Time domain analysis of flexible risers considering non-linear bending stiffness

To investigate the dynamic time domain analysis of flexible risers due to the non-linear relationship of the bending moment and curvature of flexible pipes, the analysis model of flexible risers is established based on the lumped mass method. Non-linear bending stiffness is considered during the dynamic analysis of tension and curvature of the riser. A case study of a flexible riser at a depth of 1 500 meters in the South China Sea is presented. The results show that the tension load decreases with the increase in length, the maximum value occurs at the top point. The top and bottom points of the curvature have a larger value; the center length has the smaller curvature. When comparing the linear bending stiffness, the tension results are almost the same, but the curvatures are obviously different when considering the non-linear bending stiffness. More accurate time domain analysis results of the flexible risers can be gained by considering the nonlinear bending stiffness input.