Techno Press
You logged in as Techno Press

Ocean Systems Engineering
  Volume 8, Number 2, June 2018 , pages 101-118

Incorporating magneto-Rheological damper into riser tensioner system to restrict riser stroke in moderate-size semisubmersibles
Zaid Zainuddin, Moo-Hyun Kim, Heon-Yong Kang and Shankar Bhat

    In case of conventional shallow-draft semisubmersibles, unacceptably large riser stroke was the restricting factor for dry-tree-riser-semisubmersible development. Many attempts to address this issue have focused on using larger draft and size with extra heave-damping plates, which results in a huge cost increase. The objective of this paper is to investigate an alternative solution by improving riser systems through the implementation of a magneto-rheological damper (MR Damper) so that it can be used with moderate-size/draft semisubmersibles. In this regard, MR-damper riser systems and connections are numerically modeled so that they can couple with hull-mooring time-domain simulations. The simulation results show that the moderate-size semisubmersible with MR damper system can be used with conventional dry-tree pneumatic tensioners by effectively reducing stroke-distance even in the most severe (1000-yr) storm environments. Furthermore, the damping level of the MR damper can be controlled to best fit target cases by changing input electric currents. The reduction in stroke allows smaller topside deck spacing, which in turn leads to smaller deck and hull. As the penalty of reducing riser stroke by MR damper, the force on the MR-damper can significantly be increased, which requires applying optimal electric currents.
Key Words
    semisubmersible; dry-tree unit; TTR (top-tensioned riser); MR (magneto-rheological) damper; pneumatic tensioner; riser-stroke limit; active control; deepwater
Zaid Zainuddin, Moo-Hyun Kim and Heon-Yong Kang: Department of Ocean Engineering, Texas A&M University, College Station, Texas, USA
Shankar Bhat: Department of Civil, Structures and Offshore, Sabah Shell Petroleum Co. Ltd., Kuala Lumpur, Malaysia

Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2023 Techno Press
P.O. Box 33, Yuseong, Daejeon 305-600 Korea, Tel: +82-42-828-7996, Fax : +82-42-828-7997, Email: