[CIG-SHORT] plastic deformation

[Birendra jha]

Hi developers/users,

I am trying to understand Sec 5.4.2.1 Drucker-Prager Elastoplastic With No Hardening (Perfectly Plastic). Can you please point me to a paper/document which describes this formulation? For example,

1. What is the basis of Eq.(5.104), first equality? Can we write this for general loading?

2. What is the meaning of "taking the scalar product of both sides", above Eq.(5.109). I can derive lambda by multiplying Eq.(5.100) on both sides by df/dsigma : C^E. But this lamda does not quite look like (5.109) because of (5.104). also, I would like to understand d in Eq(5.110).

3. I am not able to derive the term in the bracket in Eq.(113). How does cohesion enter here?

4. Eq.(5.117): what is the basis of this split? Is it always valid?

I'd just like to understand the formulation.

Thanks for any help
Birendra

--------------------------------------------
On Thu, 10/2/14, Brad Aagaard <baagaard at usgs.gov> wrote:

 Subject: Re: [CIG-SHORT] plastic deformation
 To: cig-short at geodynamics.org
 Date: Thursday, October 2, 2014, 10:50 AM
 
 Birendra,
 
 It would help to know what you
 have tried to resolve this problem? Have 
 you checked the scales used in the
 nondimensionalization? Have you 
 verified
 convergence for the same problem with a linear elastic 
 material? Does a linear elastic material
 converge in one nonlinear solve 
 iteration?
 What else have you tried?
 
 Regards,
 Brad
 
 
 On 10/2/14, 6:39 AM,
 Birendra jha wrote:
 > Hi
 >
 > I am trying to run a
 plastic deformation case with the DruckerPrager3D material.
 The nonlinear solver does not converge. Attached are my
 files, which run.
 >
 >
 It's a very small setup: 10x1x1 column, loaded at one
 end with a cyclic load that leads to compression and tension
 in the column in a sinusoidal manner.
 > I
 want to compare the plastic strain output with my analytical
 solution.
 >
 > Can
 someone please take a look and help me with the convergence
 issue?
 >
 > Thanks
 > Birendra
 >
 >
 >
 >
 _______________________________________________
 > CIG-SHORT mailing list
 > CIG-SHORT at geodynamics.org
 > http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-short
 >
 
 _______________________________________________
 CIG-SHORT mailing list
 CIG-SHORT at geodynamics.org
 http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-short