Electromagnetic Smart Washer for Detecting Bolthole Cracking

Engineers have designed a new device, called the Smart Washer, that can electromagnetically detect bolthole cracks in metal structures. The device is a metal washer that contains a wire coil embedded onto the bottom surface of the washer. An alternating current drives this coil and induces eddy currents around the bolthole. These eddy currents develop electromagnetic fields that interact with the driving field of the coil.