General Mechanical

General Mechanical

Default value for Penetration Convergence Tolerance and Normal Stiffness of a contact?

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    • Rameez_ul_Haq
      Subscriber

      For all the contacts (Non-Linear as well as Linear), I see an option of penetration convergence tolerance and also normal stiffness of the contact. I want to know the default values used by the solver for each of these, and for each of the contact.

      I am asking this because sometimes, my solution is unable to converge at the contact region and I want to play with the Penetration Convergence Tolerance and Normal Stiffness values in order to make it converge. However, if I randomly input a very high or very low value, then the solution results might not be accurate at all.

      Moreover, does the penetration convergence tolerance also needs to be met for the solution to converge at the contact region even if I am using a linear contact?

    • Rameez_ul_Haq
      Subscriber
      , I would be glad if I could get help on this one please?
    • Emperor
      Subscriber

      I asked myself this question not long ago. If you look at this link "Table 3.1: Summary of Real Constant Defaults in Different Environments" there are default values. You can change them with the 'RMODIF' command that I use a lot since this discovery
    • Rameez_ul_Haq
      Subscriber
      thank you for navigating me through that table. So it means that we shouldn't input any value manually, we should only play with the factors for normal stiffness and penetration convergence tolerance since we still don't know the value used by ANSY but we just know the default factors.
    • Emperor
      Subscriber
      yes I often played with the different factors for the normal stiffness. For penetration some formulation accept penetration as the increased Lagrange and pure penalty formulation. Others do not accept penetration as Normal Lagrange. So in case you choose for example a Normal Lagrange formulation you will not have to enter a value for penetration.

      Let me show you the pictures below to illustrate what I am saying:




    • Rameez_ul_Haq
      Subscriber
      ,can you also please navigate me to the document from where you attached this picture? Thank you.
    • Emperor
      Subscriber
      This document is a pdf that I have in my documents. It is a lesson on contacts. I can't put the document on the platform, but I can send it to you by e-mail if you want
    • Rameez_ul_Haq
      Subscriber
      ,are you talking about Ansys 9.0 Contact Guide?
    • Emperor
      Subscriber
      I just found in Ansys help my pdf, you can look at this link
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