The shells of marine organisms are known for their toughness.
They can take a beating from storms and tides,
as well as rocky shores and sharptooth predators.
But one shell, in particular, stands out
above all others in its toughness.
That shell is the conch.
And now, researchers at MIT have been
able to show that the conch shell's superior strength could
be reproduced in engineered materials.
The secret to the conch's extraordinary resilience
is in the shell's geometry.
The conch has a three-tiered structure,
composed of multiple layers, in which
the grain of the molecular structure
goes in different directions, creating a sort of maze
that a crack would have to travel through,
in order to spread.
In their lab at MIT, the researchers
developed the 3D printing technology
that allows them to duplicate the exact structure
of the conch shell.
Their composite consists of polymer materials
with different degrees of strength and resilience,
printed in a three-tiered, zigzag matrix.
Part of the innovation of this project
was the team's ability to both simulate the material's
behavior, and analyze its actual performance
under realistic conditions.
So for this work, the researchers
simulated tests on the computer, and then did actual tests
in a drop tower, allowing them to observe exactly how cracks
appeared and spread in the first instance of impact.
What they saw was, the 3D printed sample
with a simple geometry, cracks immediately and dramatically,
whereas their 3D printed sample that
mimics the geometry of a conch, took on the force
with barely any cracking on impact.
Now that the researchers have cracked the conch-shell code,
they can start to focus on making slight tweaks
and variations for future optimization.
And because of the use of 3D printed technology,
the researchers say this system could
make it possible to produce individualized helmets,
or other body armor--
tailored and personalized for a specific person--
with optimal protection and performance.