Damage Imaging On Pipe Structure Based On Ultrasonic Guided Waves

Because of its safety,stability and reliability,pipe structure has been wildly used in construction,industry,municipal engineering,ships and other fields,it has become one of five major modes.During the service period,pipe structure damage may occurs due to external force,aging corrosion,environment effects and so on,which easily causes environment pollution and property loss.Therefore,how to quickly and efficiently detect the pipe structure to ensure industrial pipelines and urban pipeline networks safe and reliable,which is especially significant.Ultrasonic guided nondestructive detection technology due to its fast,efficient and safe features,has broad application prospects in the field of pipe structures nondestructive detectionIn this paper,the ultrasonic guided wave detection technology is used to identify,locate and image the single defect and double defects of the straight pipe structure.First of all,based on the theory of hollow cylindrical guided waves,introducing guided wave related concept and guided wave attenuation,deducing the guided wave dispersion equation of the pipe structure and drawing the dispersion curves,understanding the characteristics of the longitudinal mode,bending mode and torsional mode in the pipe structure,explaining the reasons why choose L(0,2)model wave to detect pipe damage,and introduce the basic principle of ultrasonic guided wave detection in the pipe section structure.Then,based on ABAQUS software,establishing the finite element model of the pipe structure,introducing the principle of element type choosing and mesh division,explaining the reasons for simplifying boundary conditions,and the explicit dynamic analysis module is used to simulate the propagation of ultrasonic guided wave in the straight pipe segment,comparing the damage identification results of pipe structure,the most sensitive signal cycles and excitation frequency for pipe segment damage identification is selected.Thirdly,through the numerical simulation,the influence of the single defect depth and the circumferential length on the L(0,2)modal guided wave reflection coefficient in the pipe segment is studied.the double defect size of the straight pipe segment,the distance between the defects and the circumferential position between the defects are studied,to study the influence of these influencing factors on the defect recognition effect,the propagation path of the ultrasonic guided wave in the pipe segment is analyzed.In addition,introducing the method and principle of board structure damage identification and positioning,and based on the elliptical positioning imaging method of the plate structure,the axial positioning method and damage imaging method that are suitable for single defect and double defect of the pipe segment are deduced.Finally,this paper introduces experimental instruments and experimental procedures,conducts ultrasonic guided wave experiments in non-destructive sections to selects appropriate excitation frequency and excitation signal period,and the effectiveness of the above method is verified by the ultrasonic guided wave flaw detection experiment of single defect pipe segment.The axial positioning and damage imaging results of the finite element model defect indicate that the three-point axial positioning method and the circular track imaging method can effectively reflect the axial positioning and circumferential length information of the single defect and double defect of the pipe structure.The results of the ultrasonic guided wave flaw detection experiment indicate that the above two methods are feasible,but the accuracy of the two methods mainly depends on the accuracy of the ultrasonic guided wave signal data.