Engineers are taking design tips from an ‘uncrushable’ beetle.

The diabolical ironclad beetle (Phloeodes diabolicus) has an exoskeleton that is so tough, the insect can survive being run over by a car. 

A team of engineers in the US has mimicked some of the jigsaw-shaped joints found in the beetle’s anatomy with plastics and metal, and found their beetle-inspired creations are considerably tougher than a commonly used engineering joint used in the aerospace industry.

The diabolical ironclad beetle cannot fly away from danger, as its wings have evolved into crush-resistant exoskeletal forewings (called elytra), which means that it is able to withstand virtually any crushing and piercing strikes from predators.

In fact, its incredible strength has been a major challenge for entomologists, who cannot use standard steel pins to mount the beetles in display cases. 

Researchers at the University of California have studied the structural features and material composition of the elytra.

They found the beetle can withstand forces of up to 149 newtons, or about 39,000 times its body weight.

Using advanced microscopy, spectroscopy and mechanical testing, the authors observed a series of interlocked jigsaw-shaped joints at the middle of the elytra. They found that the geometry of these blades and their laminated microstructure provide excellent mechanical interlocking and toughening of the exoskeleton.

The team was then able to test the potential of this geometric structure as a mechanical fastener for joining different materials (such as plastics and metal), similar to that required in turbines in the aerospace industry.

They constructed a series of joints made of metal and composites that mimic the structures observed in the beetle. They found that their designs provided enhanced strength and significantly increased toughness compared to the engineering joint normally used in this scenario.

The study is accessible here.