Расчёт протяжки полимерного лайнера в стальной трубопровод

Abstract

Background Not all parts of extended objects such as trunk pipeline systems are available for visual check and in-line inspection. The pipeline own frequency of flexural oscillations are used for permanent monitoring of internal pressure and density of fluid. The change of moment of inertia of the cross section of the pipe could be determined according to the change of the natural frequencies of the flexural oscillations at constant pressure and density of the fluid in the pipeline. Aims and Objectives To determine the density of the fluid or axial moment of inertia of the cross section; and to determine the internal pressure of the natural frequencies of the bending oscillations of the pipeline. Methods The Kirchhoff model equation of flexural oscillations of the pipeline is used. Application of this equation, which determines the form of bending oscillations and the boundary conditions for the pipeline clamped at the edges, allows obtaining of the frequency equation, on the basis of which the direct and inverse problems are solved. Results It was found that increase of the internal fluid pressure or density within the pipeline leads to reduction of the natural frequencies of flexural oscillations and the increase of the axial moment of inertia of the cross section increases the natural frequencies of flexural oscillations of the pipeline. Two natural frequencies of the flexural oscillations could be used to determine the fluid density and the internal pressure in the pipeline or axial moment of inertia of the cross section of the pipeline. Conclusion The obtained results could be used to determine the fluid density and the internal pressure in the pipeline or axial moment of inertia of the cross section of the pipeline by two natural frequencies the flexural oscillations.