Which best describes a typical display of a crack whose major surface is perpendicular to the ultrasonic beam?

Which best describes a typical display of a crack whose major surface is perpendicular to the ultrasonic beam?

• A. A sharp indication
• B. A broad indication
• C. The indication will not show due to improper orientation
• D. A broad indication with high amplitude

Answer: (A)

When a planar flaw is oriented so its major surface is perpendicular to the ultrasonic beam, it acts like a small, flat reflector facing the transducer. The incident waves reflect back in a fairly uniform, specular manner, so the echo returns as a single, strong, narrow pulse. On the display this shows up as a sharp indication at the depth corresponding to the crack location. If the crack were oriented parallel to the beam, the reflection would be less like a focused mirror and more spread along the crack front, producing a broader, longer-lasting signal that is often less intense. If the orientation prevents an effective reflection, you might see little or no indication at all. So the best description for a crack whose major surface is perpendicular to the beam is a sharp indication.

When a planar flaw is oriented so its major surface is perpendicular to the ultrasonic beam, it acts like a small, flat reflector facing the transducer. The incident waves reflect back in a fairly uniform, specular manner, so the echo returns as a single, strong, narrow pulse. On the display this shows up as a sharp indication at the depth corresponding to the crack location.

If the crack were oriented parallel to the beam, the reflection would be less like a focused mirror and more spread along the crack front, producing a broader, longer-lasting signal that is often less intense. If the orientation prevents an effective reflection, you might see little or no indication at all.

So the best description for a crack whose major surface is perpendicular to the beam is a sharp indication.