Ultrasonic-GW Tomographic Analysis and Probabilistic Reconstruction Approach for SHM Applications

We present a structural health monitoring (SHM) paradigm based on the active generation, detection, and processing of guided ultrasonic waves (GUWs). The paradigm is tested on an aluminum plate instrumented with an array of six piezo-wafer transducers. These transducers are part of a unified SHM system where the non-destructive evaluation technique of acoustic emission, electromechanical impedance, and guided ultrasonic waves are integrated in the same hardware/software unit. In the study presented in this paper, we analyzed the ultrasonic data using a tomographic and a probabilistic reconstruction algorithm based on different reconstruction techniques and/or several damage ultrasonic parameters analysis. The objective is to enhance the detection and localization of damage that, in this study, consisted of a permanent magnet attached to the plate. The damage is, therefore, represented by a small mass added to the plate. The results presented here show that the tomographic reconstruction algorithm is robust and can be integrated into the unified SHM system to reduce false positives/negatives. A comparison with a probabilistic reconstruction algorithm is also presented.