Evaluation of Static Damaged Rope Response Based on Cable-Beam Element Formulation

In this paper a numerical model to evaluate the static response of damaged ropes is presented. In this study, damage corresponds to the complete rupture of one or more rope components in a particular rope cross-section. In particular, the proposed model couples the effects of two phenomena that rule damaged rope response: strain localization and asymmetry in damage distribution. The proposed model relies on the finite element method in which the damaged rope is discretized along its length into 1D two-noded nonlinear cable-beam elements with six degrees of freedom (dof) per node and Bernoulli´s kinematic hypothesis. These elements account for the helical structure of a rope (cable) as well as the axial-bending, axial-torsional, and bending-torsional interactions. Experimental static tensile test data reported in the literature of homogeneous ropes with nonlinear constitutive laws and overall diameters that range from 6 mm to 147 mm are used to validate the proposed model. Tested ropes are damaged at ropes midspan location with damage levels (percentage of the broken components of the damaged cross-section with respect to the intact rope) symmetrically and asymmetrically distributed on rope cross-sections that vary from 5% to 55%. Comparison results indicate that the proposed model accurate predicts the static response of damaged ropes, considering a wide range of rope diameter and damage level values, achieving numerical robustness and computational efficiency.