Is the plastic potential associated in Inventor Nastran?

[Q_Rensen]

Hello,

When performing a nonlinear static analysis, under material data, one can specify the Yield Function (F) and corresponding Yield Criterion (Von Mises, Tresca, etc.). For example, for Von Mises Yield Criterion, this yield function becomes:

F = σvm -  σys

with σvm and σys the Von Mises and yield stress, respectively.

I pressume that Inventor Nastran uses a plastic potential (g) to calculate the plastic strains:

where ε^p is the plastic strain and g the plastic potential.

This 'flow rule' is called associated when g=F. 

Normative rules require me to apply an associated flow rule. Does Inventor Nastran use an  associated  flow rule?

More specifically, these normative rules require me to use the Tresca yield criterion with associated flow rule. Currently, I cannot confirm that this is the case in Inventor Nastran since the implementation is not transparent.

(I am also familiar with methods that use the Tresca yield criterion but with Von Mises stress as plastic potential, i.e. nonassociated, which is not allowed for our application).

Hopefully, someone here can elaborate on the implementation of plasticity in Inventor Nastran.

Big thanks in advance!

[nam_ho_kim · Accepted solution]

Yes, Inventor Nastran uses the associated plasticity where the yield function is used for the plastic potential. This is the same for all types of plasticity models, including von Mises, Tresca, Mohr-Coulomb, and Drucker-Prager models.

[Q_Rensen]

Thank you nam_ho_kim!

This was exactly the answer I was looking for and I am glad to hear that the potential is indeed associated.