Cyclic load on POM

[Marc]

Hello,

in my thesis i have to suimulate cyclic pressure load on POM and calculate the accumulated plastic strain (in Abaqus).

How is it possible to perform this task? Do i need a material model or is it O.K. if i use viscoelastic in Abaqus?

I have creep elastic modulus test data.

Is it O.K. to calculate shear modulus by G(t)=E(t)/(2*(1+n)) an to intruduce in Abaqus because Abaqus requires Shear modulus or Volumetric modulus test data?

Which options do I need?

Thanks a lot!!:oops:

[Jorgen]

(1) Linear viscoelasticity will likely give bad predictions. If you have a budget for your project then you might consider obtaining the PolyUmod (http://usermaterial.polymerfem.com/) library which contains excellent material models for POM. If that is not an option that I suggest that you use the hyperelastic-plastic model that is in the latest version of Abaqus.

(2) Yes, you can approximate the shear modulus that way.

- Jorgen

[Marc]

Hi Joergen!

At first, I want to thank you for your competent reply!

-You suggested the hyperelastic-plastic model. Which plastic hardening you suggest me to use, isotropic, kinematic or combined? What do i have to do?

-What about two-layer plasticity?

Thanks!

Marc

[Jorgen]

The you are only interested in mononic loading, then you can use an isotropic hardning model. If you have any form of unloading, then I recommend either kinematic or combined hardening.

I have not had much luck with the two-layer plasticity model in Abaqus.

- Jorgen