by Tom Nelligan
1. Basic Theory: Sound waves are simply organized mechanical vibrations traveling through a medium, which may be a solid, a liquid, or a gas. These waves will travel through a given medium at a specific speed or velocity, in a predictable direction, and when they encounter a boundary with a different medium they will be reflected or transmitted according to simple rules. This is the principle of physics that underlies ultrasonic flaw detection.
There are five types of ultrasonic transducers commonly used in flaw detection applications:
Complete list of Olympus NDT Flaw Detection Application notes.