The paper reviews the recent theoretical work of the present authors as regards the prediction of the 2x2 stiffness matrix describing axial/torsional coupling of large diameter wire ropes. The theoretical analysis is based on results from a previously reported orthotropic sheet model which enables one to obtain estimates of the coefficients in the 2x2 stiffness matrix describing the axial/torsional coupling of the constituent spiral strands. The proposed model can (unlike previously available theories for wire ropes) cater for the presence of interwire friction and the various wire rope stiffness coefficients corresponding to both no-slip and full-slip regimes can be calculated. The no-slip regime corresponds to cases when an axially preloaded wire rope experiences cyclic variations of external load which are small enough not to induce initiation of gross interwire slippage within the constituent spiral strands. Theoretical models have been developed for two types of wire ropes, i.e. those with an independent wire rope core (IWRC) or the types with a fibre core: the salient features for both approaches are reviewed with an emphasis on the characteristics of various wire rope constructions. In addition, experimental results from other sources are found to provide encouraging support for the theoretical predictions in a number of areas.
In recent years there has been considerable interest in the mechanical characteristics of stranded ropes (and spiral strands). A spiral strand is an assembly of several layers of helically-laid wires with a common axis. The term rope, on the other hand, is applied to an assembly of a number of helical (spiral) strands in one or more layers over a central core. Ropes are supplied either with fibre or with steel cores, the choice being largely dependent on the use for which the rope is intended.