solids4foam/foam extend contact modelling
Dear foamers,
I was wondering about the options for modelling contacts in foam extend and also in solids4foam. I found the FVM approach for this very interesting... For example, which condition will be the "equivalent" to a bonded contact (like for example in ANSYS Mechanical)? Thanks a lot in advance |
Currently, solids4foam treats contact with a penalty procedure, which is fundamentally similar to the node-to-segment approach from fem. The procedure is suitable for small and large deformations and for rigid-deformable contact.
In bonded contact, bodies are glued and there is no sliding and separation. I think that this behavior can be easily achieved using GGI or AMI, so there is no separate implementation for bonded contact. |
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Thanks for the suggestion :) |
Hi!
I have also been involved with penalty vs bonded contacts recently. I am working on a similar problem and have as reference results from running simulations with bonded contact. Have you succeeded mimicking the bonded condition with foamextend / solids4foam ? @iBatistic I have been reading your recent work :D: A finite volume penalty based segment-to-segment method for frictional contact problems, Ivan Batistić a, Philip Cardiff b, Željko Tuković. It seems that this approach is better at controlling penetration. Does the segment-to-segment approach mean to replace the GGI ? Is this the current underlying mechanism for solving the contact penalty in solids4foam v2.0 ? I read in related threads that to handle numerical instability, low relaxationFactors (in the firction & normal Models) should be used. But they allow more penetration so it diverts from the bonded condition. I was wondering if with the segment-to-segment model is more stable and therefore, we don't need to increase the penetration gap. Thanks for sharing ! |
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It is currently unavailable in solids4Foam, but I guess that will be anytime soon. Quote:
If you want to model bonded contact (no sliding and no separation) why not use the multi-material interface treatment described here (it is implemented in S4F): Finite-volume stress analysis in multi-material linear elastic body (Tukovic, Ivankovic and Karac) |
Excellent. I hope the segment-to-segment gets integrated soon and used. Sounds very interesting. Thank you very much for making it available !!
In my case, I treat the geometry by regions and mesh each body independently so contact regions are not conforming. I thought the only way of imposing the contacts was through the normal and friction models in the D / DD files using the relaxation and penalty factors for penetration. Thank you for the paper that you suggest, I will have a look! ...Although I am starting to think that bonded with non-conforming contacts doesn't seem feasible... |
In bonded contact, the contact area is known in advance, which means that the contact loses its main source of nonlinearities (this fact is useful for implementation). Currently, you are using a boundary condition that is developed for the unknown and evolving contact area.
Solids4Foam can use cell zones to treat mesh zones as different materials, but I think that the same procedure with non-conforming separate meshes is not available. Probably should be best to implement a separate boundary condition to treat bonded contact. |
yes, that's what I figured... I am currently using cfMesh to generate the meshes and I refine through regions (patches) which have identical .stl files except for the triangles orientation. The resulting meshes in the contacts have almost the same facets. From that, I think it is possible to have an almost conforming contact. I will try implementing the bonded contact.
Thanks for the ideas!!!!! |
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Recently, when I used the contact model in s4f to calculate my case, From function void newGGIInterpolation<MasterPatch, SlavePatch>::calcAddressing() in file LnIclude/newGGIInterpolationWeights.C at line 293 The master projected polygon was CM instead of CCW. This is strange... appeared. I am curious why this problem occurs and what can be done to solve it? My case is about the extrusion of a ball on a V-shaped surface in plane strain state. Hope you could give me some advice. Best, Young |
Hi Youngxl, that is strange, I never got that warning, it occurs because the boundary face points are oriented in the wrong direction. Can you share the case?
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