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Marine sponges inspire next-generation architecture

Researchers in the US are investigating the properties of marine sponges - bioinspired architecture that could pave the way for stronger, lighter structures of buildings and bridges.

In a new study, researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A Paulson School of Engineering and Applied Sciences (SEAS) showed that the diagonally-reinforced square lattice-like skeletal structure of the deep-water marine sponge, Euplectella aspergillum, has a higher strength-to-weight ratio than the traditional lattice designs that have been used for centuries in the construction industry. 

“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,” said Matheus Fernandes, a graduate student at the Wyss Institute and SEAS. 

SEAS senior scientist James Weaver explained that in many fields, such as aerospace engineering, the strength-to-weight ratio of a structure is critically important, adding that the biologically-inspired geometry could provide a roadmap for designing lighter, stronger structures for a wide range of applications.

Many applications people encounter in everyday life, such as walking through a covered bridge or putting together a metal storage shelf, often feature diagonal lattice architectures. This type of design uses many small, closely spaced diagonal beams to evenly distribute applied loads.

“Town developed a simple, cost-effective way to stabilise square lattice structures, which is used to this very day,” said Fernandes. “It gets the job done, but it’s not optimal, leading to wasted or redundant material and a cap on how tall we can build.”

Fernandes added: “One of the main questions driving this research was can we make these structures more efficient from a material allocation perspective, ultimately using less material to achieve the same strength?”

To achieve this, the deep-sea glass sponges, the group to which Euplectella aspergillum – otherwise known as Venus’ Flower Basket – belongs had a nearly half billion-year head start on such research and development. 

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

“We’ve been studying structure-function relationships in sponge skeletal systems for more than 20 years, and these species continue to surprise us,” said Weaver.

In simulations and experiments, the researchers replicated this design and compared the sponge’s skeletal architecture to existing lattice geometries. As a result, they found that the sponge design outperformed them all, withstanding heavier loads without buckling. 

The researchers also found that the paired parallel crossed-diagonal structure improved overall structural strength by more than 20 per cent, without the need to add additional material to achieve this effect.

“Our research demonstrates that lessons learned from the study of sponge skeletal systems can be exploited to build structures that are geometrically optimised to delay buckling, with huge implications for improved material use in modern infrastructural applications,” said Katia Bertoldi, a professor of Applied Mechanics at SEAS. 

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