Engineers at Purdue University have turned to nature for inspiration to create ultra-tough materials. Beetles may be small, but they are tough creatures that survive unthinkable situations, including getting eaten by frogs or surviving enormous crushing forces.
The diabolical ironclad beetle, Phloeodes diabolicus, has an exoskeleton so tough that it can survive getting run over by a car, and many predators don’t stand a chance of cracking one open. The Purdue team has uncovered details on how the ironclad beetle can endure such tremendous impacts, which they believe paves the way for new materials that bear similar indestructible characteristics.
The team observed the ironclad’s exoskeleton at work under high pressures through CT scans and compressive steel plates. It showed that the beetle could handle loads at least 39K times its body weight before fracturing, which is equivalent to an applied force of approximately 150 newtons or a person holding a stack of about 40 battle tanks.
The team then used microscopic images, computer simulations, and 3D-printed models to isolate the exoskeleton’s detailed structures. They found a tightly interlocked and impact-absorbing connective suture running along the length of the beetle’s abdomen.
While the ironclads lack wings, the suture lies between the beetle’s two wing cases, known as elytra. This suture connects the elytra with the exoskeleton blades that lie beneath them, helping to distribute pressure evenly across the beetle’s body via two complex mechanisms:
- The exoskeleton’s blades lock themselves into one another, like pieces of a jigsaw puzzle, which helps prevent it from getting jerked out of place under extreme force.
- The blades and suture divide into layers.
These findings could help make stronger bridges, buildings, body armor, vehicles, and gas turbines for aircraft, where composite materials and metals are combined using heavy mechanical fasteners that cause stress and fracturing over time.
The engineers conducted loading tests using a custom-built carbon fiber composite fastener based on the ironclad’s exoskeleton structure. The results showed that it was just as strong and significantly tougher than existing aerospace fasteners.
Pablo Zavattieri, an author of the study, said:
This work shows that we may be able to shift from using strong, brittle materials to ones that can be both strong and tough by dissipating energy as they break. That’s what nature has enabled the diabolical ironclad beetle to do.
The Purdue team published their findings on October 21 in the journal Nature, while an overview of the research is demonstrated in the video below.
