Research on the influence of interlayer friction coefficient on the axial compression buckling failure mode of unbonded flexible pipe with tensile armor layer
During the transportation,installation,and service of flexible pipes,the tensile armor layer made of flexible and slender spiral steel strips is prone to buckling failure when external loads exceed critical values.Taking into account the nonlinear effects of nonlinear materials,geometric deformation,interlayer contact,and friction,a 63.5 mm typical unbonded flexible pipe with 8 layers was modeled using ABAQUS finite element software.The mechanical properties and buckling failure modes of the unbonded flexible pipe under axial compression loads were studied under different interlayer friction coefficients of the tensile armor layer.The results show that the interlayer friction coefficient has a significant influence on the compressive stiffness and buckling failure mode of the unbonded flexible pipe.With interlayer friction coefficients of 0.1 and 0.2 as the dividing points,both compressive stiffness and buckling failure modes exhibit a"three-stage"variation pattern.The research findings can provide technical references for the structural design and buckling failure assessment of marine unbonded flexible pipes.