Characteristics of fibre-core wire rope

Abstract

The theoretical analysis of a large-diameter stranded wire rope with fibre core, using results from a previously reported orthotropic sheet model for analysing the behaviour of its constituent helical strands, is reported. The present model is (unlike previously available theories for stranded wire ropes) capable of catering for the effects of interwire friction and contact deformations.The proposed theory provides a fairly simple means of obtaining the upper (no-slip) and lower (full-slip) bounds to rope effective stiffness coefficients under axial/torsional coupling with encouraging correlations found between the theoretical predictions for the axial stiffness under full-slip conditions and experimental data for some realistic stranded wire ropes with fibre cores.

Simple determination of the axial stiffness for largediameter independent wire rope core or fibre core wire ropes

“…It should be noted that the denominator in equation (1) is equal to the total net steel area in the wire rope's normal cross-section, with the shapes of individual round wires and spiral strands in the wire rope's normal crosssection being elliptical [9,13] and the central (king) wire in each spiral strand having a 1ˆ0 . According to equation (1), the dominant parameters controlling the rope axial stiffness are the lay angles …b j † of the strands in the wire rope and also the lay angles …a i † of the steel wires forming the individual spiral strands, with the parameter A Li also playing a role.…”

“…The exact details of the theoretical model, relating to each case of interstrand contacts in wire ropes with ®bre cores, are reported by Raoof and Kraincanic [13]. Moreover, the construction details of the wire ropes used in the present work, in conjunction with the calculation details of the Hruska's axial stiffnesses, are given elsewhere [16].…”

“…1 A typical six-stranded wire rope with: (a) an independent wire rope core (IWRC) (after Lee [8]) and (b) a ®bre core (after Velinsky [5]) predicting, with a good degree of accuracy, the mechanical characteristics of spiral strands under not just static monotonic loading (which, incidentally, is the type of loading the previously reported frictionless theoretical models have primarily been developed for) but also when the strands experience cyclic loading. The results from the orthotropic sheet concept were subsequently used by Raoof and Kraincanic [9,13] to develop two somewhat different theoretical models for analysing the various stiffness characteristics of wire ropes with either a ®bre or an independent wire rope core. As originally shown by Raoof and Hobbs [12], in repeated (cyclic) loading regimes, due to the presence of interwire friction, the effective axial stiffness of axially preloaded spiral strands (with their ends ®xed against rotation) varies (as a function of the externally applied axial load perturbations/mean axial load) between two limits.…”

“…The upper and lower bounds to the axial stiffnesses were, therefore, referred to as the no-slip and full-slip types respectively. The same terminology was also adopted by Raoof and Kraincanic [9,13] in their theoretical treatment of wire ropes, which, as experimentally demonstrated by Strzemiecki and Hobbs [10], also exhibit the limiting no-slip and full-slip axial stiffness characteristics, when experiencing cyclic axial load perturbations superimposed on a mean axial preload.…”

“…Developing simple routines, which are amenable to hand calculations using a pocket calculator, similar to those for spiral strands, as already reported by Raoof [14], is therefore highly desirable and forms the purpose of the present paper. In what follows, based on an extension of the work of Strzemiecki and Hobbs [10], in conjunction with numerical results based on Raoof and Kraincanic's models [9,13], simple formulations will be developed for estimating the no-slip and full-slip axial stiffnesses of wire ropes, with either a ®bre or an independent wire rope core, which should prove of value to busy practising engineers.…”