Mooney Rivlin Material Constants

[ave81]

Hi everybody,

i am new in the field of simulating elastomeres in FEM. I have found some information about how to determine/measure my invariants to fill the mooney rivlin model.

But i still dont understand where i get the C1...C11 from.

My formula:

W= C10(I1-3)+ C1(I2-3)+ C11 (I1-3)(I2-3)+ C20(I1-3)²+C30(I1-3)³

in the literature it says that i can neglect some coefficients so i get:

W= C10(I1-3)+ C1(I2-3)+ C11 (I1-3)(I2-3)

I read some threads but i couldnt find something that gives me enough information to solve the problem!

Thanks for your help!

dave

[Muzialis]

Ave81,

the constants are determined from experimental data in order to provide the best possible fit.
Ideally data should come from different tests but it might be sufficient to use data related to deformation modes you are about to simulate.

You can use built in functions (there is certainly one in Ansys, I am sure Abaqus or Marc have similar options) or you can implement your own method.
In general you would have to to:

- find the true stress as a function of the unknown constants
- convert everything to true stress and minimize the differences with the measured data

Hope this helps

ATB

Muzialis

[ave81]

Thank you for your answer Muzialis!

For me it sounds still a little abstract. Is there any paper or documentation about the analysis you where writing about? Or something like a experimental manual, how to determine those values?

Thanks a lot for any help!

Dave

[Felhos]

Hi!

Some info related to the Mooney-Rivlin material model are attached in the pdf file.

Good luck, have fun!

David Felhos

[Muzialis]

ave81,

I do not know any source on this specific matter, but I have put a sample calculation in attachment, it might help.



All he Best

Muzialis

[nandish.rv]

take two parameter mooney-rivlin model
parameters are c1 and c2, d. these can be found by using following relation
shear modulus=2(c1+c2)
d=2/k
k=bulk modulus

initially take c2 as zero and increasing the c2 values and find c1 for corresponding c2 values.


• E = 3 K (1 - 2v)
• E = 2 G (1 + v)

nandish rv
bangalore

Hi everybody,

i am new in the field of simulating elastomeres in FEM. I have found some information about how to determine/measure my invariants to fill the mooney rivlin model.

But i still dont understand where i get the C1...C11 from.

My formula:

W= C10(I1-3)+ C1(I2-3)+ C11 (I1-3)(I2-3)+ C20(I1-3)²+C30(I1-3)³

in the literature it says that i can neglect some coefficients so i get:

W= C10(I1-3)+ C1(I2-3)+ C11 (I1-3)(I2-3)

I read some threads but i couldnt find something that gives me enough information to solve the problem!

Thanks for your help!

dave

[sarturo]

Is anyone able to download the attached pdfs? All I get is a blank page when i click on the link.

[nandish.rv]

i am also getting same as you

[Crani]

They have been uploaded quite some time ago. What a pity, they are not accesible any more. Perhaps David and Muzialis could upload them again for us.

[Jorgen]

Hi Crani,

I am quite surprised that those attachments are not available anymore. Despite my best attempts they must have been lost at a previous update cycle.

-Jorgen