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Fatigue prediction for strands and wire ropes in tension and bent over sheave wheel

  • Author / Creator
    Wokem, Christian O.
  • Strands and wire ropes are widely used in many civil and mining engineering applications, such as encountered in cable stays for bridges, suspension bridge elements, mooring structures, cranes, ropes for shovels, draglines, and for elevators and mine shaft cages and skips. These ropes are broadly classified as stationary and running ropes depending on whether they are subjected to predominantly tensile loads or both tension and bending, over a sheave. The primary reason for failure in such strands and wire ropes subjected solely to tension are fretting fatigue scenarios, manifest as individual wires rubbing against each other as a load is cyclically applied. For strands and wire ropes also bent over sheaves, the failure is invariably identified at the top of the sheave where the rope comes into maximum contact with the sheave. To this date, research based prediction of fretting induced fatigue life reduction of strands and wire rope has partially but not wholly been investigated. Feyrer (2007) performed milestone direction work in proposing regression models, established through regression coefficients, that could be used to calculate the anticipated fatigue life of strands and wire ropes for tension only, and tension plus bending over sheave specific configuration cases. The collection of regression coefficients established by Feyrer were limited to the cases he proposed, such that the current research here extends that knowledge base, through investigating the effect of sheave to rope diameter ratio, , applied load, , sheave contact length of rope, , and sheave groove radius, . These results were analyzed in a parametric study generating regression coefficients to permit additional strands and wire rope types not included in Feyrer`s original investigation. Specifically 7, 19, 91 and 92-wire strands in tension, independent wire rope core (IWRC) and 6 19 Seale-IWRC wire rope (usually called 6 19 Seale wire rope) in tension were analyzed, and subsequently their predicted cyclic tension fatigue life is obtained using a stress based approach. The behaviour of 7 and 19-wire ropes subjected to both tension and bending over sheaves fatigue were also investigated. In all cases investigated, S-N fatigue regression models were proposed. Since the stress based method used for fatigue life prediction is dependent on a stress concentration factor or stress correction factor, both prediction routes have been compared with subsequent recommendations for practical application. Finite element analysis of the strand or wire rope models yielded the stress concentration and correction factors necessary for the fatigue life prediction.

  • Subjects / Keywords
  • Graduation date
    2015-06
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/R36T0H32H
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
    English
  • Institution
    University of Alberta
  • Degree level
    Doctoral
  • Department
    • Department of Civil and Environmental Engineering
  • Specialization
    • Structural Engineering
  • Supervisor / co-supervisor and their department(s)
    • Samer, Adeeb (Civil and Environmental Engineering)
    • Gilbert, Grondin
    • Tim, Joseph (Civil and Environmental Engineering)
  • Examining committee members and their departments
    • Roger, Hobbs (Civil and Environmental Engineering)
    • Szymanski, Jozef (Civil and Environmental Engineering)
    • John, Nychka (Chemical and Materials Engineering)