Researchers from the Harvard School of Engineering and Applied Sciences John A. Paulson (SEAS) uses the glass skeletons of sea sponges as inspiration for the next generation of stronger and taller buildings, longer bridges, and lighter spaceships. In a new paper published in Nature Materials, the researchers showed that the diagonally reinforced square lattice skeletal structure of Euplectella aspergillum, a deep-sea sponge, has a higher strength-to-mass ratio than the traditional lattice structures that have been used for centuries in the construction of buildings and bridges.
In their study, the researchers found that the sponge’s diagonal reinforcement strategy provides the highest buckling resistance for a given amount of material — its body. “We can create stronger and more resilient structures by intelligently rearranging existing material in the structure,” explains Mateus Fernandez, a graduate student at SEAS and first author of the paper.
“In many areas, such as aerospace engineering, the strength-to-weight ratio of a structure is critical,” adds James Weaver, SEAS Senior Scientist, and co-author. “This biology-inspired geometry can provide a roadmap for the development of lighter, stronger structures for a wide range of applications.”
If you’ve ever walked across a covered bridge or assembled a metal storage shelf, you’ve seen diagonal grid architecture. This type of design uses many small, closely spaced diagonal beams to evenly distribute the applied loads. This geometry was patented in the early 1800s by the architect and civil engineer Ithiel Town, who wanted to create strong bridges from lightweight and cheap materials.
Town developed a simple and economical way to stabilize square lattice structures that is still in use today. It does its job, but it is not optimal, which leads to waste or waste of material and limiting the height of the building. “One of the main questions on which this study was based was whether we can make these structures more efficient in terms of material distribution. ending up using less material to achieve the same strength? ” – explains Fernandez.
Glass Sponges, the group to which Euplectella aspergillum, also known as the Venus Flower Basket, belongs, had a head start of nearly half a billion years in research and development. To support its tubular body, Euplectella aspergillum uses two sets of parallel diagonal skeletal struts that intersect and merge with the underlying square mesh to form a durable checkerboard pattern.
“We’ve been studying the relationships between structure and function in sponge skeletal systems for over 20 years, and these species continue to amaze us,” Weaver emphasizes.
Through simulation and experimentation, the researchers replicated the design and compared the skeletal architecture of the sponge to the existing lattice geometry. The sponge’s design has outdone them all, withstanding heavier loads. The researchers showed that the paired parallel cross-diagonal structure improved the overall structural strength by more than 20 percent, without the need for additional material to achieve this effect.