Hi,
I am trying to apply ASDPlastic ndmaterial into my model. I am trying to do this material with a Drucker-Prager yield surface. According to the manual, the DP yield criterion is defined as:
f(sigma) =SQRT((s-alpha).(s-alpha)) - SRT(2/3)*k*p
For alpha and k is defined in the manual as backstress and vonmisesradius.
The Drucker-Prager yield criterion is commonly is defined as:
f(sigma) = alpha*(I1) + SQRT(J2) - k .
and alpha and k is determined by the friction angle 'phi' and soil cohesion 'c' by:
alpha = [2sin(phi)]/[SQRT(3)*(3-sin(phi))]
k = [6*c*cos(phi)]/[SQRT(3)*(3-sin(phi))]
How do I define the alpha and k in the given yield criterion provided in ASDPlastic and material? Could a definition of alpha and k be defined in phi and cohesion?
RE: ASDPlastic material
Re: RE: ASDPlastic material
Hi,
Thank you for your interest. The current implementation of the DP model does not consider cohesion, so there is no direct way to "match" a cohesive DP model. We'll consider implementing cohesion terms in the near future. This family of models is still undergoing active development and should be considered at a "beta" stage. By the end of the year we plan to provide a release version with more features and examples.
What are you trying to model right now? It might be good to keep as a reference as we continue to develop.
Regards,
JAA
Thank you for your interest. The current implementation of the DP model does not consider cohesion, so there is no direct way to "match" a cohesive DP model. We'll consider implementing cohesion terms in the near future. This family of models is still undergoing active development and should be considered at a "beta" stage. By the end of the year we plan to provide a release version with more features and examples.
What are you trying to model right now? It might be good to keep as a reference as we continue to develop.
Regards,
JAA
Re: RE: ASDPlastic material
Hi,
Thank you for your reply. Your work is really helpful.
I am currently working on modelling a loaded circular rigid footing on a DP (Drucker-Prager) soil until the plastic yield stage. I would also like to extend this model to incorporate the Mohr-Coulomb (MC) soil model, as OpenSees does not include a standard MC model in its list of NDmaterials.
If I still choose to use ASDPlastic for a cohesionless soil, how can I derive the value of k in terms of the friction angle phi? I am conducting an initial gravity stage analysis to establish the initial stresses in my soil body. Does this mean that I should use an average p (mean stress) for the entire soil body to calculate the value of k?
Thank you for your reply. Your work is really helpful.
I am currently working on modelling a loaded circular rigid footing on a DP (Drucker-Prager) soil until the plastic yield stage. I would also like to extend this model to incorporate the Mohr-Coulomb (MC) soil model, as OpenSees does not include a standard MC model in its list of NDmaterials.
If I still choose to use ASDPlastic for a cohesionless soil, how can I derive the value of k in terms of the friction angle phi? I am conducting an initial gravity stage analysis to establish the initial stresses in my soil body. Does this mean that I should use an average p (mean stress) for the entire soil body to calculate the value of k?