UT Testing-Section 2 Physics of Ultrasound

Application Case#1:
The specimen's geometry determines the number of its natural frequencies: a
rod has few whilst a complex work-piece has many such frequencies.
Typically, the information that can be obtained by acoustic resonance
analysis includes cracks, structural properties, cavities, layer separation,
chipping, density fluctuations etc. Damping behaviour depends firstly on the
material, and secondly, on how the specimen is positioned during its
excitation. In order to achieve high frequency resolution, signal duration
("ringing duration") should be as long as possible (> 50 ms).