Numerical Investigation of Bundled Subsea Power Cables Bending Stiffness

Abstract The present work evaluates the bending hysteresis of bundled subsea power cables in a triangular shape arrangement. A high-fidelity Finite Element Analysis (FEA) model is developed with ANSYS Mechanical using local analysis techniques to derive the bending hysteresis of the bundle for a typical pair of High Voltage Direct Current (HVDC) and Metallic Return (MR) cables. Two different approaches are evaluated. Initially, typical polypropylene yarns (PPY) are applied helically along the bundle. A range of tensions are examined, more precisely 50 N, 100 N and 200 N. Then, an alternative solution with polyethylene terephthalate (PET) straps placed along the bundle is examined. Different spacings of 0.5 m, 0.75 m and 1.0 m are considered. The derived bending hysteresis shows that the bending moment corresponding to the transition from stick to slip region mainly depends on the cables’ specifications and the friction coefficient. The applied tensions or the spacing affects the slope of the slip region. In addition, the equivalent bending hysteresis of each case is used to perform a typical analysis considering free laying and simultaneous lay and burial (SLB) installations in comparison with the present industry practice. The results are compared with the simplified method which is the most common practice in the industry.