Local Buckling Study On Subsea Pipeline With Ellipticity-denting Defect

Ellipticity and denting easily occur in the manufacturing,burying and using of subsea pipelines,defects will influence the local buckling of subsea pipelines,leading to the damage of the whole pipelines system.Therefore,it is important to study on the local buckling of subsea pipelines with ellipticity-denting defect.The paper research deeply on the most common defects of pipelines,ellipticity and denting.In another words,this paper study on the local buckling of pipelines with the ellipticity and denting.Finite element software ABAQUS is used to numerical simulate the local buckling of subsea pipelines with different ellipticity or denting.Compare the numerical simulate result with the pressure cabin experiment to verify the result of simulation.The paper's research is mainly on these aspects as follow.Develop a finite element model of subsea pipelines with ellipticity and denting defects,.Conduct pressure cabin experiment,comparing the result of experiment and finite element simulation,to verify the correctness of the finite element model.Using Python to parametric model,calculating different pipeline models.Through the numerical simulation of the subsea pipeline's local buckling under external pressure,getting the relation between collapse pressure of pipelines with denting depth,denting shape,denting width,ellipticity of pipelines,diameter-thickness ratio of pipelines,proposing Referring to criterion,Coefficient of Shape to describe elliptical and denting defects of subsea pipelines,discuss Coefficient of Shape is influenced by which variables and do the sensitivity analysis of Coefficient of Shape.Study on the local buckling of subsea pipelines with denting under indenter with dynamic loading,comparing the result of denting under indenter with dynamic loading with the result of denting under indenter with static loading.Analysis the diverge degree between these two loading ways,study on the relation between denting and the kinetic energy of indenter.Through calculation and experiment,verify the reliability and applicability of the model,put forward different method to discuss different pipelines,guiding the actual.