Re: Ultrasonic beam profiles for angle probes in steel
Thanks to everybody for the comments on my question. Yes indead my main aim it to calculate beam spreads for angle probes prior ordering any specific probes for a job. If I can reasonably accurately calculate the 6dB angles, I can predict my inspection coverage and thus design an optimum technique. For example if I am required to detect small smooth planar flaws orientated at between 50 and 80 degrees of tilt (from the vertical), I can use beams of 15, 25 & 35 degrees if I have probes with a 6dB beam spread of +-5 degrees from nominal. This will give complete coverage of all expected defects within 5 degrees of normal, and a good response without relying on tip diffracted signals.
The difficult thing is the beams are not symetric after passing through the wedge, and crystals can be circular (or half moon), rectangular, or twins with a roof angle (or toe-in to those in the motor trade).
----------- Start Original Message ----------- : Does anybody know the best way to estimate 6db and20dB beam edges for angle probes. I have tried 2 different methods, and do not know which is best. : 1)calculate divergence angles in wedge material, and then using snells law calculate new refracted angles in steel test material : 2)calculate "equivalent crystal size" and use this to calculate divergence angles in steel test material. : I can email excel sheet if interested in calcs ------------ End Original Message ------------