Multi-scale coupling numerical modeling of metallic strip flexible pipe during reel-lay process

Complex plastic deformation and local buckling may occur due to the nonlinear contact between the pipe and drum in the offshore pipeline laying by reel-lay method. In this paper, material performance tests are carried out to obtain the nonlinear stress-strain constitutive models for high density polyethylene (HDPE) material and steel strip. Meanwhile, full-scale tensile tests are also conducted to acquire the tension-strain correlation of metallic strip flexible pipe (MSFP). Then, shell element and solid element are combined to establish an ABAQUS multiscale finite element model (FEM) for MSFP under the coiled laying condition. The proposed multi-scale FEM consists of three components, i.e. two simplified components and one fine component, which could accurately and efficiently simulate the mechanical properties of flexible pipe under the coiled laying condition. The results indicate that: due to the radial extrusion restriction of spiral steel strips, the Mises stress distribution of inner HDPE layer shows a more uniform spiral strip distribution than outer HDPE layer; the most dangerous condition for MSFP may be when it is just partially wound up on the drum; the effect of friction coefficient on the spiral steel strips seems obviously larger than the effects of traction force and drum diameter.