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Subject: UPF: Is an unsymmetric consistent tangent possible?
Author: Frank Rackwitz Frank.Rackwitz@
Date: 1999-01-13 09:50:00

Dear all,

First of all - best wishes to the new year for all subscribers of
xansys@o...
This is my problem:
I use the UPF-subroutine "userpl.f" in ANSYS 5.4 for implementing the
elasto-plastic law based on the Mohr-Coulomb yield criterion with
nonassociativ flow rule. This routine produce an unsymmetric consistent
tangent matrix.

Is it possible to solve this unsymmetric matrix with Newton-Raphson
iteration scheme ???

I read at the ANSYS Theory Reference, 4.1.7, following: "...To preserve
the symmetry of the matrix, for analyses with a nonassociative flow
rule, the matrix is evaluated using F only and again with Q only and the
two matrices averaged."

Thanks, Frank Rackwitz.

Dipl.-Ing. Frank Rackwitz
Technical University of Berlin
Institute of Geotechnical Engineering
Sekr. B7
Strasse des 17. Juni 135
D-10623 Berlin
GERMANY

EMAIL Frank.Rackwitz@T...
PHONE +49-30-314-22861
FAX +49-30-314-24492

Posts possibly associated with message #198AuthorDateScore
198UPF: Is an unsymmetric consistent tangent possible?Frank Rackwitz Frank.Rackwitz@1999/01/13 
202Re: UPF: Is an unsymmetric consistent tangent possible?Charles Rajakumar1999/01/13 
203Re: UPF: Is an unsymmetric consistent tangent possible?Grama Bhashyam1999/01/13