Research On Pipeline Defect Detection System Based On Multimode Ultrasonic Guided Wave

Pipeline not only plays an important role in transportation,but also plays an important role in daily life.However,due to the mechanical design,chemical corrosion,aging caused by pipeline leakage,resulting in huge economic losses and casualties.Therefore,pipeline safety monitoring should be strengthened to prevent the occurrence of safety accidents.The traditional detection method is not only time-consuming and low efficiency,but in recent years,the new ultrasonic guided wave technology has the characteristics of long distance detection and high detection efficiency.The principle of ultrasonic guided wave detection technology is that one end of the pipeline excites the ultrasonic guided wave,the guided wave is reflected in the pipeline through the defect and the end surface,and the echo is received at the receiving end.In this thesis,the finite element simulation is carried out to study the interaction between the multi mode ultrasonic guided waves and the boundary of the pipeline defects.Firstly,the research status of ultrasonic guided waves at home and abroad is analyzed,and the results of ultrasonic guided wave detection are summarized.At the same time,the concept and characteristics of ultrasonic guided wave are introduced.Secondly,build in finite element software ANSYS simulation platform,introduces the process of finite element simulation,select the relevant parameters on the modeling(unit selection,defect modeling,meshing etc.)are analyzed,and the simulation platform was verified by defect free pipe.Then,the interaction process between the multimodal and the characteristic boundary is discussed in detail.Based on the investigation of the interaction between L(0,2)and T(0,1)mode guided waves and the boundary of different thickness and different circumferential angles,the propagation law of different modes of guided waves in the pipeline is investigated.And the reflection coefficient,influence of ultrasonic guided wave detection efficiency of the normalized energy and axial error are analyzed,which determine the L(0,2)mode and T(0,1)mode of the pipe circumferential direction and depth sensitivity and energy characteristics.Then,the size of the pipeline defects is quantitatively studied by the front and rear boundaries of the pipeline defects.Finally,the simulation experiments are carried out to verify the simulation results,and the simulation results and experimental results are given to verify the validity of the finite element simulation method.