about plastic results and definition

[Anonymous]

Hi,

I would like to know if someone here does know the exact defintions of what Algor provides as plasticity results

Equivalent stress : i understand this an (equivalent) stress measure.
The thing is that on a given model, this value very far from the von mises value (1 to 10) - so my question is

     - is this equivalent stress (under plasticity menu) the true stress state (from the elastop plastic curve)

     - and then is the von mises value given, is the stress computed only in the elastic state (as if the material would have been elastic and not plastic)

Also about plastic strain : this value represents the plastic strain or the total one ...? (in major cases, the plastic strain is very low compared to the elastic one but in my case here i have a value of 1.27 (for a elastic strain of 2.5%) that seems very very strange...)

Thanks for your clarifications.

[S.LI]

For Updated Lagrangian, equivalent stress should equal to von Mises in Algor; for nonlinear material only, these two should be very close to each other; but for Total Lagrangian, these two could be very different.

The reason is von Mises stress output is always based on Cauchy (true stress), but equivalent stress in Algor is based on PK2 stress for Total Lagrangian and Cauchy stress for Updated Lagrangian.

About the elastic-plastic strain, before material yields, there is no plastic strain. But, after yielding, plastic strain dominates the whole deformation.

[Anonymous]

Thanks for this,

In my model, i have elastoplastic material and also large displacements.

When i define updated lagrangian, the effective and von mises are close but for total lagrangian, it is not at all (also the distribution is not the same).

So this lead me to think that for von mises, i thought the stifness computed was the first (so elastic) and that was why the stress was very high, not like the effective.

So still need clarification to be sure.

Regards