Papers by Keyword: Time Reversal Technique

Abstract: Ultrasonic phased array inspection has been paid a great attention in ultrasonic nondestructive evaluation since it can provide a benefit of focusing and/or steering ultrasonic beams. A time reversal technique is claimed to be very robust to focus beams through inhomogeneous media, using the phased array transducers. In this paper, the performance and limitations of a D.O.R.T. method, which is one of the time reversal techniques, is considered based on the experimental studies. In addition, a variation of the D.O.R.T, namely a pre-focused D.O.R.T., is proposed in order to overcome the limitations of the current D.O.R.T. method. The results of the newly proposed method are compared to those obtained by conventional focusing methods.

Abstract: For the long range inspection of structures in nuclear power plant using array transducers, it is necessary to focus waves on defects under interrogation. To take care of such a need, in this study we adopt a time reversal technique that is claimed to be very robust to focus ultrasonic waves on defects. Specifically, we calculate the appropriate time delay using the time reversal technique and re-generate ultrasonic guided waves that are focusing to an interrogated defect with the calculated time delay. In this paper, we describe the principle of the time reversal technique briefly and present the performance enhancement obtained by the time reversal techniques.