Sonic IR is a relative new nondestructive inspection technique developed to detect cracks in materials such as metals, polymers, ceramics and composites. This technique, while not yet accepted by industry as a standard, is gaining wide interest because it is fast and reliable, has low environmental and health impact, and is less prone to operator error compared to current practices. Our major finding over the past two years is that this technique causes fatigue cracks to propagate under typical operating condition. The reason for the observed crack propagation is due to the mismatch between the high power output from the source (an off-the-shelf equipment used for welding plastics) and the low power requirements for most inspection situations. We are therefore proposing to develop a new sonic IR instrument that can self-adjust to still allow for reliable inspection but will not further damage the component. Our proposed instrument would utilize commercial, off-the-shelf piezoelectric actuators on multiple locations (as opposed to a single, high-power actuator) as the vibration sources and drive them using a controllable power amplifier. The control system would be custom software that inspects the infrared camera's image to identify defects and interfaces with the amplifier for instrument control.
