Effect of broken rope components distribution throughout rope cross-section on polyester rope response: Numerical approach

This paper deals with the effects of broken rope components on rope failure axial strain, failure axial load and rope stiffness using 3D finite element (FE) analyses. The analyses are focused on small-scale polyester ropes (ropes diameter equal to 6 mm) with different numbers and distributions of broken components throughout rope cross-sections. These small-scale ropes are members of bigger ropes used as deep water mooring systems. For computational purposes, ropes are subjected to extension with both ends fixed against rotation. Numerical simulations show that the reduction of the residual rope strength and the axial strain at the onset of rope failure due to the presence of broken rope components depend on the length of the rope, degree of asymmetry of the rope cross-section and on the number, location throughout rope cross-section (defines type of contact between rope components), and axial distribution of the broken components. Hypotheses associated with a 2D numerical model extended to include the length effect on damaged rope response, which accounts for strain localization around the failure region, are tested by comparisons with 3D FE models results and available experimental data obtained from static tensile tests. The results of this study should serve as a basis to develop more complete numerical models to predict damaged rope response.