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Frictionless contact in simulation

johannes_wjohannes_w Member Posts: 25 PRO
Good day,
I just watched the webinar of onshape simulation with @GregBrown and Christopher Gromek. Thank you for the presentation, really cool stuff!
What really stuck out to me though is the fact, that there isn't a way to set a frictionless contact, only mate driven contacts. Am I missing something here?
According to my experience in simulation, this type of contact is often needed. Wrongly assigning bonded contacts, can lead to different results.

Or is interference between two bodies natively prevented, and not using any mate gives me the desired contact?
Frictional contact would be the next logical step but I think you already have answered this one in the webinar.

Thank you!


  • GregBrownGregBrown Member, Onshape Employees Posts: 79
    edited May 31
    The interaction between instances is fully defined by either:
    1) all mates between the instances 
    2) If "Connectivity method and visualization" (in the Simulation panel) is set to "Bond all touching faces" or "Mates and touching faces" - then touching faces that have no mates will be fixed, whilst for faces with mates, the mates are respected

    In case 1) the degrees of freedom will be inferred from the mate
    In case 2) the interaction is fully fixed
    If you want a frictionless contact between two planar faces then you can use planar mate. The instances will stay in contact (we would not allow separation, as this is linear static stress...

    That said, any degree of freedom between two bodies, as allowed by the mate, will be frictionless. A big tip here, if you only intend a small/given portion of a body to participate in the interaction then you can use the Simulation connection option in the mate, and select the appropriate face(s).

    Finally, you can use the connectivity visualization to ensure the bonding, or otherwise, between instances is as you intend.

    PS Here is a simple frictionless example (planar mate in this case)

  • johannes_wjohannes_w Member Posts: 25 PRO
    Thank you for your comprehensive answer, I appreciate your time!
    As for the different bonding settings, I checked out the webinar beforehand and understand the principle of this so far.
    I should have explained my question better, I was specifically referring to the frictionless contact as it is defined in Ansys. In solidworks it is called No Penetration Contact. So basically, preventing interference between faces but not constraining them in any other way:

    You already mentioned in your answer, that you wouldn't allow separation of faces. That is exactly what I meant. In my humble opinion, allowing separation is a very important contact option. There have been many cases in my experience, where just letting two faces slide along each other would create an unrealistic simulation scenario.
    Is a no penetration contact planned in the near future?

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