Problem with interface bonded contact

1

The image shows a model for static analysis (1/4 section of two stacked cylinders). The lateral sides and bottom are frictionless-constrained against normal movement. A negative pressure is applied to the top of the top cylinder. The interface between the two cylinders is bonded. (I will try to post an image link separately.)

Notes –

  1. The model was constructed in Mecway FEA. (I can post a link if needed.)
  2. The mesh is the default. (I realize the mesh is rather coarse but I want to resolve, in general, the problem of nodal mismatch at interface surfaces.)
  3. The H200c_static_bonding_static_load.inp file was generated by Mecway FEA. Dropbox - H200c_static_bonding_static_load.inp - Simplify your life

When I run ccx on this inp file I get an error –
*ERROR in cascade: the DOF corresponding to node 306 in direction 1 is detected on the
dependent side of a MPC and a SPC

This error is given in the calculix source code – https://stuff.mit.edu/afs/athena/software/calculix_v2.7/CalculiX/ccx_2.7/src/cascade.c (search there for “ERROR in cascade: the DOF”).

Node 306 is located at (X,Y,Z) = (0,50,10)mm which is a corner of the bottom surface of the top cylinder at the interface between the two cylinders.

If I delete the constraints on the lateral sides then the analysis finishes but, of course, the results are incorrect.

Since this model’s configuration should not be uncommon, I think there should be a solution. (After resolving for static analysis I would then proceed to modal analysis.)

Thanks,
Don C.

========================================================================

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CalculiX comes with ABSOLUTELY NO WARRANTY. This is free
software, and you are welcome to redistribute it under
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You are using an executable made on Sun, Jan 19, 2020 10:23:46 PM

The numbers below are estimated upper bounds

number of:

nodes: 610
elements: 238
one-dimensional elements: 0
two-dimensional elements: 0
integration points per element: 4
degrees of freedom per node: 3
layers per element: 1

distributed facial loads: 37
distributed volumetric loads: 0
concentrated loads: 0
single point constraints: 282
multiple point constraints: 307
terms in all multiple point constraints: 5815
tie constraints: 0
dependent nodes tied by cyclic constraints: 0
dependent nodes in pre-tension constraints: 0

sets: 10
terms in all sets: 569

materials: 2
constants per material and temperature: 2
temperature points per material: 1
plastic data points per material: 0

orientations: 0
amplitudes: 2
data points in all amplitudes: 2
print requests: 0
transformations: 0
property cards: 0

STEP 1

Static analysis was selected

Decascading the MPC’s

*ERROR in cascade: the DOF corresponding to
node 306 in direction 1 is detected on the
dependent side of a MPC and a SPC

========================================================================

2

Here is the model’s image file –

H200c_static_bonding_static_load_1a
H200c_static_bonding_static_load_1a1056×839 148 KB

3

you get these error if you use the node 2 times.
for example if you use it for boundary and for the bounded contact !?

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4

Yes, I understand that may be the problem. However, what is the solution? If I eliminate some of the boundary conditions at the interface (those that interfere with the contact conditions) then the boundary conditions wouldn’t be correct. Alternately, if I eliminate some of the contact conditions at the periphery of the interface (those that interfere with the boundary conditions) then the contact conditions wouldn’t be correct. Potentially I could do one of these by editing the inp file. However, I would first have to identify the offending nodes, probably by clicking on each in the model. This would be extremely tedious, especially where there are a large number of interfaces and a dense mesh (not like this simple model). There must be a better way.

Note that the boundary conditions and bonded contacts were applied by selecting surfaces for application, not by selecting groups of nodes.

5

You could try a tied surface-surface contact. The penalty stiffness in that case is very high. I think it is written in the documentation.
Kindly regards
Markus

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