Learning Forum

[Costas]

Hello everyone.

Is there a possibility to include a hardening behaviour in a Mohr Coulomb model in Workbench? 

Thanks,

Costas

[John Doyle]

From Section 4.11.3 of the MAPDL Material Reference Guide (R2023-R2), with regards to Mohr-Coulomb:  "... After the material yields, the inner friction angle , cohesion , and tensile strength  harden or soften as a function of the Mohr-Coulomb and tension hardening variables,  and . "

[Costas]

Hi John,

thanks for your reply. I've read that but my problem is that I don't know how to implement the hardening parameters. Is there a way I can do this in Workbench?

[John Doyle]

We don't have a curve fitting tool in MAPDL for this model.  You might be able to do something in an excel spreadsheet, if you have test data that characterizes stress and strain beyond yield.  Excel has a solver add-on that enables you to derive parameters to minimize an expression.  If you can write an expression for the residual (error), between the trial stress (based on the formula) and the experimental (based on test data), you might be able to optimize the value for each property by solving for the minimum residual.  I have seen that done with other models.  It would be an iterative process, solving for one parameter at a time, while holding the other constant.  It is not a casual walk thru the park, but it could be done.  There are other 3rd party tools (like MCALIBRATION developed by PolymerFEM) that might also be helpful.

[Costas]

Many thanks John.

I will try.