In immersion testing, which type of wave is typically used to inspect for defects when employing a shear wave approach?

In immersion testing, which type of wave is typically used to inspect for defects when employing a shear wave approach?

• A. Longitudinal waves
• B. Shear waves
• C. Surface waves
• D. Rayleigh waves

Answer: (B)

The essential idea is that the wave mode chosen in immersion ultrasonic testing determines what kinds of flaws you’re most sensitive to. When you’re using a shear-wave approach, you deliberately generate and use shear waves in the material. This is done by converting the waterborne wave at a boundary (often with a wedge) into a transverse wave inside the test piece at the proper angle. Shear waves have particle motion perpendicular to their direction of travel, which makes them especially responsive to cracks and planar defects that run parallel to the surface. The reflection and mode-converted signals from such flaws tend to be stronger or more distinct with shear waves, improving detectability. Surface or Rayleigh waves stay near the surface and aren’t as effective for revealing typical bulk defects, so they aren’t the chosen mode for this approach.

The essential idea is that the wave mode chosen in immersion ultrasonic testing determines what kinds of flaws you’re most sensitive to. When you’re using a shear-wave approach, you deliberately generate and use shear waves in the material. This is done by converting the waterborne wave at a boundary (often with a wedge) into a transverse wave inside the test piece at the proper angle. Shear waves have particle motion perpendicular to their direction of travel, which makes them especially responsive to cracks and planar defects that run parallel to the surface. The reflection and mode-converted signals from such flaws tend to be stronger or more distinct with shear waves, improving detectability. Surface or Rayleigh waves stay near the surface and aren’t as effective for revealing typical bulk defects, so they aren’t the chosen mode for this approach.