Get contact penetration of selected nodes on a line

[herttim]

Hi all,

I would like to obtain contact penetration infos of a CONTA178 data set.
I´ve used the following prompt but unfortunatelly it´s not working.

mapdl.allsel()
mapdl.csys(1)
mapdl.lsel("ALL")
mapdl.lsel("S", "NDIV", vmin=ns-1)
mapdl.lsel("R", "LOC", "X", vmin=di/2+o-q+0.001, vmax=di/2+o-q+0.002)
mapdl.nsll("S", 1)
mapdl.post_processing.plot_nodal_values(item='cont', comp='pene')

There is the following output:

TypeError: nodal_values() got multiple values for argument 'comp'

What´s the reason for that? It is possible to plot all contact information but not only the penetration.
Or is there an other way to obtain the penetration. I need the penetration for further calculations.

Thanks in advance.

[mikerife]

Hi @herttim
There are a few answers here as when I see "need X for further calculations" I'm assuming you need to capture the value and not a plot. Anyway Contact 178's don't support plotting contact values with the "cont" items as the other contact element types do. The name of the value is USEP (go figure) where negative values represent a gap and positive values penetration. And are stored on the third NMISC. So the following should plot these:

mapdl.esel('s','enam','',178)
mapdl.nsle()
mapdl.post_processing.plot_element_values(item='nmisc', comp=3)

You could capture the values for later calculations using:

contact_penetration = mapdl.post_processing.element_values(item='nmisc', comp=3)

Attached is a Jupyter Lab notebook of MAPDL Verification Manual 27 to test on.

Mike
VM27.zip

[herttim]

@mikerife Thanks for answering my question! That helped me a lot 👍

Unfortunately, I'm still stuck on determining the contact penetration for a selected line and its elements.
To explain: Two bodies are built with SOLID185 elements and connected by CONTA178 elements. I would like to determine now only the penetration at the CONTA178 elements at selected lines.

I thought it would work that way, but unfortunately it doesn't:
mapdl.allsel()
mapdl.lsel("S", "LINE", vmin=4)
mapdl.nsll("S", 1)
mapdl.esln("S", 1)
mapdl.esel("R", "ENAM", "", 178)
mapdl.eplot(vtk=True)
contact_penetration_r = mapdl.post_processing.element_values(item='nmisc', comp=3)
print(contact_penetration_r)

Or is it only possible to output all CONTA178 elements at once?

Best regards
herttim

[mikerife]

Hey @herttim I think that the line

 mapdl.esln("S", 1)

is the culprit. Try selecting the elements if any of the nodes are selected with

mapdl.esln("S", 0)

instead. Mike

[herttim]

Now, it´s is working! Thank you for the support! 🥇