Possible bug using *Contact print

I have prepared a model of two parts in contact as seen in the bottom image (I am using 2D plane stress for simplicity reasons). The problem is, that when I add a *Contact print card the simulation ends without the results - fails, but when I remove the *Contact print card the simulation ends successfully with results. This only happens for the node-to-surface contact and the output variable CF:

*Contact print, Master=Internal_Selection-1_Cp-1_Master, Slave=Internal_Selection-1_Cp-1_Slave

The input file can be downloaded at: Dropbox - Contact_Err.inp - Simplify your life

I have tested the simulation on Windows 10 using CalculiX 2.18. Can somebody confirm the problem before we bother Guido?

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It seems that it’s not a bug but rather a limitation. Apparently, the print of contact forces can’t be requested for a node to surface contact. Quoting the documentation:

The quantities CF, CFN and CFS represent the total force, total normal force and total shear force acting on the slave surface, respectively, for a selected face-to-face penalty contact pair.

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I agree that it is a limitation but the problem is that the simulation starts, goes through all iterations to find an equilibrium solution and then fails to write the results. Any results.

As I see it, other results (U, S, E, …) should be saved for the user not to lose time.

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That’s right, a limitation shouldn’t be handled this way, especially since it can be very confusing for the user. The solver should produce an error or warning message to make it clear what’s going on. And, as you said, the best way would be to make the solver warn about invalid output request, ignore it and carry on with the analysis writing other results.

@dhondt Could you consider fixing the current behavior in this regard ?


That is exactly what I had in mind. Thank you.