An experimental investigation on the bedding-in behavior of synthetic fiber ropes

Abstract

The bedding-in process of synthetic fiber ropes such as polyester, nylon, aramid and HMPE is of vital importance to experimental research and engineering application. In the present work, several important topics are systematically investigated by utilizing an experimental setup for cyclic loading tests of synthetic fiber ropes. These topics include the effects of bedding-in level on rope properties, a quantitative method for determining the bedding-in level of ropes and the main factors of influencing the bedding-in level. First, effects of the bedding-in level on properties of synthetic fiber ropes are investigated. A quantitative method for determining the bedding-in level is first proposed by utilizing the tension-strain curve of static tensile tests for synthetic fiber ropes based on the concept of bedding-in. This method is conducive to accurate comparison and evaluation of the elongation data obtained from different guidelines for synthetic fiber mooring ropes. Second, effects of the mean load, loading amplitude and loading cycles on the bedding-in level of HMPE and polyester ropes are systematically investigated. Based on measured data, the recommended method for determining the bedding-in procedure is proposed for synthetic fiber mooring ropes. Furthermore, an empirical expression that takes into account both the mean load, loading amplitude and number of loading cycles is proposed, which is the only one that can quantitatively evaluate the bedding-in level of fiber ropes under previous cyclic loading. The present work is of great necessity and benefit to capturing the loading history behavior and failure mechanism of synthetic fiber ropes, and also to designing convenient bedding-in procedures that are required for the installation of synthetic fiber mooring ropes.