ON THE ASSESSMENT OF THE RESIDUAL SERVICE LIFE OF FIBRE ROPES IN USE

Summary

Polymeric fibres are very promising for rope technology, because of their high strength at very low density. One of the hindrances is that the understanding of their fatigue performance is limited. The prediction of fatigue behaviour using existing calculation methods is not reliable. There are thus far no clear discard criteria for fibre ropes available, because the damage mechanisms of fibre ropes have at this time not been fully discovered and no non-destructive test methods are available for recording the fatigue condition of fibre ropes.

The paper introduces the viscous deformation of polymeric fibres under long-term load, which plays an important role with respect to their deterioration and mechanical fatigue failure.

Based on theory and on experimental fatigue test results it is suggested to substitute the existing equations for the prediction of load induced fatigue failure of ropes by a strain-based concept, which accounts for the total viscous deformation in a rope with respect to a critical strain level as to be the damage criteria. It is believed that the proposed concept also fits steel wire ropes and can be employed generally to describe the loading induced damage evolution in ropes during service application.

Keywords: Polymeric fibre rope, damage mechanism, fatigue behaviour, fatigue failure prediction, strain-based concept, novel approach

Author(s): A. Frick, W. Frick and G. Novak