Cracks in oil and gas pipelines cause leakage which results in property damage,\nenvironmental pollution, and even personal injury or loss of lives. In this paper, an active-sensing\napproach was conducted to identify the crack damage in pipeline structure using a stress wave\npropagation approach with piezoceramic transducers. A pipeline segment instrumented with five\ndistributed piezoceramic transducers was used as the testing specimen in this research. Four cracks\nwere artificially cut on the specimen, and each crack had six damage cases corresponding to different\ncrack depths. In this way, cracks at different locations with different damage degrees were simulated.\nIn each damage case, one piezoceramic transducer was used as an actuator to generate a stress wave\nto propagate along the pipeline specimen, and the other piezoceramic transducers were used as\nsensors to detect the wave responses. To quantitatively evaluate the crack damage status, a wavelet\npacket-based damage index matrix was developed. Experimental results show that the proposed\nmethod can evaluate the crack severity and estimate the crack location in the pipeline structure\nbased on the proposed damage index matrix. The sensitivity of the proposed method decreases with\nincreasing distance between the crack and the mounted piezoceramic transducers.
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