There's nothing more frustrating than getting home from the store to find a huge dent in the side of the car and having no idea when it happened. But imagine if your car could feel pain, so to speak, and alert you when it takes damage. The US Army is funding research to make that kind of system a reality, and in future vehicles could be outfitted with a smart material that senses damage the way nerves sense pain and relay a damage report to help with maintenance and repairs.

Previous work has developed pain-like systems for robots, allowing them to sense damage of different severities and react accordingly to protect themselves. This new project, conducted by scientists at Clemson University and funded by the US Army Research Laboratory, would carry the same idea across to vehicles like helicopters, trucks and tanks.

The key to these "nerves" is a magnetostrictive material, which means it responds to changes in a magnetic field or physical stress. This material is sandwiched between several layers of composite materials, and by outfitting vehicles with these panels, the system would be able to sense damage like impacts, cracking and unusual loading. Then, a damage report can be forwarded to a computer that determines how bad the damage is and whether or not the vehicle should return to the depot.

"In the field, we need that self-diagnostic capability," says Oliver Myers, researcher on the project. "Lieutenant Data in Star Trek always says, 'I'm performing to specified parameters.' We want to make sure our platforms are performing to those specified parameters at a minimum."

The researchers say that embedding the damage sensors into the material makes them less cumbersome than adding sensors after the fact. It also means they don't need power, won't weigh a vehicle down and are protected from the elements.

The smart materials can also streamline the repairs and maintenance process. Wear-and-tear doesn't always show physically, so as a safety precaution the Army often replaces certain parts after a certain amount of time, whether or not they look like they need to. Building these kinds of sensors into them can allow people to easily tell if a part needs replacing or not, saving the time, cost and effort of throwing out parts that still have some life left in them.

The Clemson team has received almost US$1 million from the US Army Research Lab to develop the material, which could still be 10 to 20 years away from the field, according to the team.