The traditional PZT, however, is not the ultrasonic source with high efficiency because of the serious non-coupling phenomena between air and ordinary piezoelectric material.

Analysis of error source in the measurement can help to find the way to eliminate error. Accordingly the ultrasonic thickness measurement can adapt well to the measurement of artillery body.

The acoustic source of plane circular pistons with the radiating transient pulse wave finds wide application in the ultrasonic inspection and test.