What does “mode conversion” mean in phased array ultrasonic testing?

In phased array ultrasonic testing, "mode conversion" refers specifically to the process of changing wave modes at material interfaces. When ultrasonic waves travel through different materials, they can change from one type of wave to another, such as from longitudinal waves to shear waves. This phenomenon is significant because it affects the way sound waves propagate and can influence the effectiveness of the testing.

Understanding mode conversion is critical for interpreting inspection results accurately, as different wave modes can have distinct characteristics and may respond differently to flaws in the material. By recognizing and accounting for these changes in wave mode, technicians can create a more precise and effective ultrasonic testing strategy.

The other options do not accurately capture the essence of mode conversion. The constant frequency of the waves pertains to the specific design of the transducers, whereas the amplitude relates to the strength of the sound waves rather than their mode. Lastly, the number of transducers used is more about the configuration of the phased array system rather than the interaction of waves at material boundaries.