# Problem with interface bonded contact **URL:** \ **Category:** Uncategorized\ **Created:** [April 19, 2021, 4:08pm UTC](https://calculix.discourse.group/t/problem-with-interface-bonded-contact/544 "2021-04-19T16:08:08Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![dculp](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@dculp](https://calculix.discourse.group/u/dculp)\ **Post date:** [April 19, 2021, 4:08pm UTC](https://calculix.discourse.group/t/problem-with-interface-bonded-contact/544/1 "2021-04-19T16:08:09Z")
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](https://www.dropbox.com/s/icit2vhafsswizh/H200c_static_bonding_static_load.inp?dl=0) 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](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. # ======================================================================== CalculiX Version 2.16, Copyright(C) 1998-2019 Guido Dhondt CalculiX comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions, see gpl.htm * * * 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 ======================================================================== ---
**Author:** ![dculp](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@dculp](https://calculix.discourse.group/u/dculp)\ **Post date:** [April 19, 2021, 4:10pm UTC](https://calculix.discourse.group/t/problem-with-interface-bonded-contact/544/2 "2021-04-19T16:10:06Z")
Here is the model’s image file – ![H200c_static_bonding_static_load_1a](https://global.discourse-cdn.com/free1/uploads/calculix/original/1X/ec7b30f6adeca0c75269a7e50a3f0f7bb26681a3.jpeg) ---
**Author:** ![dichtstoff](https://avatars.discourse-cdn.com/v4/letter/d/dec6dc/32.png) [@dichtstoff](https://calculix.discourse.group/u/dichtstoff)\ **Post date:** [April 19, 2021, 4:42pm UTC](https://calculix.discourse.group/t/problem-with-interface-bonded-contact/544/3 "2021-04-19T16:42:57Z")
you get these error if you use the node 2 times. for example if you use it for boundary and for the bounded contact !? ---
**Author:** ![dculp](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@dculp](https://calculix.discourse.group/u/dculp)\ **Post date:** [April 19, 2021, 6:25pm UTC](https://calculix.discourse.group/t/problem-with-interface-bonded-contact/544/4 "2021-04-19T18:25:44Z")
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. ---
**Author:** ![MarkusS](https://avatars.discourse-cdn.com/v4/letter/m/41988e/32.png) [@MarkusS](https://calculix.discourse.group/u/MarkusS)\ **Post date:** [April 23, 2021, 3:54am UTC](https://calculix.discourse.group/t/problem-with-interface-bonded-contact/544/5 "2021-04-23T03:54:03Z")
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