A tiny animal inspires giant dreams
September 13, 2015
While evolution has granted humans any number of impressive skills, generating super-strong materials with our bodies isn’t one of them. For many of our fellow creatures, however, producing substances that withstand powerful external forces is simply business as usual. Spider silk, stronger than steel on a pound-for-pound basis, can resist winds of close to hurricane-force strength. Abalone shells absorb extraordinary impacts without fracturing.
Fantastic as these features may be, scientists at the University of Portsmouth recently announced that the teeth of the humble limpet, a tiny vegetarian mollusk, are even more impressive.
Allowing limpets to move across rock surfaces and remove algae to feed on, the teeth may be the strongest biological material known to man, the researchers claim.
The discovery has exciting implications for the built environment, raising the possibility of a new generation of supersized structures.
Stronger, longer, taller
Limpet teeth offer a much higher strength-to-weight ratio than steel and concrete. If scientists could replicate the material in the lab, builders would be able to create much longer bridges and taller towers.
How much longer and taller? Engineers Tom Wilcock and Mark Bowers in Arup’s New York office ran the numbers to find out how limpet-inspired structures would compare to existing megaprojects.
Consider the longest-spanning bridge in the world, Japan’s 1.2-mile-long Akashi Kaikyo Bridge. Today, bridge spans are limited by the need to keep suspension cables below the size at which they begin to sag under their own weight. Because limpet tooth cables could achieve equivalent strength using far less material, this would no longer be a concern. As a result, bridges could span a staggering 13.7 miles — enough to cover the Strait of Gibraltar with ease. With two spans, the limpet bridge could cross the Bering Strait to connect the United States and Russia.
Building heights could also increase dramatically. The highest structure in the world, Dubai’s Burj Khalifa, could in theory be 6.5 times taller, soaring a dizzying three miles into the air.
Large observation wheels could also be pushed well beyond their current limits. Standing 550 feet tall, the Las Vegas High Roller is currently the world’s biggest. A limpet tooth-inspired material could make a 2,198-foot-tall observation wheel a reality, dwarfing New York’s Empire State Building.
While strength is critical, engineers must also take many other factors into account when designing structures of such extreme proportions. Because limpet teeth are relatively flexible, these mega-bridges and buildings would need to be stiffened through the use of composite materials or mechanical damping devices.
Elevator technology would also need to advance beyond its current state. Today, the world’s fastest elevator would need almost five minutes to travel to the top of the limpet tower. And the ride would be dangerous as well as tedious. Without acclimatization, humans pass out at around 15,000 feet, meaning that only seasoned climbers could remain at the top without a breathing apparatus.
These structures may seem fanciful, but they illustrate the critical role that materials play in engineering and architectural design. By partnering with material scientists, architects and engineers may one day take structures to places we can only dream of today.