Damage Tolerance of Synthetic-Fiber Mooring Rope: Small-Scale Experiments and Analytical Evaluation of Damaged Subropes and Elements

摘要

Synthetic-fiber mooring rope is being considered as an important emerging technology for economical petroleum exploration and production from offshore deepwater reservoirs. Polyester mooring ropes have been used successfully for years in Brazil and were recently approved by MMS for use in several MODU drilling operations in the Gulf of Mexico. A critical issue associated with the use of synthetic fiber mooring rope is its damage tolerance of the rope. To address this issue, MMS has initiated several research projects, including the study reported here, to better understand the effect of damage on rope strength and stiffness. In this report, comprehensive small-scale experimental study is presented on both polyester rope elements and subropes containing various degrees of damage in the form of cut yarns or elements. Two types of representative polyester ropes have been investigated in the study. The effects of damage on structural stiffness and mechanical strength of the rope elements and subropes have been determined quantitatively. Based on the established rope mechanics theory, approximate methods of analysis have been introduced to evaluate the residual failure strength of damaged and undamaged rope elements and subropes. The experimental data and analytical results obtained are compared well in all cases studied.