Development of an Automated Eddy Current Structural Health Monitoring Technique with an Extended Sensing Region for Corrosion Detection

The process of performing nondestructive evaluation (NDE) on a structural system is a well developed and continuously growing field. One very prominent method of performing NDE on a structure is through the use of eddy currents. Eddy current NDE methods are commonly applied to aircraft during maintenance checks in order to identify the formation of cracks, corrosion, or degradation of rivets. Structural health monitoring (SHM) takes NDE a step further and is a process of periodically or continuously monitoring and assessing the performance and safety of a structural system based on data obtained from a sensing system integrated into the structure. Here a method of integrating an eddy current sensing system into the structure such that the structure can be remotely monitored in an automated way is developed. The development of this sensor technology is novel because it can be automated and has a sensing region far larger than the sensor footprint. While earlier studies have integrated eddy current NDE sensors into various structures, all of these studies have developed sensors that can only detect damage directly under the sensor location, which makes SHM of the structure unrealistic. The eddy current senor is demonstrated to identify both corrosion and damage in the form of a small hole well outside the sensors footprint. Furthermore, the statistical variation in the measurements is shown to be very small making the ability to distinguish real damage from false predictions.