Bonded contact elements

[AidanMcConneheyOVT]

I'm sure this is just a simple matter of an attribute that I'm missing, but when using gcgen I'm not sure how to apply bonded contacts as opposed to frictional.

As an example, here's an implementation that leverages the setup used in the ANSYS documentation examples:

from ansys.mapdl import core as pymapdl

# Start MAPDL session
mapdl = pymapdl.launch_mapdl()
mapdl.clear()
mapdl.prep7()

# === Create Lower Volume ===
vnum0 = mapdl.block(0, 1, 0, 1, 0, 0.5)
mapdl.et(1, 187)
mapdl.esize(0.1)
mapdl.vmesh(vnum0)

# === Create Upper Volume ===
mapdl.esize(0.09)
mapdl.et(2, 186)
mapdl.type(2)
vnum1 = mapdl.block(0, 1, 0, 1, 0.50001, 1)
mapdl.vmesh(vnum1)

# === Automatically Generate Contact Elements ===
mapdl.nsel("s", "loc", "z", 0.5, 0.50001)
mapdl.esln("s")
mapdl.gcgen("NEW", splitkey="SPLIT", selopt="SELECT")

# === Apply Boundary Conditions ===
mapdl.finish()
mapdl.run("/SOLU")

# Fix bottom surface in all directions
mapdl.nsel("s", "loc", "z", 0)
mapdl.d("ALL", "ALL", 0)

# Apply lateral force on top surface
mapdl.nsel("s", "loc", "z", 1)
mapdl.f("ALL", "FX", 1000)

# Solve
mapdl.allsel()
mapdl.solve()
mapdl.finish()

# === Post-processing ===
mapdl.post1()
mapdl.set(1)

# Plot deformed shape and contact status
mapdl.plnsol("U", "X")       # X displacement
mapdl.etable("CONTSTAT", "CONT", 19)  # Contact status flag (SSTAT)
mapdl.pltab("CONTSTAT")     # Plot contact status

My current theory is that the code is failing due to it being not fully constrained in the contact region.

[mikerife]

Hi @AidanMcConneheyOVT
There are a few things going on here:

1. There is not material model defined for the blocks
2. We change the contact interaction, for general contact, by way of the TB command. I used material ID of 2 for this.
3. There is a gap between the two blocks so the contact pinball size would need to be large enough to cross the gap. I cheated and created the two blocks with no gap.
4. I created two nodal components, one on each face of the block that will come into contact. And used these in the GCDEF for ease of use.
5. The ETABLE command has '19' instead of 'stat'.
6. The element table plotting command is missing the 'e', should be pletab. And use the 'avg' option.

Here are the non-postprocessing changes. This will solve.

mapdl.clear()
mapdl.prep7()

# define linear material
mapdl.mp('ex', 1, 1e7)
mapdl.mp('nuxy', 1, 0.3)

# === Create Lower Volume ===
vnum0 = mapdl.block(0, 1, 0, 1, 0, 0.5)
mapdl.et(1, 187)
mapdl.esize(0.1)
mapdl.vmesh(vnum0)

# create node component of contacting face
mapdl.nsel('s', 'loc', 'z', 0.5)
mapdl.cm('node_contact', 'node')
mapdl.allsel()

# === Create Upper Volume ===
mapdl.esize(0.09)
mapdl.et(2, 186)
mapdl.type(2)
vnum1 = mapdl.block(0, 1, 0, 1, 0.5, 1)
mapdl.vmesh(vnum1)

# create node component of contacting face
mapdl.esel('s', 'type', '', 2)
mapdl.nsle()
mapdl.nsel('r', 'loc', 'z', 0.5)
mapdl.cm('node_target', 'node')
mapdl.allsel()

# === Automatically Generate Contact Elements ===
mapdl.gcgen("NEW", splitkey="SPLIT", selopt="SELECT")
mapdl.gcdef('auto', 'node_contact', 'node_target', 2, 2)
mapdl.tb('inter', 2, '', '', 'bonded')
mapdl.allsel()

mike