Research On Defect Detection Of Pipelines Based On Time-Reversal Guided Waves

Pipelines have been widely used in oil,chemical and other industries.However,In the process of manufacturing,installation,service and so on,various kinds of defects which will bring potential safety hazard to the pipeline transport system can be created.People's long-term concern is to find a convenient and fast way to quickly and accurately detect the using pipelines.Nowadays,the guided wave has attracted great attention,because of its advantages of fast and accuracy,wide detection range,ease of implementation and low cost.The specific works of this paper are in the following:The background and significance of pipeline guided wave testing research was analyzed in this paper,and the research situation in ultrasonic guided wave testing field was summarized,the basic concept of guided wave and theoretical knowledge was introduced,the hollow tubular ultrasonic guided wave and time reversal theory was summarized.According to the dispersion properties of guided waves in pipe,the guided wave of L(0,2)mode was selected to detect defects of pipes.The numerical simulation of guided wave testing for pipeline detection was mainly provided by finite element software ANSYS.The basic principles and specific modeling methods and processes of establishing pipeline finite element model were systematically described.The cracks at different circumferential size and different diameter were created,which were detected by the numerical simulation technology and the relationship between reflection coefficient and extent damage was also studied.The time reversal method was used to overcome the problems that the echo of defect isn't easy to identify.It is shown that the reflection amplitude of different crack can effectively be enhanced after time reverse numerical simulation,The smaller circumferential size is,The bigger the ratio of amplitude of the defect is.The time reversal method can improve significantly the capability of detecting defect.According to the displacement field features of propagating through the bent 90° pipe by L(0,2),the bended part was divided into three areas,The simulation researches of detecting the defects in the three bended areas were done,the detected waveform was used to locate the defect.At the same time,the time reversal method was used to detect the defects of bent pipes.The results show that the time reversal method is also suitable for the detection of defects of bent pipe.In addition,the double defect model was also studied,and the position of the defect was accurately obtained.The reflection coefficient was drawn.Ideas and research methods in this article have certain enlightenment to solve the problem of ultrasonic guided wave in defect detection,which can know comprehensively the situation of pipelines and increase the effectiveness of detection.The paper provides a certain theoretical foundation and project application value on guided waves inspection.