A conceptual study on guided wave based imaging techniques for SHM with distributed transducer arrays

The combination of an array of distributed transducers permanently coupled to the structure under investigation and the possibility to compare the actual state of the structure with a predefined reference state offers totally new perspectives for elastic wave based signal processing and imaging techniques. In the present paper a multi-level approach for the evaluation of guided elastic wave data obtained by an array of distributed sensors and actuators is presented. For this purpose a numerical simulation platform has been developed that allows extensive 3-D calculations of guided wave propagation including appropriate signal processing and data evaluation algorithms. Calculations in a quasi-isotropic plate are used to exemplary demonstrate various imaging approaches. The results reveal that imaging techniques based on distributed transducer arrays are able to increase the significance of monitoring results and should therefore lead to a considerably better performance and enhanced acceptance of guided wave based SHM systems in the near future.