Pipeline Corrosion Detection And Evaluation Method Research Based On Ultrasonic Guided Wave

Pipeline transportation,as an important mode of transportation for national energy,plays a major role in national economic and social development.During the long-term service of the pipeline structure,pipeline corrosion is one of the important factors that cause pipeline failure.Therefore,it is of great social significance and economic value to study effective pipeline corrosion detection and evaluation methods,and to accurately identify and evaluate pipeline corrosion in time.In this paper,the piezoelectric ultrasonic guided wave method is used to research pipeline corrosion detection,and a pipeline corrosion model based on random media and a pipeline corrosion evaluation method based on wake energy are proposed.In the meantime,this paper used self-transmitting and self-receiving observation method combined with numerical simulation and experimental verification,which proved that this method can detect the corrosion of the pipe and the quantitative evaluation of the degree of corrosion.The main research content and research results can be summarized as the following aspects:1.This paper introduces the related knowledge of piezoelectric and discusses the related theory of ultrasonic guided waves.Based on the theoretical results of previous studies,the dispersion equation of the guided wave in the hollow circular tube was deduced,the dispersion and multi-modal phenomena of the guided wave were analyzed,and the dispersion curve,stress of the guided wave and displacement distribution diagram under different modes were drawn.According to the theoretical results,it is determined that the L(0,2)modal guided wave is used for corrosion detection of the pipeline,and a sinusoidal signal with a modulation period of 10 cycles at 140 k Hz is used as the excitation signal.2.This paper derives the finite difference discrete formula of the wave equation,discusses the relevant theory and modeling method of random media,according to the characteristics of pipeline corrosion,we propose and establish a pipeline corrosion model based on random media,simulating different length and deep corrosion pipeline model,and analyze the received waveform and sound field snapshot under different models.The simulation results show that there is an obvious scattering effect in the corrosion area,which can receive obvious defect echoes.With the depth and length of the corrosion defects increase,the amplitude and duration of the defect echoes increase.3.This paper introduces the classification of corrosion and its geometric model.Based on the geometric model of pitting corrosion,the corrosion defects of different depths and lengths are processed on healthy pipelines,and an experimental platform for pipeline corrosion detection is built.We Innovatively proposed a self-transmitting and self-receiving detection method based on piezoelectric ultrasonic guided waves,and tested the pipeline under various working conditions.The experimental results show that the obvious 5-cycle end-face reflection echo can be seen in the waveform of the noncorrosive pipeline,and there is no defect echo signal before the end-face reflection echo;the obvious flaw echo and mode conversion can be seen in the corroded pipeline waveform,and the change pattern of the wave shape with corrosion defects is similar to the simulation results.4.According to the characteristics of defect echo,we proposed an evaluating pipeline corrosion method based on coda energy,separately processed the simulated and experimental waveforms,and obtained the normalized curve about the time distribution of coda energy and the change of coda energy with corrosion conditions.The method can be used to quantitatively evaluate the corrosion depth and length of the pipeline.In summary,this paper proposes a pipeline corrosion detection method based on selftransmitting and self-receiving ultrasonic guided waves,and uses an evaluation algorithm based on coda energy to quantitatively evaluate the scope and extent of pipeline corrosion.The numerical simulation and experimental results show that,compared with the traditional ultrasonic guided wave detection method,this method has the advantages of simple observation system,small calculation amount of evaluation algorithm,and high linearity,and has a good effect for evaluating non-uniform corrosion under natural conditions.The research results have a direct effect on the health monitoring of pipeline structures based on ultrasonic guided waves.The proposed self-transmitting and selfreceiving ultrasonic guided wave observation method and pipeline corrosion evaluation algorithm based on coda energy can be used for health monitoring of other engineering structures,which has certain theoretical significance and important engineering value.