General Mechanical

General Mechanical

‘Contact element x (real ID y) status changes abruptly …. no contact’. How to locate this element?

    • Rameez_ul_Haq
      Subscriber

      So I am struggling with a problem in my contact non-linear analysis in Static Structural Module. In my model, I have developed many frictional contacts, and some of them are near open. During the first load step, I get this warning, which goes as:


      WARNING

      Contact element 'x' (real ID 'y') status changes abruptly from contact (with target element 'z') --> no-contact.


      So I don't know how to navigate myself to this exact contact element 'x', and target element 'z', since I have several non-linear contacts so I just want to know which one is loosing contact during the analysis. The solver stops abruptly after this warning, which means that loss of this contact is actually causing a Rigid Body motion.

      Secondly, there is an error message as well after this warning, which goes as:


      ERROR

      The value of UY at node 's' is 'r'. It is greater than the current limit of 1000000. This generally indicates a rigid body motion as a result of an unconstrained model. Verify your model is properly constrained.


      Now, when I try find this node 's' in my mesh model, I am unable to locate this node at all. I don't know where is this node present within my model. Maybe some extra nodes are created during the analysis, which are not present in my mesh model so I may not be able to find this node at all. But then how can I know which node (or basically, which body in my model) is undergoing Rigid Body motion.

      Need help with these issues, please.

    • John Doyle
      Ansys Employee
      I am assuming you are working in WB-Mechanical.
      You could create a named selection and use the Worksheet mode to specify the mesh element id.
      However, I am not sure that is the best way to troubleshoot this model. The contact is failing, causing the model to be underconstrained and parts are flying off as a result.
      You might have considered this already, but if not, perhaps you could insert a Contact Tool under the Connections Branch and "generate Initial conditions". This should give you a summary of the initial status of all the contact pairs.
      Look for the ones that are initially open and change the model so that they are initially closed. It might require modifying the original geometry, if there are very large gaps; but you might also be able to use adjust to touch, if these are just nuisance gaps. I am assuming the model is properly constrained in all other respects.If not, then you need to fix this as well.

    • Rameez_ul_Haq
      Subscriber
      thankyou, first of all.
      Just assume everything else is fine, but just the contact is getting lost during the analysis as a result of loading condition. So I was not able to navigate myself to this exact contact/target elements and also the node number (of that part of the body which is experiencing Rigid Body motion). I tried searching these elements and node in my mesh model, but there didn't exist any.
      So I would be trying what you suggested You could create a named selection and use the Worksheet mode to specify the mesh element id.
      Can you kindly tell me how can I enter this element ID into the named selection that I have made?
      Plus, I think this will only work if the elements and/or node already exist within the mesh model; if it doesn't (like these can be extra contact and target elements, or extra nodes created by the solver during analysis which are not a part of the mesh model) then I don't know how to locate them.
    • Rameez_ul_Haq
      Subscriber
      ,I would be delighted to get a reply from you on the previous comment I made :)
    • Rameez_ul_Haq
      Subscriber
      ,I would gladly welcome a reply from you on this issue, please.
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