dear friends
I was trying to study problems with finite friction involving indentation of a thin layer bonded on a substrate. As you can see from the theory
https://www.researchgate.net/publication/375415770
there are large differences between frictionless and infinite friction cases both at punch/layer and layer/substrate interface. However, particularly for incompressible materials, in ANSYS the contact results with finite friction are unreliable and I gave up in trying to setup contact stiffness parameters to find reasonable results --- here we know analytically some limit behaviour for frictionless and very high friction results, so we can check the intermediate case.
Do you think other FEM code could do better? To setup the mesh for the flat punch is extremely simple, so we could try with your help in other codes.
thanks
Mike
Abaqus might works better than Ansys in dealing with friction. We have tried the sphere indentaion of thin film on a substrate, the abaqus restults fit quiet well with Dimitriadis's theory.
Thanks . Can you tell me a refernence to dimitriadis ?? Was it also a theory eith finite friction? And your results too?
Xiaoming Liu Interesting. Did you publish the results which can be referred to? Did you also include the comparison of results calculated by LD-DYNA?
Hi, I tend to agree that Abaqus might be a better option for contact simulations (we have a lot of experiences in nanoindentation simulations with varying of the coefficients of friction)... However, the basics should be same in Ansys... You mentioned that You were changing the contact stiffness parameter without any success - have You tried a different contact formulation? Langrange or Augmented Lagrange could give You a better results, since (at least for pure Langrange) there is no surface penetration and the results should be as close to reality as possible.
@S.-G. Li, we have not compared with LD-DYNA, but I think the result from DYNA will be the same. The results have not been published, we are still working on it.
we have not compared with LD-DYNA, but I think the result from DYNA will be the same. The results have not been published, we are still working on it.
Shaoguang Li
Dear Michele Ciavarella ,
I studied the indentation problems on FGM using ANSYS APDL involving elastoplastic behavior. You can refer to the bellow paper
Article On the Indentation of Elastoplastic Functionally Graded Materials
the code I implemented is attached you can use it as a draft for your study.
Hope this can help you
dear Kouider Bendine but was your case with finite friction? I don't see friction coefficient in your file..... Thanks
Xiaoming Liu can you please tell me a reference to Dimitriadis's theory?
In this paper by E. Dimitriadis, Determination of elastic moduli of thin layers of soft material using the atomic force microscope，Biophysical Journal，2002, Dimitriadis proposed a contact modal for spherical indention of thin film. Michele Ciavarella
In the abaqus, some Fortran subroutines can be created to consider the third body layer, you can refer to the user's manual for details. But we prefer to develop the code by ourselves.
Dear Michele Ciavarella ,
in order to insert the friction please change the contact171 element to contact 172 in the code I sent. The friction properties can be assigned using the command TB. Please refer to the ansys help for more details or use the following link
https://www.mm.bme.hu/~gyebro/files/ans_help_v182/ans_elem/Hlp_E_CONTA172.html
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