Flaw Detection in Aluminum Welds by the Electric Current Perturbation Method

The integrity of the Space Shuttle external fuel tank is vital to the success of each shuttle mission. These giant tanks (154 ft long and 28 ft diameter) are manufactured for NASA by Martin Marietta Aerospace, New Orleans, LA. An important part of the quality assurance for each tank is detection of defects in the welds using nondestructive evaluation (NDE) methods. The tank is manufactured from aluminum panels which are welded together, and due to the large physical size of the tank, several thousand feet of weld must be inspected for each tank. Therefore, to be cost effective, the NDE methods used must not only be reliable but also must be rapid