Investigation on damaging of ropeway hauling-ropes by twisting within operation

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Running ropes, e.g. hauling ropes of bicable jigback aerial ropeways, rotate around their axis within a ride of the system. The helix-shaped structure of a rope holds the main part of this effect, which can be separated into a non-preventable portion out of physical environmental conditions and a preventable portion due to the mechanical set-up and the combination of system-parameters. This rotation can be stored in the rope as remaining twist. Within research- and service-actions of the Institute of Mechanical Handling and Logistics of the University of Stuttgart (IFT), the results of non-destructive inspections of ropeway ropes revealed that the damage development of a hauling rope cannot be inevitably explained by obvious load-zones out of the working forces or the contact to sheaves and support towers at actual state of art. Detailed analysis of wire-break development, especially the location of wire breaks, made twisting come into focus as an accelerating parameter for rope fatigue [Briem95],[Verreet05].Up to today it has not been possible to measure and image the rotation of a rope over its total travel distance and thus to create a relation to remaining twist, respectively damage behavior. Instead only visual observation had been carried out. A new sensor, which was developed by inhouse-effort and tested successfully at the IFT, now, allows recording rotation digitally in relation to time. This reveals new, yet unknown information about the dynamic rope behavior at any section of the rope. Using these data, the twisting characteristics of hauling ropes of bicable jigback aerial ropeways can be analyzed and set in relation to relevant parameters. The aim of the project is to make the relation between rotation, remaining twist and resulting damage calculable and predictable in the practical operation of ropeways. For the first time, three fields of research will be combined to an integrated model: by continuous bending-over sheave tests with twisted lang-lay ropes, the world-wide approved Feyrer-formula will be extended to these rope constructions (field 1). Theoretical investigations on rope rotation will be developed and additionally complemented and verified by rotation measurements (field 2). Finally, measurement results of non-destructive tests will be analyzed and the residual twist will be quantified (field 3). By specifying and numbering of twist-accelerating parameters in combination with typical damages of ropes known from non-destructive tests, a new calculation method will be developed to dimension ropeway hauling ropes. This is meant to helpfully support optimization of safety, rope life time performance and availability of ropeway systems.