Novel Simulations of Subsea Cables and Umbilicals with Bitumen-Coated Armor Wires using UFLEX2D.

Bitumen is field-proved to be a highly effective corrosion protection for steel armor wires in subsea power cables, umbilicals, and power umbilicals. Bitumen's viscoelastic properties are known to influence the mechanical properties of cables, umbilicals, and power umbilicals. Still, common industry practice is to neglect bitumen and instead assume dry friction, also at bitumen-coated contact surfaces. This paper presents novel simulations of an umbilical with bitumen-coated armor wires using the cable and umbilical simulation software UFLEX2D. To the author's knowledge such simulations have not been published in the scientific literature before. The UFLEX2D simulations show that the bending stiffness is highly sensitive to bitumen's temperature and to some extent sensitive to the umbilical oscillation frequency. The paper also compares bitumen with dry friction. The simulations reveal that bitumen introduces a phase shift between the umbilical's bending curvature and bending moment. This paper therefore introduces the complex bending stiffness which also includes this phase shift. [ABSTRACT FROM AUTHOR]