This paper presents an experimental and theoretical investigation of the applicability of the time-reversal concept to guided waves in plate-like structures, where the stress waves are dispersive and of multi-modes. It is shown that temporal and spatial focusing can be achieved through time reversal, although the dispersive behaviour of the flexural waves renders it impossible to exactly reconstruct the waveform of the original excitation. Based on the principle of the time-reversal concept, a digital imaging method suitable for distributed sensor/actuator networks has been developed. This new method, which overcomes the limitation of the conventional phased array method that operates under pulse-echo mode, provides an efficient imaging method for locating and approximate sizing of structural damages. In addition, it has been shown that signal strengths can be considerably enhanced by applying the present synthetic time-reversal method, thus reducing the number of sensors and actuators required to achieve a given signal-to-noise ratio.

In this paper an experimental and theoretical investigation of the applicability of the time-reversal concept to guided waves in plates, where the waves are dispersive and of multi-modes. It is shown that although temporal and spatial focusing can be achieved through time reversal, the dispersive behavior of the flexural waves renders it impossible to exactly reconstruct the waveform of the original excitation. Nevertheless, the temporal and spatial focusing allows the development of a synthetic time-reversal array method for a distributed network of sensors and actuators. This new method, which overcomes the limitation of the conventional phased array method that operates under pulse-echo mode, can considerably enhance the signal strength, thus reducing the number of sensors and actuators required to achieve a given signal-to-noise ratio.