Simplified analysis of the influence of strain localization and asymmetric damage distribution on static damaged polyester rope behavior

In this paper, two factors that govern the response of damaged ropes are numerically examined independently: strain localization and asymmetric damage distribution. These two mechanisms are studied by using two nonlinear mechanical models that account for the strain localization around the failure site due to frictional effects (SLM) and the presence of unbalanced radial contact forces within a rope cross-section due to the asymmetry in damage distribution (ADDM). These models are applied to an available set of static tension tests on asymmetrically damaged, large-scale polyester ropes. The initial damage level of the rope cross-sections and rope diameters varied from 5% to 15% and from 32 mm to 166 mm, respectively. A semi-analytical proof is given to show that SLM and ADDM provide upper and lower bounds, respectively, to the damaged response of the ropes analyzed. Results indicate that, relative to the intact rope, the SLM predicted a reduction in rope capacity similar to the damage level and a maximum reduction in rope deformation capacity equal to 16% for an effective damage level equal to 25%. Conversely, the ADDM predicted a reduction in rope residual strength slightly greater than the damage level and a maximum reduction in deformation capacity equal to 3%.