General Mechanical

General Mechanical

Creating stress concentrations due to boundary conditions

    • albin.linderstam
      Subscriber

      Hello,

      Is there a way to create a smooth transition for e.g. a fixed support?

      I use a fixed support for a specified cylindrical surface to mimic a number of thread.

      I splited the cylindrical surface in SpaceClaim, since only part threaded area is loaded.

      However, it seems that that the fixed support creates a stress concentration that is not realistic.

      Any suggestion how to improve the analysis to avoid this problem?

      Sure I can neglect that area, but I hope there is another way.

      Perhaps I can remove the sharp corner simply add a radius to the corner of the blue surface (fixed support area).

      Regards, Albin

    • albin.linderstam
      Subscriber
      Perhaps your solution from https://forum.ansys.com/discussion/470/simple-method-for-simulating-local-deformation-near-fastener-threads is the way to solve this?
      You also have some broken threads, e.g. found here:
      I also found a couple of other broken links that you recommended in other threads with interesting topics. I hope they can fix this :)
    • albin.linderstam
      Subscriber
      the other thread I was talking about was regarding to analyze the threads themselves.
      In the link above, you commented: "Another posthas an example of how to evaluate failure in the threads themselves.", but that link was broken unfortunately.
    • albin.linderstam
      Subscriber
      I tried to apply Contact Geometry Correction: "Bolt Thread", but I'm not sure how to selecting Starting Point and Ending Point.I can only select Global Coordinate System, and I try to select surfaces/edges in my model, but nothing happens.
      Also, regarding the Mean Pitch Diameter, should this be set to 8mm for a M8 like in your example, or to the actual mean diameter found in standards? E.g. 7.188mm (coarse) and 7.513 (fine) for a M8.
      The outer diameter of the cylinder ("bolt") and the inner diameter of the "nut" is set to 8mm.
    • peteroznewman
      Subscriber
      Why are there 4 faces on the contact? I don't know if the Bolt Thread geometry modification works on more than one face or if the face has to be a complete cylinder.
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