FINITE ELEMENT SIMULATION OF A STEEL WIRE ROPE HANGING FROM A SHEAVE, CALCULATION OF THE STRESS HISTORY IN THE WIRES

Summary

During offshore installation operations, heavy loads are regularly suspended below the crane top sheave while awaiting completion of supplementary tasks onboard or subsea. Although the rope is not payed-out, at the sheave exit point it is subjected to movement from vessel motions. This is damaging for the rope, as it produces very large stress variation in the wires at the contact points between the rope and the sheave. This stress variation is however not known and empirical rules are applied by the installation contractor. A better knowledge of this stress history can help define more physically based installation limits. A numerical model for multi-stranded steel wire rope that individualizes the loading of each strand, including the friction forces between the strands, while simulating several meters of rope was developed. This model was utilized to simulate the rope hanging from a sheave and to calculate mean and alternate stresses for each wire.

Author(s): M. Martinez, R. Babu Kante, D. Cannell and P Sicsic