Learning Forum

[MickMack]

Hi Folks,

I am trying to develop a microplane model and i am following Techno Example 54 and the youtube tutorial in the link below below; https://www.youtube.com/watch?v=JXbZnhGZliY&t=931s

I am getting the following warning; "Drucker-Prager cap plasticity integration algorithm did not converge  for element 2644 and material 1." and i would appreciate some helpin resolving this.

I have included therelevant information below.

Thanks,

Michael

[Manish Dubey]

Hi It appears from the warning message that material model is unstable. There might be several reasons for this. You need to first verify if the model converges simply with elastic definition, then try with bilinear isotropic hardening (plasticity). Next check the ÔÇ£ Auto Time SteppingÔÇ£to ON and reduce the minimum, maximum and initial time step to be sufficient small. Also check if you improve the mesh quality for the element regions mentioned in the warning message.
There is another plasticity model can be used namely Extended Drucker Prager (EDP) which addresses some basic issues of Drucker Prager model such as:
ÔÇó Only perfectly plastic model can be used with Drucker Prager.
ÔÇó Presence of sharp vertex which can result in discontinuous yield and plastic potential function resulting in convergence issues.
For EDP model the yield surface can be changed with progressive yielding and thus the sharp cone vertex be avoid. Also user can define bilinear, multilinear or nonlinear isotropic hardening with this model.
Thanks
Manish