LS Dyna

LS Dyna

Contact issue in Pre-stress explicit

    • Haiquan
      Subscriber

      Hello

      I am doing a pre-stress grommet pull-out simulation. First step is to do interference fit, second step is to pull out the grommet. Unfortunately, it is difficult to obtain convergence in second step with implicit method. So I use explicit to perform a quasi-static for the second pull-out step. 

      But I encounter contact issue. The contact works well in pre-stress step, but in explicit, the contact seems fail to work shortly after the explicit starts. I didn’t change any setting in the explicit pre-stress. Below figures show the model, the penetration in explicit, and the contact setting, I also attach the ANSYS 2020 R1 file for this issue.

      Thank you in advance!


    • Ram Gopisetti
      Ansys Employee
      why is PA6 is initially penetrated into the Grommet ?, is this by design ?. This should work in the implicit given your boundary conditions are reasonable. Perhaps working with the steps might help you. Ansys employees may not able to open your attached files, we encourage you to post your work inline to the text.
      cheers, ram
    • Haiquan
      Subscriber
      Thank you very much for your comment! The penetration design between PA6 and grommet is for sealing, we need pressure to avoid leakage. I output the text .inp for implicit, but it does not allow me to paste the 8MB size text directly.

    • Ram Gopisetti
      Ansys Employee
      can you post the Initial contact status and why is the liner penetrated as if no contact defined as I see mesh intersection as fused. Usually, with the contact defined, the mesh and bodies will not fuse with each other and will maintains some sort of separation. Post down your response.
      cheers, Ram
    • Haiquan
      Subscriber
      Thank you very much for your comment! Below is the contact information in the static interferemce fit step


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