Modeling of a PPO+PA blend

[Harm]

Dear all,

I have to model a polymeric material called Noryl, this is a blend of PPO and PA (Nylon). I have to model compression of this material. I have got uniaxial compression data of this material and it is showing the typical s-curve (engineering strain/stress). When you display the truestress-strain though, it is no longer an s-curve but an L (because of the thickening of the sample at high strains).
The poissons ratio for this material is 0.38. The only material models I can use are Mooney-Rivlin/Ogden.

My questions are the following:

Can I use Mooney-Rivlin/Ogden if the material has a poissons ratio of 0.38?
-> These models are for incompressible to nearly incompressible materials......can 0.38 still be considered nearly incompressible?

What are the pittalls in using a nearly incompressible material model for a polymeric material which has a pr of 0.38?

Kind regards

Harm

[Jorgen]

1) Yes, you can use a Mooney-Rivlin / Ogden model for that Poisson's ratio.

I would not use a hyperelastic material model for Noryl, though. There are better choices. Can you not use an elastic-plastic material model? What FE software are you using? There are other models that are even much better than the old elastic-plastic model.

-Jorgen

[zanna85]

sorry for my English, I am an Italian graduate in mechanical engineering I did a thesis based on integrated simulation Moldflow - ABAQUS and I export the 3D model fiber filled Noryl gfn3 in ABAQUS to simulate structural. we encourage you to go down this road, in my opinion the best

[Harm]

sorry for my English, I am an Italian graduate in mechanical engineering I did a thesis based on integrated simulation Moldflow - ABAQUS and I export the 3D model fiber filled Noryl gfn3 in ABAQUS to simulate structural. we encourage you to go down this road, in my opinion the best

Dear Zanna,

thank you for your reply!

A follow up question...

What type of material model are you then using to model the fibre filled Noryl...?

Kind regards

Harm

[zanna85]

Dear Zanna,

thank you for your reply!

A follow up question...

What type of material model are you then using to model the fibre filled Noryl...?

Kind regards

Harm

their 'thermo-mechanical model in Moldflow is exported in a special file in conjunction with orthotropic with residual stress molding and the other orientation of the fibers. essentially in ABAQUS after you import a complex interface with the model property 'orthotropic for any element mesh and residual stresses.