Study On The Damage Location Of Pipe Segment Based On L(0,2) Ultrasonic Guided Wave

As one of the five major modes of transportation,the pipeline structure is widely used in the civil engineering industry.Pipes are often destroyed during the period of use due to external force damage,aging corrosion,environmental effects and other influencing factors,resulting in environmental pollution and economic losses.Therefore,it is especially important to have a pipeline damage detection.Ultrasonic guided wave detection technology relies on its fast,efficient and safe features,so it has a broad application prospect in the field of non-destructive testing of pipeline structures.In this paper,the ultrasonic guided wave detection technology is used to determine the damage location of the defects in the straight pipe section and the curved pipe section and the degree of damage(1)Based on the theory of hollow cylindrical guided wave,this paper introduces the concept of guided wave,the dispersion of guided wave and multimodal phenomenon,and draws the dispersion curve of ultrasonic guided wave of pipe structure by MATLAB software It can be seen from the dispersion curve that the L(0,2)mode ultrasonic guided wave has a large wave velocity,and substantially no dispersion occurs in a certain frequency segment,and is easily distinguished from other waveforms.Therefore,the L(0,2)modal ultrasonic guided wave is selected as the excitation mode of this paper(2)The finite element model of straight pipe section and elbow section is established in ABAQUS finite element software,and the dynamic analysis module is used to simulate the propagation of ultrasonic guided waves in the pipe section.The results show that the L(0,2)modal guided wave with excitation frequency of 70KHz and excitation period of 10 is most suitable as the excitation waveform of this study.In the finite element software simulation,the axial position of the defects in the straight pipe section and the curved pipe section can be clearly and accurately detected(3)When simulating the single pipe section and the elbow section,the degree of damage of the defect can be roughly judged by changing the circumferential angle of the damage and fitting the reflection coefficient curve.When simulating the double damage of the straight pipe section and the curved pipe section,by changing the circumferential angle of the damage farther from the excitation end,the reflection coefficient curve is also fitted to judge the damage degree.The results show that the ultrasonic guided wave is feasible for the location and damage degree of the pipe segment damage,and the propagation in the straight pipe is very close to the theory,but the propagation velocity of the ultrasonic guided wave in the curved pipe is smaller than the theoretical value.When simulating the influence of the weld on the guided wave propagation characteristics,it is found that the guided wave will partially reflect when passing through the weld,and the guided wave will propagate slightly more energy than the weldless pipe when propagating in the welded pipe.(4)The accuracy of the simulation process for damage and weld positioning was verified by designing straight pipe sections and elbow sections.At the same time,the errors generated during the test and the causes of signal interference were also analyzed.The results show that the energy loss of the ultrasonic guided wave propagation is more serious during the test,and a large amount of clutter is generated,which has certain interference to the detection results.