Natures wonders: glass sponge lattice design (Introduction)

by David Turell @, Tuesday, January 12, 2021, 21:41 (11 days ago) @ David Turell

Better than past human engineered design:

https://www.quantamagazine.org/the-curious-strength-of-a-sea-sponges-glass-skeleton-202...

"The skeleton is indeed made of glass, which the animal, Euplectella aspergillum — nicknamed “Venus’ flower basket,” — creates using acid extracted from seawater.

"Scientists still marvel at this sponge 180 years later. Its notable properties include stunning longevity — some glass sponges are thought to live many thousands of years, placing them among the longest-lived animals — and the ability to channel light through its silica strands in the manner of fiber optics. For the last two decades, a group of biologists, materials scientists and engineers at Harvard University has focused on the feature of Venus’ flower basket that attracted Owen: the intricate design of its glass skeleton. Their recent work reveals that the skeleton is, for unknown reasons, exceptionally strong — nearly as uncrushable as possible for this kind of structure.

“'It’s sort of the holy grail of engineering design,” said Dhruv Bhate, an associate professor of engineering at Arizona State University who studies the Venus’ flower basket but is not involved in the work of the Harvard team.

"The skeleton’s strength derives from its peculiar lattice pattern, which first intrigued the Harvard materials scientist and chemist Joanna Aizenberg about 20 years ago. Katia Bertoldi, one of Aizenberg’s co-authors on the recent studies, was also captivated by the lattice pattern as soon as she saw it. “It’s this periodic architecture, but it’s not a simple one,” Bertoldi said. She and her colleagues wondered, “Why this particular architecture?”

***

"For well over a century, engineers’ preferred design for trusses has been a sturdy lattice consisting of a square grid with diagonals running in both directions for added support. “We’ve been doing this the same way for a long, long time,” said Matheus Fernandes, a graduate student on the team. The skeleton of the Venus’ flower basket, however, has pairs of diagonals running in both directions rather than the single diagonals crisscrossing a typical truss. These pairs are spaced apart so the grid looks like a checkerboard, with diagonals crossing every other square.

***

"In simulations and experiments, they saw the bio-inspired lattice withstand the most stress — first from compression in one direction, and then from opposing pressures at three points in another test — before breaking. In further simulations, they varied the number of diagonals as well as their spacing and thickness to find the lattice that could sustain the most compression. It turned out to be the one modeled on the sponge.

"With its additional diagonals, the sponge’s lattice has more joints than a traditional truss and less distance between the joints, which may allow the structure to sustain greater compression before buckling, Fernandes said.

Comment: A designing mind is what must have made this structural plan, better than any thought of by human engineers


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