Contact 1

[LTB]

Good afternoon,

I liked that I could solve a problem that I have in Abaqus. The model I'm preparing can be downloaded at this link:

http://ftp.ua.pt/incoming/fghj/.

As you can see through the file is a model consisting of eight cells of cork that are restricted and are under the action of a shift that originates compression. My problem is related to the fact that the top faces of the cells intersecting the lower cells, which can not happen. Can anyone help?

Thank you for your attention

Greetings

 

[rstupplebeen]

File not there. Could you post it directly to this forum?

Rob Stupplebeen

 

[LTB]

Hello!

Sorry about that, but there must have been a server error.

Now available.

Greetings

 

[rstupplebeen]

First try turning on nonlinear geometry (NLGEOM) and reduce the initial step to 0.01. The displacement would turn the model inside out you should reduce that to a realistic value. The front and backs of the honeycomb core possibly should be constrained in the Z. I would model this with brick elements because of the large deformation, bending and self contact. I hope this helps.

Rob Stupplebeen

 

[LTB]

And considering the non-linear geometry, reducing the step to 0.01 and considering brick elements that you think that the top surface of a cell by contacting the underside there is no intersection?

Note: As I consider the elements brick?

Greetings

 

[rstupplebeen]

Please rephrase and/or post a picture.

Rob Stupplebeen

 

[LTB]

Can you open the file right?

It was really important that could do that ... So you only importer was able to implement your ideas and send me the model through a link?

Greetings

 

[rstupplebeen]

I did open the file and ran it did the tweaks minus the brick mesh and the Z constraint. It did partially solve. It got a "step size is too small" error. Attached is the *.INP file zipped up. I can not send the *.CAE because I am on a newer version.

I would create this solid geometry in a CAD package and import it into CAE.

I hope this helps.

Rob Stupplebeen

 

[loki3000]

Hello i have a simple model to model with contact properties (it's more or less an exercise, i think). the only problem is, that the load is pointed in such way that we get tension in the place of the contact surfaces (three lines as seen in the image). i was told that there are some formulations that can handle tension but was unable to find anything (i found the "hard contact" option, the no separation after contact and such) to get a converged solution.

i have attached a picture and an inp (hopefully i will be able to attach both) of the problem.
what kind of contact property (interaction) do i need to get a solution?
i managed to do that with "tie", but i don't think that's ok, since you basically get a rigid body that way.

 

[loki3000]

and the inp file. the error i get are negative eigen values and num. singularities

 

[rstupplebeen]

Your first try with a "tie" constraint will simulate perfect bonding of the 2 parts. It looks like you could merge the 3 solids together and achieve the same results. If you are trying to simulate a bond that could fail then look into cohesive and damage. I hope this helps.

Rob Stupplebeen

 

[aouici]

I am studying in 2nd year engineering doctorate, I have a practical example in the field machine (working hard) model by Abaqus. Thanks

 

[iyj]

Dear All

Before I start my question, I would like to appreciate the efforts of people helping each other, thats reallt great.

My question is that I am trying to model a 2D contact problem (indentation of a steel sphere on rectangular Alimunium plate). Now as I am a beginner. I have modeled the plate with Aluminium properties and steel with its properties. Made contact with each other and defined steps and applying displacement load on top of the indentor. The application runs successfully. But what I am trying to achieve is that it shows the deformation when applying load on it. But i also want to see when we remove the indentor how much deformation remains after unloading. So the problem is unloading and do i have to create a seperate step for that, and if i do, both part will still be in contact so how do i do that.

please do help me in this regard as I am really struggling.


Thanking you in advance

 

[rstupplebeen]

For future reference this should be in a new thread.

You can do this a couple of different ways. Create a new step and have the displacement go back to zero. Or, Create an amplitude that the displacement references that ramps from 0-1-0 for time points 0-.5-1.

You will need to include plastic deformation for the aluminum plate otherwise you should have no residual stresses.

I hope this helps.


Rob Stupplebeen

 

[iyj]

Dear Rob

I thank you alot for these helping comments and suggestions. I will try these out and will let you know the outcome too. Once again thanks alot and really appreciate your effort.

Best Regards

 

[iyj]

Dear Rob

It really worked I am so happy, thanks alot really thanks. While attempting the case there was a minor issue and that was when it was unloading it was not going to its original place. like fist displacent i gave was (U2= -0.05, ), and the second BC was U2 = 0, rest remain unchanged. i wanted to to see the final force comning back to zero. The plastic thing really worked, thanks.

Please do let me know where i am wrong.

Regards

 

[iyj]

Dear Rob

In the second step which is the unloading, instead of force going back to zero it actually increases. I already gave the displacement(U2=0) for the final step, but still this problem occurs. Do I have to disconnect both the parts so there is no contact in between them. if yes How do I do that?. Can you please let me know.

Or if not plz can you correct me where I am wrong

Thanking you in advance


Regards