Local Buckling Of Non-conhesive Flexible Pipe Metal Layer

The submarine pipeline,as an important component of the marine engineering transportation system,is the "Ocean Oil Lifeline." As one of the submarine pipelines,the non-bonded flexible pipe is widely used in the marine engineering field because of its good characteristics(such as its own low weight,low installation cost,strong structural compliance)in the harsh marine environment.The non-bonded flexible pipe has a multi-layered structure,and the pipe wall is a kind of composite material.The interlayer friction and interlayer contact in the pipe lead to the emergence of nonlinear problems,which increases the difficulty of analyzing the flexible pipe structure.In deep-water conditions,the force applied to the non-bonded flexible pipe mainly includes the axial compression load and the deep-water pressure load.Under this effect,the buckling failure of the non-bonded flexible tube occurs,resulting in lateral buckling and radial buckling,leading to pipeline failure,resulting in huge engineering losses.Therefore,this paper mainly studies the buckling failure of non-bonded flexible from the two aspects of radial buckling and lateral buckling.Specifically include:(1)By analyzing the effect of non-bonded flexible pipe under the action of external pressure load and axial pressure load,combined with the Vaz theory,a mechanical model of the non-bonded flexible pipe metal layup buckling analysis was created.(2)Using the non-bonded flexible pipe metal buckling analysis of the mechanical model,based on the nonlinear finite element method,using nonlinear finite element software ABAQUS established a non-bonded flexible pipe metal layer buckling finite element model calculation.(3)The factors that affect the buckling calculation results,such as the grid density and the length of the slip displacement when dividing the cells,are analyzed.The relationship between the buckling factors and the critical load of the non-bonded flexible pipe is obtained.In addition,the effect of two different equivalent beams on the stiffness of the equivalent model was also analyzed.Finally,a single spiral steel cable was used to simulate the entire metal lay,which maximized the accuracy of the calculation results.