General Mechanical

General Mechanical

Static analysis strange results

    • javat33489
      Subscriber

      Hi all.

      I have doubts about the results of the static analysis calculation. I have a pipe that stands on the ribs. The contact bonded pipe is welded to the fins. But according to the results of the calculation, stresses were formed not at the point of contact, but where the pipe does not touch the rib. This is fine?

      Here's how it turned out:

       

      I expected stress at the point of contact between the pipe and the fin:

      I also tried MPC contact. It did not help.

      Please help me. Thanks.

    • peteroznewman
      Subscriber

      For the MPC contact, after the model has solved, in the Outline, click on the Solution Information folder. You might see the Graphics window be replaced with the Worksheet tab and it will show the text from the solve.out file.  Click on the Graphics tab at the bottom and you should see red spider elements that show how the Bonded Contact was created.  Please show that image in your reply.

      The size of the spider is controlled by the Pinball Radius in the Contact defintion.

      • javat33489
        Subscriber

        I didn't find this window. But I added Contact tracker in the results. All results are plotted like this:

        Contact:

    • peteroznewman
      Subscriber

      The largest portion of the Mechanical app where the graphics are displayed is on the Geometry tab. Look at the bottom edge of the Mechanical window. When you click on Solution Information, another tab appears called Worksheet.  Click on the Geometry tab to see the MPC spider elements.

      • javat33489
        Subscriber

        now I understand what chests are needed, here they are

         

    • peteroznewman
      Subscriber

      You can make the reach of the spider elements smaller by typing in a small distance on the Pinball Radius in the Contact definition.

      • javat33489
        Subscriber

        >>small distance on the Pinball Radius

        This does not help.

         

        1. Then I decided to check the geometry. And I saw that the details penetrate each other a little.

        2. I made two test models. One left as is with penetration. In the second, he pulled out the pipe so that there was no penetration. And assigned nodes to both on the plate in contact. In each of the models, I made one side with novdas and left the other with a full face plate contact

        3. I did the calculations and got the following results

        Model without penetration

        Model with penetration

         

        What do you think about this? I think you need to use the node method.

    • peteroznewman
      Subscriber

      You may need smaller elements on the pipe. I can't see how large they are.  I can use a Mesh Sizing for the Contact.

      • javat33489
        Subscriber

        Yes. It seems that the problem was in the pipe grid. She was rough. This is what she was like:

        I reduced the grid in contacts and this is what happened:

    • peteroznewman
      Subscriber

      Much better!

    • javat33489
      Subscriber

      Thanks a lot!

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