Ultrasonic Testing Overview
Ultrasonic testing is an inspection method that uses high-frequency sound energy to conduct examinations and make measurements. It can be used for flaw detection/evaluation, dimensional measurements, material characterization, and many other applications. Although often performed on steel and other metals and alloys, ultrasonic testing can also be applied to concrete, wood, and composites, albeit with less resolution. This method is widely used in industries such as steel and aluminum construction, metallurgy, manufacturing, aerospace, automotive, and other transportation sectors.
Components of a Typical UT Inspection System
A typical ultrasonic testing (UT) inspection system consists of several functional units, including the pulser/receiver, transducer, and display devices. The pulser/receiver is an electronic device that produces high-voltage electrical pulses. Driven by the pulser, the transducer generates high-frequency ultrasonic energy. The sound energy is introduced and propagates through materials in the form of waves. When there is a discontinuity, such as a crack, in the wave path, part of the energy is reflected back from the flaw surface. The transducer transforms the reflected wave signal into an electrical signal, which is then displayed on a screen.
Advantages and Limitations of Ultrasonic Inspection
Advantages :
- Sensitive to both surface and sub-surface discontinuities.
- Superior depth of penetration compared to other non-destructive testing (NDT) methods.
- Requires access to only one side of the material when using the pulse-echo technique.
Limitations :
- Linear defects oriented parallel to the sound beam may go undetected.
- Requires more extensive inspector skills and training compared to other techniques.
- Difficult to inspect materials that are rough, irregular in shape, very small, exceptionally thin, or not homogeneous.