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Solid bodies (Mooney-Rivlin Rubber) are failing.  

 

PeterR
(@peterr)
New Member
Joined: 1 month ago
Posts: 2
September 11, 2020 3:20 pm  

Hi,
 
I am trying to setup a test rig, for impact testing of wheels. 
The construction has 4 dampeners made out of Shore 50 rubber. I found the Mooney-Rivlin constants in [MPa] 
I am working in the [kg, mm, ms, kN, GPa, kN-mm] unit system. So I have conversed the constants to [GPa]

It seems to fail due to too much compression of the elements, I think. Then at one point it collapses. 
What is wrong? Element sizing? Fixture issue? Or maybe the C10, C01 constants are wrong? 

First I thought the contact constraints between different bodies were the issue. So I have tried different surface constraints of the Dampener top and bottom surface, but that did not seems to help (automatic surface to surface, with and without friction, Tied nodes constaint). Now I am thinking the issue is within the material setup or mesh / mesh quality.

Who can have a look?

Thanks


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Negative Volume
(@negativevolume)
Senior Member Admin
Joined: 2 years ago
Posts: 326
September 15, 2020 1:49 pm  

Hi @peterr

It can be a multitude of issues. Does it seem like the model works for a little while, then fails? Or is it just really unstable from the start? 

Also, if you want to test the material without the contact, you can always just apply a displacement to a node set using *Boundary_prescribed_motion which will show if there is any stability within the material model itself. 


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PeterR
(@peterr)
New Member
Joined: 1 month ago
Posts: 2
September 21, 2020 11:19 am  

@negativevolume

Thank you for your time and answer.
It seems stable at the start, the dampeners start to compress and bulge outwards. 
However after too much compression it seems that cells are colliding and collapsing.

I will check the material using a boundary prescribed motion. Hopefully this will help.

Thank again.

Cheers,
Peter


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Negative Volume
(@negativevolume)
Senior Member Admin
Joined: 2 years ago
Posts: 326
September 24, 2020 7:35 pm  

@peterr what type of material is the part that is collapsing? I know some tricks that can help prevent elements from collapsing for certain material models. 


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