Understanding Acoustic Emission Testing- Reading 1 Part B-A

Wave Mode and Velocity
As mentioned earlier, using AE inspection in conjunction with other NDE
techniques can be an effective method in gauging the location and nature of
defects. Since source locations are determined by the time required for the
wave to travel through the material to a sensor, it is important that the velocity
of the propagating waves be accurately calculated. This is not an easy task
since wave propagation depends on the material in question and the wave
mode being detected. For many applications, Lamb waves are of primary
concern because they are able to give the best indication of wave
propagation from a source whose distance from the sensor is larger than the
thickness of the material. For additional information on Lamb waves, see the
wave mode page in the Ultrasonic Inspection section.
Charlie Chong/ Fion Zhang