Simulation of PZT electrical signals under the action of sound field in ultrasonic inline inspection of pipelines

The precise correlation between the pipeline defects and inspection signals is a key issue in the analysis of echo signals in ultrasonic inline inspection. However, the sensitivity of acoustic and electric signals in the transmission, propagation, and reception during the inspection brings great challenges to this problem. Analyzing the direct piezoelectric effect of Lead Zirconate Titanate(PZT) through numerical simulation is an effective way to study the characteristics of the inspection signals. Therefore, a finite element analysis model of the probe was established with the COMSOL software, the echo data were extracted from the simulation results of sound field in the probe array as the initial excitation load of the model for simulation, and the accuracy of the finite element model was verified by comparing with the experimental results of ultrasonic inline inspection. The results show that: The error between the simulation result and the measured data of the ratio of the maximum peak values of the surface echo and the primary bottom echo is 1.36%, indicating that the new model has a relatively high accuracy. The defect depth of the inner wall surface has a significant influence on the amplitude of the second peak in the PZT electrical signal spectrogram, and an effective correlation can be established between them. In addition, based on the simulation results of electric signals, the maximum valley point of the surface echo and the maximum peak point of the primary bottom echo can be extracted in the time-domain diagram of echo as the characteristic points, and the maximum error of the inspected pipeline wall thickness is 3.95%. Generally, the research results could provide reference for the localization of ultrasonic inline inspection tools.