Research On Health Dectection Method Of Tubular Structure Based On Ultrasonic Guided Waves

Industrial pipelines often work in the external environment.The temperature difference is large,and the working conditions of pressure from different directions of the pipeline are complicated,which is prone to yield fatigue,friction loss,rust thickening,expansion deformation,and thus different degrees of corrosion.Therefore,these potential dangers must be detected as early as possible,otherwise they will cause structural damage then result in serious harm to safety,environment and economy.After years of development,ultrasonic guided wave technology has been widely used in the field of structural health detection.However,due to multi-modes and dispersion characteristics of the guided wave,the detection signals are complicated and difficult to distinguish,especially in the detection of small defects.The difficulty of defect identification will be further increased,which present new challenges for researchers.In addition,since the pipeline is often affected by external forces and other factors during the use of the pipeline,minor cracks are generated inside the pipeline,and the traditional detection method cannot be accurately and timely judged.Therefore,long-term monitoring experiments are important steps to corrosion changes in structural health testing methods.In this paper,the ultrasonic detection technology is used to study the defect detection and identification methods of straight pipe and elbow.Main research contents are as follows: Based on the basic propagation characteristics of ultrasonic guided waves in pipelines,different ultrasonic guided wave modes are selected according to different research objectives;the pipe model with defects is established to provide sufficient signals for the analysis of the subsequent defect imaging algorithm;The experimental study on corrosion defects detection of curved pipelines is carried out.By comparing and analyzing the detection signals,the correspondence between corrosion defects of varying degrees and detection signal characteristics is established.Through experimental research,the variation of defect detection signals with different temperature conditions is analyzed.Based on the array detection of guided waves,an defect imaging algorithm based on time-reversal operator decomposition is studied and verified by numerical simulation.