contact problem in Abaqus

[optimus2007]

problem:

body X contacts body Y (both iron and rubber on the edge), e.g. rubber on rubber . In visualization it can be seen that body Y go through body X. Contact definition is hard and srface-to-surface.

How can I fix this problem?

thanx for helping

 

[Jlog50]

Is this just a visual problem? Are you results strange? You could try to remove overclosure in the interaction module.

 

[optimus2007]

in visualization. the rubber edge of body Y deforms and goes through body X while getting in contact.

 

[optimus2007]

I have forgotten to say that the job completed sucessfully.
Do you mean that this penetration is just a visual problem in Abaqus?

 

[Fabi0]

What kind of integration rules do u use? If penalty, u must know that this kind of rule allow some small overclosure between contact surfaces.

Anyway, u can try to run again the job with the contact diagnostic tool on (step, output, diagnostic....or something like ). In this way, you can have a complete report of overclosure (if exist) in the .msg file and in the .odb.

If pressure are ok, maybe it's only a visualization problem.

Fabi0

 

[portliner]

If both the iron and rubber are modelled as elastic with realistic modulus the stiffness martix will probably be ill-conditioned due to large differences in stiffness in the structure. If the iron parts are much stiffer then the rest model them as rigid bodies.

/Stig

 

[Jlog50]

Optimus2007, yes, sometimes edges look flat even though you know that are perfectly round geometrically.

Fabi0, when using penatly method to define tangential friction between surfaces, you mention you this allows for some overclosure. Can this be overcome by selecting to remove overclosure in the interaction module?

Thanks

 

[Fabi0]

I was talking about penalty in the constraint enforcement method (under normal behavior) but a quick reading to documentation let me believe it works the same. Anyway, what do you mean with "remove overclosure" ?

Do u mean ---> Edit Interaction --->"adjust to remove overclosure" ?

If you do, the answer is no: u can use this option only to remove initial overclosure, but during analysis the overclosure is ruled by the constrain enforcement method. Penalty had a "relaxed" formulation, so it is cheaper of computational time, but only because penalty allow nodes of the slave surface to penetrate into the master surface for a small amount of overclosure.

Fabi0

 

[optimus2007]

Thanx for the comments.

job completed succesfully by choosing small sliding,

but if I choose finite sliding it aborts after 30- 40 %
In finite sliding there is no penetration.
so how can i fix the problem?

 

[Fabi0]

It's strange, finite sliding should be a more general way to simulate sliding in contact, so we should expect that small sliding fails, not finite sliding.

First of all: what kind of surface discretization did you use in creating model? Surface to surface or node to surface?

.msg file told you something? Any singularity warning?

Body X and Body Y had the same contact areas? I mean, there is contact along the perimeter of the two bodys? (In other words, do you have two aligned cubes with the same side length that make contact on a square face?) In this case you may have chattering problem, where finite sliding is less efficient than small sliding.
You should run analysis with contact diagnostic option, so u can see if contact point couple passes from close to open.

Fabi0

 

[optimus2007]

it is a 2- d model.

surface to surface

error: max. penetration in some nodes