Finite Element Analysis Of Defect Detection On Insulated Pipes Based On Pulsed Eddy Current

Flammable and explosive substances are transported by the pipe,the existence of defects on the pipe is a serious threat to the safety of lives and property.It's very difficult to detect defects on insulated pipe.In order to prevent the occurrence of major accidents,reduce the loss and cost caused by stripping clad layer and improve the detection efficiency,pulsed eddy current testing(PECT)is used for detecting defects on insulated pipes.The main research contents and conclusions are as follows:(1)The influence of tested materials,lifting height and clad layer in PECT is studied by establishing simulation model,which provides guidance for the optimization of probe and the analysis of signal.(2)By using the finite element method,the probe is optimized from the position of receiving coil,the radius and the aspect ratio of exciting coil,exciting frequency and duty ratio.The peak sensitivity of differential voltage on optimized model is increased by 12%,and the sensitivity of ratio is far greater than that before optimization.(3)Inner-wall or outside-wall defect PECT model is established by using the optimized probe,the eigenvalues of differential voltage are extracted,and taken to curve fitting in least squares and classify defects.The results show that: The eigenvalues have certain functional relations with the depth and radian of inner-wall or outside-wall defect model.Differential voltage peak and fundamental component of inner-wall defect model are less than that of outside-wall defects model,the peak time of inner-wall defect model is greater than that of outside-wall defects model.