关键词: 超声导波, 单探头, 杆, 时间反转法, 无损检测

Abstract: Time reversal method using single transducer for rod nondestructive test with guided wave is presented. It can efficiently improve defect resolution and expand the inspection frequency bandwidth. Single transducer mounted on the end of rod is excited by narrow band signal of different center frequencies in a wide frequency range to generate ultrasonic guided wave. Defect signals included in the echo signal are operated with a time reversal procedure and used as exciting signal again. Thus the resolution of defect inspection is improved for the time-space compression property of time reversal method. Experiment results show that dispersion of echo signal from defects is limited and amplitude is increased in the frequency with greater dispersion. Source signal is efficiently reconstructed in the frequency with smaller dispersion so that signal noise rate is improved. In the multi-time reversal inspection, defect signal show the phenomenon of dispersion-compression-dispersion, which illustrate that only once time reversal procedure is needed when using signal transducer for defect detection.

Key words: Nondestructive test, Rod, Single transducer, Time reversal method, Ultrasonic guided wave