What best describes a multi-echo signal in UT and its cause?

What best describes a multi-echo signal in UT and its cause?

• A. A single reflection
• B. A multi-echo signal from several interfaces; caused by surface roughness, layered materials, or misalignment
• C. Electrical noise
• D. Attenuation

Answer: (B)

In ultrasonic testing, a multi-echo signal happens when the transmitted wave encounters more than one boundary or interface, so the receiver picks up several distinct reflections rather than just one. This is why the signal shows multiple echoes: every interface with a change in acoustic impedance can reflect part of the wave back to the transducer. The causes for these multiple echoes include surface roughness, which scatters energy and creates extra small reflections; layered materials, where each interface between layers produces its own echo; and misalignment, which can redirect energy to strike additional boundaries or return along multiple paths, producing ghost echoes. These factors generate a series of echoes corresponding to the different interfaces, rather than a single clean reflection.

In ultrasonic testing, a multi-echo signal happens when the transmitted wave encounters more than one boundary or interface, so the receiver picks up several distinct reflections rather than just one. This is why the signal shows multiple echoes: every interface with a change in acoustic impedance can reflect part of the wave back to the transducer.

The causes for these multiple echoes include surface roughness, which scatters energy and creates extra small reflections; layered materials, where each interface between layers produces its own echo; and misalignment, which can redirect energy to strike additional boundaries or return along multiple paths, producing ghost echoes. These factors generate a series of echoes corresponding to the different interfaces, rather than a single clean reflection.