Real-time health monitoring of pipeline structures using piezoelectric guided wave propagation

The pipeline structure is an essential underground infrastructure that transports primary sources. Since most pipeline structures are placed underground and are connected to each other in a complex manner, it is difficult to monitor their structural health continuously. Recently, on-line and real-time structural health monitoring system was developed by the authors' research group to overcome the limitations of recent monitoring techniques. This paper presents a real-time pipeline health monitoring (PHM) methodology based on piezoelectric guided wave propagation method. Several damage cases of notch-type were produced artificially on the pipeline structures, and macro-fiber composite (MFC) sensors with piezoelectric characteristics were used to detect these damages. In particular, wavelet transform was applied to the guided-wave signals obtained from the MFC sensors to reduce the signal to noise ratio. For more generalized damage evaluation of pipeline systems, a damage metric based on Root Mean Square Deviation (RMSD) is computed from the de-noised wave signals to quantify the different level of the damage. Optimal threshold levels for decision making were estimated using a generalized extreme value-based statistical method. The effectiveness and robustness of the proposed PHM system were evaluated using a series of experimental studies.