Arruda-Boyce & Neo Hookean

[Flix]

Hi everyone,

Is this normal that I get the same deformation values for two simulations (rubber) made with the Neo Hookean and Arruda-Boyce models?

Thanks for your help!

flix

[Jorgen]

The neo-hookean (NH) and Arruda-Boyce eight-chain (EC) model will give the same results if the strains are "small".

- Jorgen

[Flix]

Thank you for your answer.

I would like to know a little more about what "small" means in que cases of hyperelastic material.

1. What are the range of strain that we can qualify of "small"? Is there any specific answer for that?

Now I am working with a strain around 0,4 (uniaxial) ... I imagine this is small compared to some hyperelastic material that can reach something like 800% stretch. I tried almost every fonctions available on Abaqus and I noticed that for this strain, the NH and AB functions get the worst results and they have something like 18% error.

2. Do you think this is acceptable to explain this error by the fact the material gets stiffer as it stretches? Or should I normaly get better results with these models?


flix

[Jorgen]

(1) When talking about the NH and the AB model, "small strain" is related to the "locking stretch" parameter. If the applied strain is much smaller than the "locking strain" then the two models will give the same results.

(2) I don't think that there is a generic answer to that question. Typically the AB model relatively well for large strains and multiaxial loading.

- Jorgen