The Electro-Mechanical Impedance Method for Damage Identification in Circular Plates

Among structural acoustics methods, the electro-mechanical (E/M) impedance method is a new method that is easy to implement on complex structures with minimum instrumentation and straightforward results. This new acoustic method benefits from the advent of commercially available low-cost piezoceramics that have opened new opportunities for structural identification. The structural dynamics is identified by obtaining the E/M impedance or admittance signatures of piezoelectric active sensors that are permanently attached to the structure. In presented study, the E/M impedance method was used to identify the structural dynamics and the presence of damage in circular plates. An analytical expression, which accounts for both axial and flexural vibrations of a plate, was derived and validated through a set of experiments. The experimental results show good matching with the theory. Additional acoustic experiments were conducted to assess the presence of damage in circular plates for particular set of boundary conditions. Some damage metrics were suggested to analyze the frequency spectrum obtained. The results show the changes in the E/M impedance spectrum due to damage presence. Future research will focus on application of the E/M impedance to the acoustical diagnostics of aging aircraft structures.