In immersion testing, the standard method to generate shear waves relies on angulating the transducer to the proper angle. True or false?

• A. True
• B. False
• C. Not applicable
• D. It uses resonance

Answer: (D)

In immersion testing, shear waves are generated by using an angled transducer (angle-beam technique) to cause mode conversion at the water–material interface. When the longitudinal wave in water hits the boundary at a specific oblique angle, part of the energy converts into a shear (S) wave inside the material. The transducer angle, often set with a wedge, selects the direction and path of the shear wave present in the test piece, and Snell’s law governs how the wave modes refract into the material. This is the standard method because it reliably produces a shear wave with the desired orientation for flaw detection.

Resonance, while related to how a transducer is driven, is not the mechanism used to generate shear waves in immersion UT. The generation of shear waves relies on the mode-conversion at a chosen incidence angle, not on exciting the transducer at its resonant condition to create the shear wave directly.