Elasto-plastic constitutive law for shell 2d

[AntoMarinelli]

Dear STKO team,
for my master thesis I have to model 3 RC beams in order to evaluate the ultimate shear strength: the beams are modelled with a shell 2d that follows an elasto-plastic constitutive law and the rebars with truss elements. I was thinking about using DemageTC3D to simulate the elasto-plastic behaviour for the shall but my supervisors don't agree with this. So my question is about the possibility of using other material properties to represent the elasto-plastic. I was using the plane stress-strain relationship but it doesn't work.

Thanks in advance.
Best regards

[marafini.f]

Dear AntoMarinelli,

could you provide a drawing of the constitutive behaviour you want to model?
What do you mean by elasto-plastic?

Thank you

Francesca

[AntoMarinelli]

Dear Francesca,
I provide you the reference stress-strain constitutive law that I have to implement.

Thank you

Antonella

[marafini.f]

Dear Antonella,

you can obtain the constitutive behaviour you want with DamageTC3D if you assign a very high value in terms of fracture energy, set to 0 the plasticity and set the points of your curve accordingly.
In this picture an example with the result in the tester:

Immagine 2021-08-26 151836.png (80.95 KiB) Viewed 2870 times

Of course this references the following yield surface.

Immagine 2021-08-26 152113.png (70.55 KiB) Viewed 2870 times

See also the reference
https://www.researchgate.net/publicatio ... hear_walls

If you want to use a different yield surface, than DamageTC3D is not the right material no.

Best,
Francesca

[AntoMarinelli]

Dear Francesca,

yes, I know that I can simulate in this way but my supervisor don't want to use the fracture energy parameters so I'm wondering to find another way to model it. What could be?

Thanks in advance
Best regards
Antonella

[marafini.f]

You can try using the nDMaterial DruckerPrager, that should be able to represent what you want. It's a bit of a pain to calibrate though

[AntoMarinelli]

Ok thanks, I have already tried to use it and it is really hard to calibrate. Although, is it possible to use the PlaneStressUserMaterial for my purpose?

Antonella

[marafini.f]

Dear Antonella,

you can use PlaneStressUserMaterial, we have never used it and the documentation is quite bare. You should look in the literature of the researcher that implemented it.

Anyway it's a material that simulates the same behaviour we try to capture with DamageTC3D. Maybe you won't have to input fracture energy parameters but there will be something similar.
In the end, in the example, I posted before are not calculating those parameters, but assigning an arbitrarily large value.

Hope this helps,

Eenjoy your modelling

Francesca