The Calculation of Stress Distribution of Big Rope Sheaves

Thomas Kuczera

Thursday 25th September 2014

The aim of this paper is to analyse the load conditions (pressure between rope and sheave) and the stress distribution of large sheave systems. Both an analytical model for calculation of contact forces between rope and sheave was developed as well as extensive theoretical and experimental tests were realized to determine the load and stress situation of big sheaves. A practical numerical model based on a parameter assisted multi-body simulation model for the simulation of the dynamic run of a rope over a sheave was developed. The outcomes of this are the following findings. By small wrap angles (smaller than 60°) the peaks of the line contact pressure go partially or completely together when the rope enters onto and runs of the sheave and this results in a noticeable higher contact force, which was unknown so far. Within the analysed rope constructions there are maximum forces of 6 times of the constant (so far considered for the dimensioning of sheaves) part of the line contact pressure by small wrap angles. Also the rope forces and pressure load acting on sheaves due to acceleration forces during start-up process or rundown of conveyor systems, and the pressure due to a fleet angle between rope and sheave, were looked at with this multi-body-system. Finally, in the research study a method for the calculation of the load of sheaves was developed based on the finite-element-method for the calculation of the deformations and stresses of the sheave. The verification of the developed calculation and simulation methods could be done successfully by a sheave of a rope way used in practice. Consequently, the results of this research study provide fundamental guidelines for the design of big sheaves in lifting applications.

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