Investigation of the Damage-Dependent Response of Mooring Ropes

Abstract

The focus of this paper is on the development of an analytical damage model for predicting the deterioration of the mechanical properties of polyester (PET) ropes subjected to static tension loading. Experimental data on small PET ropes are used to estimate the evolution of damage using the effective stress concept and the principle of strain equivalence. The proposed damage model relies on an empirically based cumulative scalar damage function, which is founded on the assumption that the strain range experienced by rope elements is the main source of damage under static tension loading conditions. In this particular study, the evolution of the damage function is represented by both power law and polynomial forms. Based on experimental observations, softening behavior is developed by rope elements after reaching their maximum load-carrying capacities. This softening behavior is captured by the damage function through an asymptotic expansion technique (perturbation method). Comparisons between predicted rope responses and experimental data are provided to illustrate the use of the proposed damage model to estimate PET rope response.