We always tend to see sea sponges as something soft and supple. A glass sponge, for example, looks like a vase or a beautiful glass sculpture, but don’t let its fragile appearance fool you, its structural structure is very strong.
This prompted Harvard John A Paulson for Engineering and Applied Sciences SEAS researchers to simulate the glass structures of marine sponges to design the next generation of stronger and taller buildings as well as long bridges and lighter spacecraft.
Flexible and sturdy structures
According to a paper published in Nature materials on September 21, the square-shaped structural construction of the Euplectella aspergillum, deep-sea basket sponge has the highest strength-to-weight ratio of any conventional grid design. Others, which have long been used for the construction of buildings and bridges for centuries.
Matthews Fernandez, a graduate researcher and first author of the study, explains their findings in the statement posted on the Harvard College page, saying, “We can reconstruct more robust and resilient structures by carefully rearranging the materials within the spongy structure.”
He adds, “Our results found that the strategy of reinforcing the diameter of the sponge achieved the highest rates of dent resistance, after we tested it on a specific amount of the material.”
And denting is a form of mechanical defect that occurs to the concrete components following earthquakes or exposure to excessive stress, then the components of that concrete material do not bear this extra amount of stress and begin to collapse.
James Weaver, a senior scientist at Harvard University and one of the authors of the paper, comments, “The force-to-weight ratio is one of the most important structural design criteria in many fields, such as aerospace engineering, and this nature-inspired engineering can provide a roadmap for designing lighter structures. Weights, more powerful, and has many applications. “
Spliced structural bundles
From bridges to storage shelves, engineering constructions rely on diagonal lattice structures. These designs use many small, spaced radial beams close together, to evenly distribute the loads on them.
This engineering idea was patented in the early 19th century in the name of the architect Ethel Ton who wanted a way to create durable bridges from lightweight and cheap materials.
“Ton has developed a simple and less expensive way to install square lattice structures that are used to this day,” Fernandez explains. “Although they serve the purpose, they are not perfect and cause waste of materials, and are limited to a certain height that cannot be exceeded.”
“This prompted us to ask: Is it possible to make these structural structures more efficient by using less materials that ultimately achieve the same degree of strength?”
Sponge is more efficient and strong
Fortunately, the answer was hidden in the glass sponge – a group of sponges that the Venus Flower Basket Sponges belonged to – that has inspired research and development.
In order to reinforce its tubular body, this type of sponge uses two types of parallel diagonal structural supports, which intersect and unite to form a square grid as a strong foundation for a chessboard-like structure.
“These types of sponges still fascinate us a lot,” says Weaver, who has studied shape-function interconnections in many spongy structures for more than 20 years.
By experimenting with this type of sponge, simulating it with reality, and comparing its structural composition with many of the currently existing grid-shaped engineering designs, the scientists observed the superiority of the engineering design of the sponge under study in all of them, as this type of sponge was able to bear heavy weights without any dent.
The scientists also indicated that the double and intersecting structure in parallel has enhanced the structural strength of this type of sponge by more than 20% without the need to add other materials to achieve this effect.
Katia Bertoldi – a professor of applied mechanics at Harvard University who is participating in the study – believes that “the study of sponge structures will enable us to construct anti-dent engineering buildings, which will have several important implications for improving the use of materials in modern infrastructure applications.”