There are many times that the natural world has shaped solutions to real-world engineering challenges (the Centre for Nature Inspired Engineering, part of University College London, researches this area specifically). Examples include the kingfisher’s beak for Japan’s bullet train, a termite’s mound for a building in Zimbabwe, and a humpback whale’s fin improving efficiencies in turbine blades.
With Spider-Man: Homecoming hitting the cinemas in the UK this week, we thought it would be a great opportunity to look at the fascinating engineering elements of the spider’s web, looking at both the material and structural components that make it so successful.
It’s no secret that the spider’s silk is an amazing material. It is up to five times stronger than steel of the same weight and has the ability to stiffen or soften dependent on the type of load, unlike any other natural or man-made fibre. Previously considered a weakness, research has shown this is an advantage when resisting damage.
As well as the silk, spiders also create a hybrid material for their webs that allows it to stay taunt. Any loose thread is spooled inside tiny droplets of glue and surround the core fibres of a web, effectively acting as a winch.
A team at the University of Oxford and the Université Pierre et Marie Curie used this knowledge to create composite fibres in the laboratory that extend like a solid but compress like a liquid.
It’s not just the material itself that is impressive, but also the structure of the web itself.
A spider’s web resists stress step-by-step. The thread initially stiffens and stretches and then sharply stiffens again to transfer the pressure to the rest of the web. After even more pressure is applied however, crystalline structures absorb the maximum strain and beak, creating localised damage but leaving the rest of the web intact.
Recent research has uncovered that when a single strand or two of the web breaks, the whole structure is actually strengthened rather than weakened. This is due to the structure of the web encouraging localised damage only, with areas of damage able to be repaired easily without affecting the integrity of the whole web or can simply be left alone for the web to continue to operate the same as before the damage occurred.
The fact that a spider’s web deals well with localised damage could influence the way we design things such as buildings in the future. For example, current earthquake prevention systems on buildings dissipate energy but when they fail, they fail in their entirety and cause the whole building to be collapse. A new approach where buildings flex and then allowing certain elements to break first could actually be more effective. This actually already happens in the automotive industry in the design of cars so that in the case of front-end crashes, localised failures take the forces away from the passengers.
Humans may not be able to run up walls like Spider-Man any time soon, but new findings could yield valuable engineering insights into a number of fields including structural engineering and bioengineering.
Current engineering approaches tend to focus on materials with uniform and linear responses because their properties are more predictable, but research into the spider’s web suggests there could be important advantages to materials whose responses are more complex.
This could be used to influence the design of new damage-resistant and super-strength materials and structures that are designed differently. Exciting future applications could be in areas such as artificial tissue and ligaments, body armour, and building materials.
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