Which of the following can be sources of non-relevant ultrasonic signals?

• A. Surface Roughness of the Part
• B. Mode Conversion Within the Part
• C. Shape or Contour of the Part
• D. All of the Above

Answer: (D)

Non-relevant ultrasonic signals are reflections or responses that come from features of the part or setup that are not the flaw you’re looking for. Surface roughness can scatter the ultrasonic beam and create background echoes that mask or resemble flaws. Mode conversion inside the part occurs when the energy changes from one wave type to another at boundaries or interfaces, producing secondary signals at unexpected times or angles. The shape or contour of the part, including curves, thickness changes, or edges, can reflect or refract waves in ways that generate echoes unrelated to defects. Since each of these factors can produce signals not caused by flaws, the best choice is all of the above.