Computer modelling of large, high-performance fiber rope properties

Rope development has historically involved building a prototype rope, testing it to determine performance, and then building another rope in an attempt to improve that performance. This empirical method was affordable with small conventional ropes. Interest is now focused on developing very large ropes made of polyester and high modulus materials such as aramid. For such ropes, the empirical method is too expensive and too time consuming. The use of rope computer models can greatly reduce rope development costs. Parameters such as fiber properties and component arrangements can be studied to determine a near-optimum design before making and testing a prototype rope. Test results can be used to calibrate the computer model, and additional modelling can then be conducted to improve rope properties or predict rope performance under other conditions. This paper presents several examples. A study predicted how a slight change in strand lay length can significantly improve rope cyclic load fatigue life. Modelling of hysteresis heating helped plan a laboratory test program and complemented the testing by extrapolating the measured results to larger ropes and other test conditions.