Which ultrasound testing technique is used that relies on reflections from internal features?

Which ultrasound testing technique is used that relies on reflections from internal features?

• A. Pulse-echo
• B. Through-transmission
• C. Phased array
• D. Time-of-flight diffraction

Answer: (A)

In ultrasound inspection, signals that bounce back (echoes) from boundaries or discontinuities inside the material are what reveal flaws. A pulse is sent into the weld, and any internal feature such as a crack or inclusion reflects part of that energy back to the transducer. By measuring the return time and the echo’s strength, you locate and size the defect. This approach is the pulse-echo technique, where the same transducer both emits the sound and listens for the echo. It’s especially well-suited for detecting flaws within a weld from a single surface. Through-transmission, by contrast, uses separate transmitter and receiver on opposite sides; it detects flaws mainly by changes in signal transmission (attenuation) rather than discrete back-reflections, so it’s not based on reflections from internal features. Phased array can perform pulse-echo inspections with multiple elements, but the essence of relying on reflections from internal features points to the echo-based pulse-echo method. Time-of-flight diffraction relies on waves diffracted from crack tips, not straightforward reflections from internal features.

In ultrasound inspection, signals that bounce back (echoes) from boundaries or discontinuities inside the material are what reveal flaws. A pulse is sent into the weld, and any internal feature such as a crack or inclusion reflects part of that energy back to the transducer. By measuring the return time and the echo’s strength, you locate and size the defect.

This approach is the pulse-echo technique, where the same transducer both emits the sound and listens for the echo. It’s especially well-suited for detecting flaws within a weld from a single surface.

Through-transmission, by contrast, uses separate transmitter and receiver on opposite sides; it detects flaws mainly by changes in signal transmission (attenuation) rather than discrete back-reflections, so it’s not based on reflections from internal features. Phased array can perform pulse-echo inspections with multiple elements, but the essence of relying on reflections from internal features points to the echo-based pulse-echo method. Time-of-flight diffraction relies on waves diffracted from crack tips, not straightforward reflections from internal features.