Numerical Simulation And Experimental Study On Defect Detection For Pipe Structure Using PZT-based Wave Method

With the rapid development of economy,the demand for petroleum,water,natural gas and other resources increased rapidly.And the unique advantages of pipelines in the transport of liquids and gases make them playing a more and more important role in economic construction.However most of the pipelines are facing relatively poor working environment,pipelines,especially steel pipelines,are prone to corrosion and cracks,and other kind of defects initiat.These defects lead to reduction of reliability and safety of pipeline transportation,and even lead to leakage and explosion accidents.Therefore,efficient defect detection approaches is critical.By using guided wave measurement based on piezoelectrics array,a defect detection approach for pipeline is proposed and verified,numerically and experimental.The major contents of this study are as follow:Firstly,by studying the relative theory of piezoelectric materials and health monitoring based on piezoelectric,combined with the characteristics of pipeline health monitoring,reasonable piezoelectric material is selected,and the composition and arrangement of the monitoring system are determined.Secondly,by studying the basic theory of guided waves,and according to the characteristics of guided wave in pipeline,combined with the dispersion equation,the dispersion curve of pipeline was solved.Based on the pipeline model used in the numerical simulation and experimental study,and the dispersion curve of the model,the best excitation electrical signal was chosen.Thridly,using the finite element software ANSYS to simulate longitudinal guided wave and torsional mode guided wave excited by PZT to defect the pipeline defects.Numerical simulation on the guided wave propagation of different pipes with various cracks excited by PZT actuators at one end of each pipe is carried out.the echo signal is measured by PZT sensors at the receiving end.By analyzing the time history signal and establishing a damage index,the location of defects is determined.Finally,the pipeline models with different defects are designed,and piezoelectrics paches bonded on the surface of the pipe are used as the actuators and sensors to measuer the response under different excitation signals.According to the time history signal of the sensors under pulse excitation signals,the feasibility and sensitivity of the pipeline defect detection using piezolelctric patches are illustrated.