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Validation of a Lamb wave-based structural health monitoring system for aircraft applications

Structural Health Monitoring technologies have the potential to reduce life-cycle costs and improve reliability for aircraft. Previous research conducted by the Metis Design Corporation has demonstrated the ability of Lamb wave methods to provide reliable information regarding the presence, location and type of damage in coupon-level specimens. Several critical system components have been developed during the course of this research, including circuitry and packaging, and integrated into the Monitoring & Evaluation Technology Integration (M.E.T.I.) Disk. In order to demonstrate the validity of M.E.T.I.-Disks for aircraft applications, a testbed has been fabricated by dividing a 1/8" plate of aircraft-grade aluminum into four equal quadrants with several c-channels. M.E.T.I.-Disk nodes were then placed in the center of each quadrant, and data was collected and interpreted by the METISv2.10 software package. The results produced by this software validated the M.E.T.I.-Disk by using a single undamaged cell to calibrate the system, and then correctly identify that there was no damage present in the remaining quadrants. Next, representative damage was introduced into several combinations of the quadrants, and the software was executed again to query the structure. The resulting data revealed the presence and location of damage, while still identifying the two undamaged regions.