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Sea sponges inspire the next generation of skyscrapers and bridges



Sea sponges inspire the next generation of skyscrapers and bridges

The skeleton of Euplectella aspergillum, a sea sponge in deep water. Photo credit: Matheus Fernandes / Harvard SEAS

When we think of sponges, we tend to think of something soft and squishy. Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) are using the glassy skeletons of sea sponges as inspiration for the next generation of stronger and taller buildings, longer bridges and lighter spacecraft.

In a new article published in Natural materialsThe researchers showed that the diagonally reinforced square lattice-like skeletal structure of Euplectella aspergillum, a sea sponge found in deep water, has a higher strength-to-weight ratio than the traditional lattice structures that have been used for centuries in the construction of buildings and bridges.

“We found that the sponge̵

7;s diagonal reinforcement strategy gives the highest buckling resistance for a given amount of material. This means that we can build stronger, more resilient structures by intelligently rearranging existing material within the structure,” said Matheus Fernandes, PhD student at SEAS and first author of the paper.

“In many areas such as aerospace, the strength-to-weight ratio of a structure is critical,” said James Weaver, Senior Scientist at SEAS and a co-author on the paper. “This biologically inspired geometry could provide a roadmap for designing lighter, stronger structures for a variety of applications.”







The skeleton of Euplectella aspergillum, a sea sponge in deep water. Photo credit: Video courtesy of the Learning Lab at Harvard Bok Center

If you’ve ever walked through a covered bridge or put together a metal shelf, you’ve seen diagonal lattice architecture. This type of construction uses many small, tightly spaced diagonal beams to evenly distribute the applied loads. This geometry was patented in the early 19th century by the architect and civil engineer Ithiel Town, who wanted a method of making strong bridges from lightweight and cheap materials.

“Town developed a simple and inexpensive way to stabilize square lattice structures that is still used today,” said Fernandes. “It does the job but is not optimal, resulting in wasted or redundant material and limiting the amount of our construction costs. One of the main questions in this research has been whether we can make these structures more efficient from a material allocation perspective, ultimately using less material, to achieve the same strength? “

Fortunately, the glass sponges that included Euplectella aspergillum – also known as Venus’ flower basket – had a head start on research and development by nearly half a billion years. To support its tubular body, Euplectella aspergillum uses two sets of parallel diagonal skeletal struts that intersect and fuse with an underlying square grid to create a sturdy checkerboard-like pattern.

Sea sponges inspire the next generation of skyscrapers and bridges

Composite rendering that transitions from a glassy sponge skeleton on the left to a rebar-based welded mesh on the right, highlighting the biologically inspired nature of the research. Photo credit: Courtesy Peter Allen, Ryan Allen, and James C. Weaver / Harvard SEAS

“We have 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 skeletal architecture of the sponge with existing lattice geometries. The sponge design surpassed them all and withstood heavier loads without kinking. The researchers showed that the paired parallel cross-diagonal structure improved overall structural strength by more than 20 percent without the need to add additional material to achieve this effect.

“Our research shows that lessons learned from studying sponge skeletal systems can be used to build structures that are geometrically optimized to retard buckling, which has a huge impact on improved material utilization in modern infrastructure applications,” said Katia Bertoldi, William and Ami Kuan Danoff Professor of Applied Mechanics at SEAS and corresponding author of the study.


Study results show that not all of nature’s layered structures are as hard as animal shells and antlers


More information:
Matheus C. Fernandes et al., Mechanically robust grids, inspired by deep-sea glass sponges, Natural materials (2020). DOI: 10.1038 / s41563-020-0798-1

Provided by the Harvard John A. Paulson School of Engineering and Applied Sciences



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