Research On Composite Pipeline Damage Based On Ultrasonic Guided Wave Technology

With the development of modern industry,pipeline transportation plays a very important role in the transportation of carrier transport,which not only brings convenience to transportation but also greatly increases economic benefits.However,because of the many problems in the process of production,assembly and service of pipelines,the harsh environment will cause serious corrosion or extrusion of pipelines.Therefore,its safety performance is particularly important.The traditional detection technology cannot quickly and quickly perform in-service pipelines.Accurate detection requires a new type of inspection technology to meet industrial needs.Non-destructive ultrasonic wave guided non-destructive testing technology itself is relatively low frequency,along the line detection,long propagation distance and other characteristics,is the first choice for pipe damage detection.In this paper,the dispersion equation of the guided wave in the composite pipeline based on the spectral method is introduced in detail.Instead of the original traditional method of searching for the root,the unknown function is used as the interpolating basis function of the Chebyshev polynomial,and the displacement,stress and strain equations are converted into the form of the differential matrix.Then,according to the interface continuous conditions and boundary conditions,the corresponding lines in the Helmholtz equations of the longitudinal and transverse wave speeds are replaced,and the linear equations are solved in differential terms.Using MATLAB numerical programming,the principle of selection of guided wave number and phase velocity for various composite pipes was analyzed,and dispersion curves,attenuation curves and displacement distribution curves were calculated respectively.By analyzing dispersion,attenuation and displacement distribution curves,the law of wave number and phase velocity with frequency can be determined to find modalities and frequencies suitable for damage detection of various composite pipelines;liquid-filled elastic pipelines are compared with hollow elastic pipelines.Due to the coupling effect of water and pipelines,unknown modalities are present and the number of modalities is also changing.Compared with viscoelastic pipelines,viscoelastic materials are attenuated due to the coupling of viscoelastic materials,and attenuation of all modes is severe.There are two types of truncated modes in the frequency range;the liquid-filled elastic pipe with the coating layer and the liquid-filled elastic pipe with double layers are more complex in the guided wave propagation characteristics,and all of them have unknown modes and exist only in the liquid-filled state.The L(0,2)mode is used to perform damage detection on pipelines and liquidfilled pipelines.ANSYS numerically simulates various defects of pipelines.In order to get closer to the actual defects,pre-processing is performed using geometric modeling and segmented grids.Reducing the error;L(0,2)modality proposes the dispersion correction factor for the damage detection of pipelines and liquid-filled pipelines,and analyzes the relationship between the reflection coefficient and defect information.Based on the control variable method,the reflection coefficient is obtained with the week.The trend of defects and radial defects is changed;the reflection coefficient under the condition of liquid filling is simulated and the reflection coefficient of the hollow pipe is measured;the principle of displacement time-curve nodes are superimposed to make the reflection information more obvious and can more effectively determine the defect position and damage degree.