TIME-REVERSAL FOCUSING OF ELASTODYNAMIC SCATTERED WAVES FROM A CRACK IN A REVERBERATING ENVIRONMENT

Abstract

In this study, ultrasonic measurements and simulations are performed to show that the time-reversal imaging works well with the reverberating wave fields and hence useful for ultrasonic testings. In the experiment, ultrasonic echoes from an artificial crack in a T-joint specimen are measured. The measured waveforms are then time-reversed and re-emitted into a finite difference numerical model for the investigation of focusing in a reverberating environment. It is found as a result that the path of the scattered waves can be traced in the time-reversed field back to its origin though their presence is hardly recognizable in the original signals. Moreover, the scattering source can be located accurately in the reverse-time migration images, thus highly robust nature of the time-reversal focusing concept has been demonstrated in a ultrasonic testing context.