What defines a shear wave used in ultrasonic testing?

The definition of a shear wave used in ultrasonic testing is characterized by how these waves propagate through the material. Shear waves, also known as S-waves, are a type of mechanical wave that moves through materials by causing particles to move perpendicular to the direction of wave propagation. This is crucial because it helps in detecting subsurface flaws within a material that might not be visible through other means.

When shear waves are sent at an angle between 45 and 60 degrees, they can be particularly effective for testing various materials because this range optimizes the interaction with flaws within the material structure. This angle allows the waves to reflect off internal discontinuities, thus helping the technician identify issues such as cracks or voids that could affect the integrity of the material.

In contrast, sound waves that move parallel to the material are known as longitudinal waves, which primarily detect surface flaws rather than subsurface issues. The requirement for training in ultrasonic testing is also significant, as operators need specific skills to interpret the results correctly, demonstrating that ultrasonic testing necessitates trained professionals. Therefore, the definition of shear waves is distinctively aligned with their angle of propagation and their role in detecting subsurface flaws.