The Simulation Reasearch Of Detecting Defects In Pipe Using L(0,2)

These years, with the advantages of speediness, simpleness, long distance, the technology of detecting defects in pipe using guided waves was developped rapidly. In order to provide the guidance in actual detection based on guided waves, it is necessary to acquire the guided waves reflection characteristics from the defects of different types in different parts of the pipeline. By using ANSYS, the simulation research of detecting the crack and hole defects in straight and bent90°pipe by L(0,2) guided waves in this paper.According to the dispersion properties of guided waves in pipe, the L(0,2) is selected as defects detection mode in pipe. At first, The models established are proved to be correct through the compare the simulation result of defects detecting in outside surface of straight pipe by L(0,2) and experimental datas in related literatures. Then the models of straight pipe with crack in inner surface and hole defects are simulated. According to the displacement field features of propagating through the bent90°pipe by L(0,2), the bend was divided into three areas. The simulation researches of detecting the defects in the three bent areas are done. Through the analysis of receiving guided waves and reflection coefficients, the axial and circumferential positons of defects and the relationship of L (0,2) reflection coefficients and the extent of defects in different parts are acquired. The ability of L(0,2) across the bend to detect defects is further studied. It’s results show that L(0,2) is not suitable for detecting defects across the bend.Finally, to the problem of defects circumferential location, the circumferential reflection coefficients are got based on blind deconvolution algorithm using the simulation datas in pipe. In a word, through the numerical simulation, this paper achieved the L (0,2) reflection characteristics from the defects in different parts of straight and bent90°pipe, which provides an important defects reflection characteristics in the actual engineering detecting application.