Damage Detection in Thick-Walled Composites Using Surface Mounted Piezoelectric Elements

Strategic University Resources porposes to develop a method for detecting internal damage in thick-walled composite structures. The proposed real-time, nondestructive method will be convenient and fast enough to use for 100% inspection of parts prior to their placement in service. The proposed method is based on removable surface-mounted piezoelectric polymer patches that are able to detect delaminations or other internal damage by sensing changes in vibrational characteristics of the composite structure. The main goal of the proposed Phase I effort is to develop the method and demonstrate its ability to detect internal delaminations in composite walls one inch thick or more. The first step in meeting this goal is to establish the test configurations and procedures that best reveal changes in vibrational characteristics as a function of internal damage. This will be done with the aid of a series of thick-walled composites with various degrees of known internal damage. The second step in meeting the goal is to apply the method to composites with unknown damage and to verify the results by independent methods. The successful execution of Phase I will lay the groundwork for Phase II, which will be the standardization and automation of the method so it can be reliably used by semiskilled workers for quality inspection in the composite structure fabrication plant. In addition to its military applications, the proposed test method has potential applications in the area of civil engineering structures, and area of increasing importance as the nation's decaying infrastructure is replaced by large composite structures. The proposed damage detection method based on surface-mounted piezoelectric patches will make possible the rapid, 100% inspection of these thick-walled components.