Hyperelastic material models

[Jorgen]

There are many different hyperelastic models available, and some are better than others. What hyperelastic material do you typically use and why :?:

Are the currently available hyperelastic material models "good enough"?

[amin]

A recent study have shown that natural rubber (NR) and high damping rubber (HDR) under compression shows a high stiffness at low stretch level. At higher strain rates, and in HDR; the effect is more significant. However, the study showed that such effect can be poorly represented by the available constitutive models. This prompted to develop an improved model for representing the response of NR and HDR in compression including the high initial stiffness feature. The work also addresses the identification of viscoelastic parameters from direct experimental observation, simulation of experimental results and a comperative performanece evaluation of the available models and the proposed model.

More information is available in:

Amin, A.F.M.S., Alam, M.S. and Okui, Y. (2002). An improved hyperelasticity relation in modeling viscoelasticity response of natural and high damping rubbers in compression: experiments, parameter identification and numerical verification, Mechanics of Materials, 34, 75-95.

[Jorgen]

Sounds like a very interesting article. The high stiffness of elastomers at small strains is a problem for many hyperelastic models, so I am curious to learn more about you model.

In your summary you only mention compressive behavior. How about tension? or shear? , etc.

Is your model a hyperelastic model or a viscoelastic model :?:

[amin]

Thanks for the kind comments of Bergstrom. :!:

Infact, the model is a hyperelastic model. In the referenced paper, we verified the performance of the model in compression. However, the model is also applicable in tension and shear. The results are to appear very shortly.

In the paper, we have proposed the hyperelasticity model to represent the elastic equilibrium and instantaneous response. Then we incorporated the model in a finite deformation rate-dependent model structure. A parameter identification scheme is also proposed. The model is based on phenomenological motivation.

[tech_sks]

There are many different hyperelastic models available, and some are better than others. What hyperelastic material do you typically use and why :?:

Are the currently available hyperelastic material models "good enough"?

I have a paper on comparison of popular hyperelastic material models, effects of curve fitting and sensitivity of modeling parameters to prediction of static stiffness, presented at ECCMR 2003. How do I make it accessible to others? Also I have downloaded your thesis for studying time dependent models. We use MSC.Marc here, are there some subroutines available for your model?

thanks,
shashikant sharma

[Jorgen]

Hello Shashikant,

The subroutines (http://www.polymerfem.com/modules.php?name=User_Subroutines) that I have developed are currently available for ABAQUS and LS-DYNA. If you are interested, I would be more than happy to convert the subroutines to MSC.Marc or ANSYS. The cores of the subroutines are independent of FE package and the conversion is therefore rather straightforward.

Also, I am interested in your paper. If you email it to me I will read it with interest!

Thanks,
Jorgen

[egal]

hi,shashikant sharma,
I also want to have a copy of that paper,would you please tell me where I can download it or just forward a copy to my mailbox: wymoyx@gmail.com?

JORDAN,
would you please tell me the link to your thesis? I am really interested in the tim dependent models.

[Jorgen]

egal,

You can download my thesis from:
here (http://www.polymerfem.com/modules.php?name=Downloads&d_op=viewdownloaddetails&lid=27&ttitle=Jorgen_Bergstrom_PhD_Thesis.pdf)

Jorgen