Damage And Failure Of Composite Riser And Simulation Analysis Of Influencing Factors

With the development of offshore oil and gas industry in China,offshore oil and gas resources have been discovered and exploited continuously.As a channel connecting offshore oil and gas resources and offshore exploitation platform,offshore riser research has been carried out continuously in recent years.Composite riser has obvious advantages of light weight,high strength.Therefore,the research on composite riser is of great significance to the exploitation of offshore oil and gas resources in China.In this paper,based on the Hashin failure criterion and ABAQUS finite element software,the simulation mechanical experiment of composite riser is carried out.Firstly,under the action of axial tensile load and axial compression load,the damage process and failure mode of composite layer of riser are analyzed.Then,the influence of different laying order on the damage and failure of each layer in the composite layer is explored,and the best laying order is given.Finally,based on the XFEM module,the composite riser with initial crack in the metal liner is simulated,and the influence of different positions of the initial crack on the damage and failure of the riser is explored,and an optimization method to delay the damage and failure of the riser is given.In this paper,it is found that under the axial tension and compression loads,the axial layer is damaged first,and the failure modes are fiber tension failure and fiber compression failure respectively,and the rest 3 When the layer is laid as the first layer,the axial tensile stiffness of the laminated pipe can be improved to a certain extent;the angle layer should be placed between the axial layer and the circumferential layer,which can delay the occurrence of the overall failure of the laminated pipe.The best laying sequence of laminated pipe is(0~0,53.5~0,-53.5~0,90~0).Under the internal pressure,the stress and displacement results of each layer of the cracked riser are higher than that of the flawless riser;the damage time of the composite layer of the flawless riser is about 5 times of that of the cracked riser;the initial crack in the middle area of the inner liner is larger than that in the two ends.Under the action of internal pressure,adding a 90 degree composite layer between the metal inner liner and the composite layer can effectively delay the damage rate of the composite layer caused by the axial linear crack growth.