Improvement in Crack Detection by Ultrasonic Pulse-Echo with Low Frequency Excitation

摘要

The results of studies to determine the feasibility of inducing stress in metal samples with low frequency excitation have indicated that the effective use of this technique is limited to excitation in the cyclic frequency range of 1000 Hz and below. Best results were obtained with solid coupling of low frequency exciters to test material. Attempts to induce stress with excitation at 20 kHz were not very successful with the techniques and equipment used in these studies. (Author)