you have a transition to nanoparticles, and we think these nanoparticles serve the function of distributing the stress,” Zavattieri said.
The potential application of these new composites would be another example of how digital fabrication technologies can interact with the biological world. During the recent American Institute of Architects show in Philadelphia, MIT professor Neri Oxman inspired an audience of architects with her vision of “material ecology,” which spans the intersection of additive manufacturing, materials engineering, synthetic design, and computational design. Her TED Talk on the subject has over a million views and is spurring conversation around the world.
Purdue and UCR are already working on fabricating second-generation composites that incorporate features inspired by the mantis. For more information, read A Sinusoidally Architected Helicoidal Biocomposite.