Contact between a rigid body and a deformable plate

[jingansong]

Hi everyone,

I'm trying to do a contact simulation between a rigid body and a deformable plate. I used contact pair interaction. The job failed in the middle. I checked the .odb file, the plate didn't deform a lot, while the mesh changed a lot (I'm not sure if it's correct to describe it like this). And the temperature result seems to be too high (I don't know if it's caused by the weird mesh change). Can someone please take a look at my files and give me some tips? Thank you very much!

 

[IceBreakerSours]

Describe the problem clearly, tell us what you have done and observed, tell us the warning/error messages you see .. and so on. Someone may solve your problem by opening the inp but you won't learn how to resolve your errors on your own.

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[jingansong]

I created a rigid body and a deformable plate. I fixed the rigid body and applied velocity on the deformable plate. A dynamic temp-disp explicit step was used for the simulation. In the contact property I specified friction coefficient and heat generation. And I used contact pair interaction. The warning message says that some nodes participate in boundary condition as well as in the kinematic contact definition. The boundary condition will override the kinematic contact constraint. It suggests me to use the penalty contact algorithm. The error message says 1) Zero or negative mass in element; and 2) time increment has become negative??

So now I have followed the suggestion to change the kinematic contact to the penalty contact. There was no error happened during the simulation. However, the weird mesh change thing (I captured the original mesh and the after simulation one) is still there. I really don't know why this happened. It's very helpful and appreciated if someone give me some tips.

https://www.dropbox.com/s/1soa13m53ivor8s/original mesh.PNG

https://www.dropbox.com/s/w5bm2y6p6lesnb3/mesh after simulation.PNG

 

[jingansong]

Here are the two captures. Thanks!

 

[IceBreakerSours]

".. some nodes participate in boundary condition as well as in the kinematic contact definition.."

Think about it. You are asking some nodes to do two separate things at the same time.

Are you new to this forum? If so, please read these FAQ:

http://www.eng-tips.com/faqs.cfm?fid=376

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[jingansong]

I've followed the suggestion after this warning message to change the kinematic contact to the penalty contact, this warning is gone, and no error happened, but the weird mesh change thing is still there. I believe this is not correct. But I don't know what causes this.

 

[IceBreakerSours]

Some comments:

1. Uploading CAE causes troubles; always upload your input file. I couldn't see anything because I have an older CAE version.

2. I don't understand how/why you'd mesh a regular block in such an odd way. If you need to create higher density mesh closer to the rigid
3. The results are junk because your artificial strain energy (ALLAE) is more than strain energy (ALLSE) for the model; it should be very small when compared with ALLSE and other "real" energies. Along similar lines, your ETOTAL should be close to a constant; its not.

4. You don't need to create deformable elements and then a rigid body constraint. You can create a rigid body directly.

Bottomline: You need to study your model carefully.

Are you new to this forum? If so, please read these FAQ:

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083