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Modelling a joint in a threaded rod, joint, nut and washer assembly

  1. Sep 6, 2014 #1
    I am trying to use computer modelling to see stress. I want to compare it to my hand calculation, which uses the frusta cone method to find the stiffness of the joint. This way, I can check my calculation in a conceptual way.

    The model includes a nylon insert nut, a threaded rod, a washer and a joint (some people refer to the joint as a member).
    I wanted to model these parts as solid for realism.
    The member is made of three plates. Only the plate furthest from the washer is threaded.

    The results that I get using ANSYS 14.5 are garbage and I cannot understand why (see the attachments for the model, boundary conditions and results). All contacts are set to 'bonded'. There should be a cone of stress, less at the top member, more to the middle, less at the bottom member. Please help.

    Here is the model (630 kB):
    https://www.dropbox.com/s/50od9jnfx507s8u/model.zip?dl=0
    or use:
    http://www.filedropper.com/model_3 [Broken]

    Will a threaded rod / washer / nylon insert nut / threaded member actually produce a clamping force? Its hard to picture that in my mind.

    Does the following equation apply to this situation:

    F = 0.75 * Sp

    Where F is the preload tension, resulting from the nut being tightened on the threaded rod.
    Where Sp is the proof strength of the stud.

    T = KDF

    Where T is the Torque required to produce the force that clamps the assembly together
    Where K is the nut factor
    Where F is defined as before.

    Thanks.
     

    Attached Files:

    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Sep 10, 2014 #2
    I'm sorry you are not finding help at the moment. Is there any additional information you can share with us?
     
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