Sea sponge

Taking building tips from a glass sponge

This humble deep-sea glass sponge may inspire a new generation of construction.

Credit: Matheus Fernandes/Harvard SEAS

It has long been known that the Venus Flower Basket (Euplectella aspergillum) is tough, but now engineers at Harvard University, US, have shown that its skeletal structure has a higher strength-to-weight ratio than the traditional lattice designs used for centuries in buildings and bridges.

“We found that the sponge’s diagonal reinforcement strategy achieves the highest buckling resistance for a given amount of material, which means that we can build stronger and more resilient structures by intelligently rearranging existing material within the structure,” says Matheus Fernandes, first author of the paper in the journal Nature Materials.

To support its tubular body, E. aspergillum employs two sets of parallel diagonal skeletal struts that intersect over and are fused to an underlying square grid, to form a robust checkerboard-like pattern.

In simulations and experiments, Fernandes and colleagues replicated this design and compared the sponge’s skeletal architecture to existing lattice geometries. The sponge design outperformed them all, they say, withstanding heavier loads without buckling.

The research showed that the paired parallel crossed-diagonal structure improved overall structural strength by more than 20%, without the need to add additional material to achieve this effect.

“In many fields, such as aerospace engineering, the strength-to-weight ratio of a structure is critically important,” says James Weaver, a corresponding author. “This biologically-inspired geometry could provide a roadmap for designing lighter, stronger structures for a wide range of applications.”

The researchers believe their approach can be extended to design structures over a wide range of length scales, but do note in their paper that their analysis “did not account for the effect of gravity, which could become an important source of loading for large-scale structures”.

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