Bending Moment in ANSYS AQWA

Discussion in 'Hydrodynamics and Aerodynamics' started by Mohsen, Jan 10, 2020.

  1. Mohsen
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    Mohsen New Member

    anyone has any idea to calculate Bending moment or Curvature of Mooring Cable in ANSYS AQWA?
    There is Just Cable Force ( Tension)
     
  2. Mohsen
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    Mohsen New Member

    Any Ideas? Up...
     
  3. TANSL
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    TANSL Senior Member

    Sorry if you think I simplify the subject too much. I suppose it will be calculated in the same way as in any other beam, considering the catenary as a beam subjected to pure bending: bending moment at one point of a beam will be equal to the sum of the products of the forces located to the right of that point multiplied by the distance of each force to the point under study.
    Without more data, a more concrete answer cannot be given.
     
    Last edited: Jan 11, 2020
  4. Mohsen
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    Mohsen New Member

    Thanks for your kind response.
    I want to model Electrical Cable connected the floating body. then I want to calculate fatigue damage of the cable. for calculating the FD from Result ( Solution Section ) there is just two output: A, Cable Force and B, Whole Section Force. Until here is fine, I can calculate Axial Damage by using Tension Force of the Cable. but for calculating fatigue damage I need more than Axial Damage. I need Bending Moment also
    Bending moment or Curvature needed for completing the task.
    about the modeling: Cable is modeled in Free Hanging configuration.
    please let me know if you need more information.
     
    Last edited: Jan 11, 2020
  5. Ad Hoc
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    Ad Hoc Naval Architect

    That is the usual procedure, establishing the tension in the mooring system. In general you only need to consider tension, no bending.

    It has been shown by many authors that bending and torsional effects can be neglected and that bending and torsional elasticity is of negligible importance to the mooring line tension responses, regardless of load case.
    For further reading on this subject:-

    Hall, M.; Goupee, A. Validation of a lumped-mass mooring line model with DeepCwind semisubmersible
    model test data. Ocean Eng. 2015, 104, 590–603.

    Hall, M.; Buckham, B.; Crawford, C. Evaluating the importance of mooring line model fidelity in floating
    offshore wind turbine simulations. Wind Energy 2014, 17, 1835–1853.

    Why are you saying you need more than axial damage for FD?
     
  6. Pan
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    Pan Junior Member

    Dear Mohsen,

    I am also simulating electrical cables and have the exact same problem. I don't know why these people say bending is not important. It is critical in deciding the fatigue of a dynamic submarine power cable. And we need the bending results except for tension, but I can't find bending in AQWA either. Anybody has any idea?

    Besides, how can we extract the displacement of the cable? I know we can extract the displacement of the floating structure easily, but I can't find the option for the cable.
     

  7. Mohsen
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    Mohsen New Member

    Dear Pan,
    Thanks for Reply.
    by my research, inside ANSYS AQWA there is no possibility to consider Bending Stiffness for any type of Cable (electric, Mooring, etc.). (actually you can consider, but there is no output for bending moment)
    but using AQWA GS (supervisor) there is possibility to calculate nodes displacement of the cable and using displacement of the nodes you can calculate bending damage.
    if you want we can share some information about this. be in touch by my mail @ mohsen.sobhaniasl@uniroma1.it
     
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