Research On Damage Identification Technology Of Pipeline Structure Based On Ultrasonic Guided Waves

With the rapid development of the national economy,engineering projects are becoming larger and more and more complex.,If there is minor damage,it may lead to the occurrence of major engineering accidents,causing incalculable serious impact on individuals and even the society Therefore,it is imperative to monitor the structural damage of the engineering structure.Traditional non-destructive testing methods are generally applied to a small number of devices or specific structures,but their performance is not ideal in large structures and complex device layouts.In view of the above problems,this paper adopts the non-destructive testing technology based on ultrasonic guided waves to apply to structural health monitoring.In actual engineering applications,pipeline structures are widely used in transportation fields such as oil and natural gas.Therefore,this article takes engineering pipeline structures as the research object to carry out research.The paper analyzes the propagation characteristics of ultrasonic guided waves and the characteristics of hollow cylinders,and derives the dispersion equation of hollow cylinders.The method of finite element modeling is introduced,and the engineering steps are explained,including analysis steps,grid size,piezoelectric simulation and damage modeling.Follow-up continue to study the signal processing and damage location methods.According to the study of the dispersion equation of the typical straight pipe structure,considering the influence of radial and axial displacement,it is proposed to use the L(0,2)Through the study of single damage of the tube structure,it is found that the reflection coefficient of damage increases linearly with the increase of circumferential damage size and damage depth.Smaller depths will be difficult to identify;slight changes in axial damage have little effect on the reflection coefficient.Research on double-damaged pipelines shows that when the distance between the two damages is close,the damage signals will overlap,and the damage will become difficult to identify;the near damage size will increase,the reflection coefficient will increase,and the far damage will be affected by the near damage size And the amplitude decreases.For the bending pipe,the bending radius of the bending pipe and the influence of the excitation frequency on the transmission coefficient,the influence of the excitation period on the signal amplitude,the influence of the bending angle on the characteristics of the bending pipe when the bending radius is the same,and the 90° typical bending pipe model are analyzed.The results show that the center frequency and period of the signal and the bending radius of the elbow will affect the transmission coefficient.In the case of a 90° typical bend,the L(0,2)mode guided wave will undergo modal conversion through the elbow.The transmission coefficient and modal conversion of the bend are affected by the bending angle.When the guided wave passes through the outer side of the elbow,energy accumulation occurs,and the damage is easier to detect,while the inner side has signal weakening,and small damage is prone to missed detection.In response to the needs of the experimental system for portability and intelligence,the software and hardware of the system were selected,designed and integrated.The hardware part of the experimental system is divided into four modules: real-time damage monitoring and imaging,active excitation,signal acquisition,and heat dissipation and power supply.The software part is designed for the hardware module to realize the upper computer display,signal processing and damage imaging.A damage imaging method based on regional excitation is proposed for pipe structure damage monitoring,and the effectiveness of the system is verified by experiments.