What is the major difference between acoustic emission testing (AET) and other NDT techniques?
The main difference between Acoustic Emission Testing (AET) and other Non-Destructive Testing (NDT) methods is that AET listens for natural sounds from within the material to find damage as it happens, even over large areas. Other NDT methods use external signals to find defects, giving precise details but usually needing direct access to the area being tested.
First let us try to understand the difference between Acoustic Emission Testing (AET) and Ultrasonic Testing (UT). In AET, transient elastic energy generated by the defect in the material or component is being received by the appropriate transducers and analyzed and accordingly the defect is qualified/ quantified and its source is identified. AET transducers are usually broad band transducers. Whereas in UT, ultrasonic waves certain peak frequency (usually narrow band) is being produced first by the transducer and sent into the direction of the defect in the material or component. Then the reflected ultrasonic energy is being received by the same transducer and analyzed for qualification or quantification of that defect in pulse-echo technique. In through transmission UT, the reflected, refracted and transmitted waves by the defect is being received by other one or more transducers and analyzed for the qualification or quantification of that defect. Hence the basic difference is that AET make use of the generated acoustic signals from the defects whereas in UT generated ultrasonic waves are being sent and received and analyzed for defect quantification/ qualification.
Kindly note that the term “acoustics” is a general one and that constitutes all frequencies including sub-sound, audible sound, ultrasound of all frequencies.
Likewise the difference between AET and X-ray Diffraction Technique (XRD), Eddy Current Technique (ECT), etc. could also be explained.
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