Recently I was looking for material data for 60 Shore A rubber for a simulation. This article describes what I found and how I transformed that to material data.

There is a lot of research available about rubbers. One thing is clear from that; a standard isotropic material doesn’t describe rubber very well.

After doing some reading, I found that CalculiX supports such material using the *HYPERELASTIC keyword. After some seaching I found data for Mooney-Rivlin variant of this model. This has three parameters;

• C₁₀
• C₀₁
• D₁

In the way CalculiX defines it, D₁ would be equal to 2 ⁄ k, where k is the bulk modulus. The bulk modulus for rubbers is in the order of 1−2 GPa. That would mean a D₁ significantly smaller than CalculiX’ default value of 0.8446e-07. So we will use the latter.

In this 2018 paper I found a table of values for C₁₀ and C₀₁ for rubbers of different hardness. From that, the following material data was generated.

*MATERIAL, NAME=Mrubber_55ShoreA
*HYPERELASTIC, MOONEY-RIVLIN
** C10,C01,D1
0.382e6,0.096e6,0.8446e-07

*MATERIAL, NAME=Mrubber_58ShoreA
*HYPERELASTIC, MOONEY-RIVLIN
0.436e6,0.109e6,0.8446e-07

*MATERIAL, NAME=Mrubber_60ShoreA
*HYPERELASTIC, MOONEY-RIVLIN
0.474e6,0.118e6,0.8446e-07

*MATERIAL, NAME=Mrubber_65ShoreA
*HYPERELASTIC, MOONEY-RIVLIN
0.586e6,0.147e6,0.8446e-07

*MATERIAL, NAME=Mrubber_70ShoreA
*HYPERELASTIC, MOONEY-RIVLIN
0.738e6,0.184e6,0.8446e-07

As of this date I have not been able to properly verify these by experiment, but at least for 60 Shore A rubber calculations using these values converge nicely. And they seem to produce a realistic deformation response.