1 Reply Latest reply on Jul 31, 2013 11:32 AM by Jared Conway

    Curvature Based Mesh does not click well with non pentration contact set?

    kk cheng

      Hi

      I am a self learner in Simulation, have been trying out ways I could use simulation to anticipate how objects are bent, stressed.

      I used curvature based mesh quite oftenly because it can solve faster with more elements compared to standard based mesh.

       

      However I just could not get curvature based mesh to work with a contact set of non penetration. But once I switch to standard based mesh, eveything seems working.

      I need to ask fellow users of Simulation, is this a bug or something I have not done correctly?

       

      I am using SW2010 Simulation

       

      Note that the 3 buttons are not bonded to the upper flat bar, it has very small gap. I used contact set non penetration between the surface of each button and the face of the flat bar facing down.

       

      Capture.JPGCapture2.JPG

       

      Then my fellow engineer told me if I were to make curvature mesh works with non- penetration, I got to reduce the surface of the contact set of the flat bar by creating split lines. So I did a 3 circular splitsfor each button on the flat bar. To my surprise it worked!!

       

      So my next question is, why it worked and how do I define small area? Is there other way I could have make it work with non-penetration contact set?

       

      Untitled.jpg

       

      I would be delighted to hear any kind advice.

       

      Thank you

        • Re: Curvature Based Mesh does not click well with non pentration contact set?
          Jared Conway

          could it be a bug? possibly. 2010 was the first year of the curvature based mesh and that was 3 versions ago. are you guys on subscription? might be worth upgrading for solving this problem and all the new features that have been added. consider posting your model to have someone check it in a later version. or work with your reseller on that.

           

          as for defining smaller contact areas, you've found the method, split lines. you don't necessarily have to make them the size of the button, you could make them just bands.

           

          here are my suggestions:

          1. try surface to surface and node to surface, it may make a difference

          2. it looks like your part is all one body. consider breaking into multiple bodies. i THINK i remember an older version having some trouble with self contact.

          3. improve the mesh in the area of contact, that may be part of the equation here.

          4. try some other models, determine if this is really a software problem or a part specific problem

          5. try different combinations of splitlines. swap the source and target, global vs contact sets.

          6. switch between FFE and direct sparse. but in this case, DS is the right solver.

           

          overall, your approach seems reasonable. so there may be an issue here. but like you've seen there are ways around it. and in this case it isn't a fact of results being wrong but rather that the automated contact definitions arent' working exactly correct. in other FE programs you'd have to build those connectinos by hand, so even with the workaround, you're far ahead.

           

          also i want to make one comment about curvature based mesh. the mesher is faster in curvature mode (multi-threaded). but if you have the same number of DOF as a standard mesh, solve time will be the same. you are likely creating less elements if you're seeing faster solve time.