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THE TORSIONAL BEHAVIOUR OF TRIANGULAR STRAND
STEEL WIRE ROPES FOR DRUM WINDERS

By: Gerhard Rebel

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand,
in fulfillment of the requirements for the degree of Doctor of Philosophy.
Johannesburg, 1997

A wire rope tension-torsion testing machine has been developed for conducting tests under constant twist, load and torque conditions. The relationship between load and torque, for constant twists, is used to determine the in-service lay length distributions. 

It has been found that the lay length at which a rope is manufactured significantly affects the in-shaft boundary conditions in the lay length analysis. Correct lay length distributions values, in the suspended rope section, are a prerequisite for the rotation calculations. The rotation analysis takes into account changes in rope torsional stiffness resulting from the no-slip to slip transition, between the rope wires, associated with twist displacements. This varying torsional stiffness characteristic is a function of the rope load and state of twisting (lay length). The hysteresis response during constant load tests, constitutes a first order effect, but it has been ignored in previous attempts at calculating in-service rope rotation. Consequently, far more rotations were forecast than is actually the case. With the new model, rope lay length and rotation predictions compare favourably with actual measured behaviour in existing shafts. 

The results of in-service lay length and rope rotation measurements, conducted in shafts up to 2500 m deep, are also presented. Parameters which have the greatest influence on the torsional behaviour of triangular strand ropes in vertical shafts have been identified and recommendations are made on how the depth limit of application for these ropes may be extended.

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TORSIONAL BEHAVIOUR OF WIRE ROPES FOR KOEPE WINDERS

By: Jason Minas Yiassoumis

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand,
Johannesburg, in fulfilment of the requirements for the degree of Master of Science in
Engineering, Johannesburg, 1992.

ABSTRACT

The torsional behaviour of steel wire ropes used on Koepe winders for vertical shafts is analysed. Theoretical models have been developed for the behaviour of both the head and tail ropes after correcting an assumption made by previous researchers regarding the torque in the ropes. The theoretical models utilise experimentally obtained rope properties. The properties were measured from rope samples tested in a laboratory using specially developed equipment and software. Instruments were designed and used for in-situ measurements on an 1800 m deep shaft during a complete return trip. Some of the measurements were affected by unexpected strong torsional oscillations. However the general trends of the measured torsional behaviour were correctly predicted by the theoretical models. Discrepancies are attributed to the difficulties of obtaining true rope properties, to assumptions made in order to obtain a workable model and to inaccuracies in the measured behaviour because of the strong torsional oscillations. Further research is recommended. Nevertheless there is sufficient correlation between the models and the experiments, as well as with other published results, to draw certain conclusions with confidence. In particular the results confirm the adverse effect of hoisting depth, the need to use non-spin ropes and the need for swivels at both ends of freely looped tail ropes. New findings include the importance of balanced frictional torque between the two swivels of a tail rope and the realisation that the rope rotation is caused by the torque difference between the two legs of a head or tail rope and not the absolute value of the torques. The results also emphasize the important role of the torsional stiffness of a rope in relation to its torsional behaviour. The use of theoretical models to design or select ropes suitable for specific Koepe winders is suggested.

TORSIONAL BEHAVIOUR OF WIRE ROPES FOR KOEPE WINDERS (4706 kB)

TORSIONAL BEHAVIOUR OF WIRE ROPES FOR KOEPE WINDERS APPENDIX (1939 kB)