An innovative method for wire rope fatigue life evaluation

Wire ropes are frequently involved in critical applications with low safety factors, complex systems and severe environmental conditions, therefore a reliable fatigue life evaluation has assumed a fundamental importance. Fatigue life can be considered in terms of the damage that each component of the reeving brings to the wire rope, which reaches the discard criteria when the maximum allowable amount of damage has accumulated. This paper describes an innovative method which allows evaluation of the damage brought by each individual component of the reeving as a combination of its load and geometry. This method evaluates timing and mechanism of failure before formation of broken wires and the reaching of the discard criteria, therefore its utilisation during the design stage, system functioning and rope inspection in combination with NDT leads to an improvement in the rope’s reliability. Being calibrated with the results of tests performed on large diameter non rotating wire ropes, it is extensively utilized in the field of offshore cranes to assist the contractors in the design of the system and in the utilisation of the wire rope.

Author(s): L. Lombardi and F. Clerici