The Ultrasonics concepts as applied for testing activities are clearly broken down and expained, to easy the understanding. It is related to real life situations that makes the science to be implemented right away. I like it
good lecture... could you make a video for piezoelectric generator that produce pressure wave with high voltage... like the basic things to be considered... thanks
10:20 Why is the signal of the flaw echo weaker than the backwall echo at that graph when the distance to the flaw is much shorter? May this be because the flaw might not be 100 % parallel to the surface where the signal was started? So if the flaw has an angle for example?
The flaw may be very small, depending on the gain you have added into the calibration and the dac(tcg). The backwall is (almost) always there, it will send back more signal than the flaw, unless the flaw is large enough to block a lot of sound from reaching the bw.
I would say that depends on the frequency which is used by the ultra sonic device for testing your plate. The higher the frequency, the better is the precision and thus the smaller the thickness can be.