ABAQUS and DIANA for modeling of rubber

[xaktsaroth]

Dear Dr. Bergstrom,

I am trying to compare ABAQUS model for rubber vs. DIANA model. I am tasks to check if DIANA can be used to perform the same analysis. I have the following questions.
1. DIANA offers mooney rivlin method but W=K1*(J1-3)+K2*(J2-3) where I expect that K1 = C01 and K2=C10, but according to the DIANA manual they use J instead of I, J is the modified set of deformation measures - J1=I1*I3^(-1/3) J2=I2*I3^(-1/3), J=sqrt(I3). They say that these are from the principal stretches. My question is "Does the usage of J instead of I change the solution? or is it negligible?"

2. They also have a Besseling model where a non-integer power alpha is introduced..
W=K1*(J1-3)^(alpha)+K2*(J2-3)
Do you know what values of alpha to use? or how do i determine alpha...


Thank you for your help

[Jorgen]

I have never heard of DIANA, can you give a reference or link?

(1) Your description of the Mooney-Rivlin model actually sounds exactly like the Abaqus implementation. The "strain energy density" is typically written in terms of the distortional part of I.

(2) I have never heard o fthe Besseling model, but your description make it sound like a Ogden model with one term. You can determine the required material parameters using any of your favorite calibration tools, such as my Matlab toolbox (http://polymerfem.com/index.php?pageid=umats), or Abaqus, etc.

[xaktsaroth]

http://www.tnodiana.com/

This is the website for the DIANA- it is a FEM software developed Delft.
Thanks for the information. I will continue reading and will try to ask questions again as I understand more on the topic. thanks again