10D-2 Integrated Plate Acoustic Wave Transducers Using Mode Conversion

Integrated (IUTs) and flexible ultrasonic transducers (FUTs) have been used to generate and receive plate acoustic waves (PAWs) for long distance (up to more than lm) structural health monitoring applications. These IUTs and FUTs were made by sol-gel spray techniques and thickness vibration longitudinal wave transducers. Using mode conversion techniques these transducers located at the edges of the plates could excite and detect symmetrical, anti-symmetric and shear horizontal types of PAWs in pulse/echo mode. IUTs were directly deposited and FUTs were glued onto the edges of the plates. In 2 mm and 6.35 mm thick plates line defects of 1 mm width and 1 mm depth were clearly detected at temperatures up to 150degC. Results indicated that for 2 mm thick aluminum plates shear horizontal PAWs were the best for the line defect detection.