EFFECTS OF INTERNAL FRICTION AND TORQUE STIFFNESS ON THE GLOBAL BEHAVIOUR OF FLEXIBLE RISERS AND UMBILICALS

Flexible risers and umbilicals in offshore petroleum production systems are designed to allow large motions of the floating support vessels. In some types of operations the support vessel is moved to different positions, depending on the operation to be carried out. Such movement may induce combined bending and torsional deformation of the flexible connection lines. In configurations with reversing curvature, such as the steep wave configuration, this will lead to an interaction of bending and torque where the internal friction or other non-elastic behaviour plays an important role. In the unbonded flexible pipe structures flexural deformation induces sliding between the layers, and consequently the bending is associated with an energy dissipation. The phenomenon affects both the static and the dynamic behaviour of the flexible pipes. The present paper discusses the modelling of internal friction and demonstrates by FEM calculations how the internal friction affects the global behaviour when the surface vessel is moving. Further, the effects of boundary conditions, in particular clamping angles and swivel support, are discussed. It is shown how these boundary conditions, together with internal friction and torsional stiffness affect the bending - torque relationship.

• Supplemental Notes:
  • OMAE 1991, 10th Intl Conf on Offshore Mechanics & Arctic Engng; 23-28 June 1991; Stavanger, Norway. Sponsored by ASME et al. Procs. Publ by ASME, Vol 1, Part B, p 489 [8 p, 3 ref, 9 fig]
• Authors:
  • Fylling, I
  • Bech, A
• Publication Date: 1991

Language

• English

Subject/Index Terms

• TRT Terms: Friction; Stiffness; Torque
• Old TRIS Terms: Risers
• Subject Areas: Marine Transportation; Materials;

Filing Info

• Accession Number: 00702444
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM