WEAR-BASED PARAMETER FOR CBOS FATIGUE IN FIBER ROPES

Summary

Many fiber ropes fail in CBOS fatigue primarily through progressive internal wear between and among adjacent fibers. The present study proposes a wear-based damage parameter developed using simple abrasion assumptions. Damage is modelled as the combination of pressure and relative fiber movement. Total pressure is separated into external and internal components, with additional terms for gravity and centrifugal force. The resulting damage parameter has a form similar to other suggested scaling factors such as sheave pressure (%BL/D:d), with additional terms involving D:d. The new parameter is shown to be useful in combining experimental data from different sheave sizes. A major limitation of the model is reliance on at least one arbitrary constant. The goal of further model development is to eliminate such constants, to better understand the physical mechanisms of damage progression and ultimate failure. Results suggest that relative rates of sheave pressure change and inter-strand movement during sheave entry and exit should be a topic for additional study

Author: F. Sloan