MEASURING THE THICKNESS OF THE FAMOUS ANCIENT "GREAT BELL" IN BEIJING WITH ULTRASONIC METHOD

The thickness of the famous ancient "Great bell" in Beijing was for the first time measured with ultrasonic method. In the measurement, practical difficulties were overcome by using the pulse overlap method with alternative triggering, and adequately adjusting the radio frequency of transmitted ultrasonic pulse waves. The accuracy was about 1.5%. Including its hookup, the over all weight of the "Great bell", 46.6±1 ton, was calculated from its measured dimensions and density.