During straight beam testing, test specimens with non-parallel front and back surfaces can cause which effect?

During straight beam testing, test specimens with non-parallel front and back surfaces can cause which effect?

• A. Partial or total loss of back reflection
• B. A focused (narrow) back reflection indication
• C. No loss in back reflection
• D. A widened (broad) back reflection indication

Answer: (A)

When using straight-beam ultrasonics, the back-wall echo depends on the reflection returning directly to the probe along a straight path. If the front and back surfaces are not parallel, the back reflection is deflected away from the transducer or scattered, so the echo amplitude at the receiver drops and can even disappear. This is why non-parallel surfaces often cause a partial or total loss of back reflection. A focused or narrow back reflection would require specific, well-aligned geometry, which non-parallel surfaces do not provide. Likewise, a widened back reflection would imply the echo is spread but still reaching the probe, which is not the typical outcome here—the common effect is loss of the back echo due to misalignment.

When using straight-beam ultrasonics, the back-wall echo depends on the reflection returning directly to the probe along a straight path. If the front and back surfaces are not parallel, the back reflection is deflected away from the transducer or scattered, so the echo amplitude at the receiver drops and can even disappear. This is why non-parallel surfaces often cause a partial or total loss of back reflection. A focused or narrow back reflection would require specific, well-aligned geometry, which non-parallel surfaces do not provide. Likewise, a widened back reflection would imply the echo is spread but still reaching the probe, which is not the typical outcome here—the common effect is loss of the back echo due to misalignment.