Learning Forum

[moritz.mantel]

Hello everyone,

At the Moment i´m trying to build a material model for a polymer. I got tensile test data, and already figured the "true stress-strain-curve" out that i want to use.

In the two attached pictures you can see the curve. Necking started at about epsilon = 0,05 mm/mm.

Now I am really wondering how to correctly implement the data in the Ansys Engineering Data.

Right now my theory is to load the excel data until the necking point into the workbench with the uniaxial test data tool. Then i would try to get a good approximation via the hyperelastic curve-fitting tool. Afterwards i would define a yield point, and then describe the plasticity as a multinear or bilinear isotropic hardening.

(I already tried to do so but i wasn´t able to produce satisfying results...)

So my question, is this the right way, or should i change fundamental steps in my approximation?

And if this is the right way, which hyperelastic model would you recommend to describe a stress-strain curve like mine?

I´m thankful for every help,

Regards

[1shan]

Though ANSYS allows combining hyperelasticity and plasticity models, I am not sure whether it is recommended to do so ( I'll try gathering more info about this). The reason being hyperplastic material models assume that there is no plastic deformation and are meant to model only nonlinear elastic deformation. Could you give more info about the case setup and why you feel the results are not acceptable? You may want to use just the plasticity model, with the initial response as linear elastic and check if that gives you the desired result.
Regards Ishan.

[moritz.mantel]

Hello Ishan thanks for your answer. I now went with multilinear plasticity in combination with linear elasticity. The results that I get are way closer to the stress-strain-curve from the tensile tests, but I can┬┤t produce precise solutions when it comes to cyclic loads or the difference of plastic/elastic strain, because in reality the material behaviour is mostly elastic until about 6% yield.
Is there any way to describe something like multilinear elasticity in ANSYS?
Regards