A Modeling Approach to Interpret the Dispersion Relationship for Piezoelectric Sources

Guided wave techniques have great potential for the structural health monitoring of plate-like components. Previous research has demonstrated the effectiveness of combining laserultrasonic techniques with time-frequency representations to experimentally develop the dispersion relationship of a plate; the high fidelity, broad bandwidth and point-like nature of laser ultrasonics are critical for the success of these results. Unfortunately, laser ultrasonic techniques are time and cost intensive, and are impractical for many in-service applications. This research develops a complementary digital signal processing methodology that uses mounted piezoelectric elements instead of optical devices. This study first characterizes spatial and temporal effects of oil coupled and glued piezoelectric sources, and then develops a procedure to interpret and model (in the forward sense) the distortion caused by their limited bandwidth and finite size. These considerations give the background for further studies to develop the dispersion relationship of a plate having the fidelity and bandwidth similar to results provided with laser ultrasonics, but made using mounted piezoelectric sources.