3D-prints reveal how strong seashells are
doi:10.1038/nindia.2015.77 Published online 5 June 2015
Nature has engineered ceramic shells of molluscs like clams, oysters, and snails to withstand high pressures at the ocean bottoms, shows a recent study1. The findings could help engineers build stronger materials for use in transport or defence.
© Tiwary, C. S. et al
For this study, the team from from the Indian Institute of Science, Bangalore, in collaboration with the Ajayan Pulickel lab at Rice University, Texas, USA, modelled and printed two types of shells using a 3D-printer. They looked at a fan-shaped shell, like that of clams; and a cork-screw-like shell of auger snails. By subjecting both the natural and printed shells to high pressure tests, and observing their cracks, the team inferred that it is Nature’s selection of shell shapes, rather than just their chemical composition that holds the clue for the sturdiness.
© Tiwary, C. S. et al.
While the animal hides within the narrow region of a screw-like shell, it relieves the load as cracks at the wider top area of the shell, thus protecting the animal inside. The interesting finding is that they found the same crack patterns in both the natural and printed shells under pressure test, explains Tiwary. “[Our study] shows how such shapes play an important role in load transfer in the structure."
The team is now studying other shapes of mollusc shells. Tiwary is optimistic about the use of such shells in building protective structures and similar applications.
Marc Meyers at the University of California, San Diego, says the study has looked only into macrostructures to explain the hypothesis. Future studies should go into the finer micro- or nano-structure levels. Vincent Sherman, Meyer's graduate student, thinks the study’s strength lies in the choice of the methodology to show the stress-handling regions of the shells.
References
1. Tiwary, C. S. et al. Morphogenesis and mechanostabilization of complex natural and 3D printed shapes. Sci. Adv. 1, e1400052 (2015) doi: 10.1126/sciadv.1400052
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