Need advice on rubber FEA

[RoyNeo]

Hi All

I have been using abaqus to do simulation on rectangle rubber block compression till buckling(high deformation) and are having some difference in result.

1)by using default Poisson ratio in abaqus(0.475),
for a 3D simulation result seens OK but when done in 2D, the rubber will crumble(folding over each other) together at about 60~70% of the simulation.

2)by setting Poisson ratio to 0.495,
for 3D simulation result are highly distorted element and simulation stop due to this error,but in 2D result seens OK.

I and now confuse to which reuslt is correct.
There seen to be two factor now,
2D or 3D and Poisson ratio.
Which setting is the right setting to use?

Hope that someone here can advice me.
Thanks.
Roy

 

[GBor]

Is the application appropriate for 2-D? What material model are you using: Hyperelastic, Ogden, etc.? What material properties other than Poissons?

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
Magnitude The Finite Element Analysis Magazine for the Engineering Community

 

[RoyNeo]

Hi GBor

It should be appropriate for 2D.
As what i understand, result for simulation done in 2D will be for per unit. So what i have done is to use the same cross-section for both the 2D and 3D. The 3D is also set to 1m lenght(as per unit in 2D), which mean the result should be or close to be the same for both simulation.

The simulation is done with setting hyperelastic, Mooney-Rivlin, with only uniaxial test data input, density 1000.
The only properties i change is the Poisson ratio.

 

[GBor]

How different are the results between the 3-D with the Poisson's of 0.475 and the 2-D with Poisson's of 0.495? They shouldn't be too far off.

As simple as this model is, if you would like to provide some details (dimensions of the block, Mooney-Rivlin constants, load, boundary conditions), I'll run it in a couple of other other packages and see what happens.

 

[RoyNeo]

The result of the two may be some diff but the fold of the simulated rubber still look the same so it still OK.

So what i want to find out is the use of diff Poisson's on the simulation have on 2D & 3D. What are the best/right Poisson's to use for 2D & 3D simulation.

If you would like to try, you may use bottom/top 60mm, hight 250mm, with a length of 1000mm.
(B.C.)Bottom with all dof fixed.
(Load)Top move down (with all other dof fixed)by 60%(150mm)
(Material)Sorry that i can't give the full detail, but you may use rubber that is about Hardness 60.