DG export in ABAQUS
DG export in ABAQUS
(OP)
Thanks in advance. Has anyone had trouble exporting the deformation gradient in ABAQUS? I'm using *EL FILE with 8-node brick pore stress elements. I have a hyperelastic model, and the documentation says that model type should work, however, ABAQUS will not export DG for me.





RE: DG export in ABAQUS
...
ELSE IF (KEY.EQ.30) THEN
F(1,1)=ARRAY(3)
F(2,2)=ARRAY(4)
F(3,3)=ARRAY(5)
F(1,2)=ARRAY(6)
F(1,3)=0
F(2,3)=0
F(2,1)=0
F(3,1)=0
F(3,2)=ARRAY(7)
...
ARRAY(3) and so on were taking values of DG from the fil. Since I'm now exporting the fil with u and X does anyone have any idea what I should be putting in for the values of the ARRAY. I have no clue how the fil file is structured.
RE: DG export in ABAQUS
Section 5.1.3 of the Analysis User's Manual may be of some help in dealing with a results file (ABAQUS v6.11).
http://www.eng-tips.com/faqs.cfm?fid=376
RE: DG export in ABAQUS
RE: DG export in ABAQUS
Short answer: You can not do it the way you hope to do it.
My 2 cents:
a) You have probably thought of this but can you implement the Fung model in the UMAT? This way you will have access to DG.
b) I am not sure about this but, perhaps, you could turn the UMAT into a dummy material model in which the DDSDDE/STRESS/etc. at the end of the increment is the same as it is at the beginning of the increment. Using the dummy material model in the UMAT, extract the components of DG in to a common variable and then use these in the anisotropic hyperelastic material model.
Best.
http://www.eng-tips.com/faqs.cfm?fid=376
RE: DG export in ABAQUS
I thought of implementing Fung into a UMAT, but that is my last resort.
I figured this out though. I am NOT a Fortran guy at all, and I didn't write the original transfer subroutine. The routine just modifies values in the results of the PHE analysis for use in the XPT analysis. I've finally figured it out though. To have the subroutine pick up DG without using *EL FILE and DG you can use *NODE FILE and COORD and just use F=dx/dX. To actually modify it in the ABQMAIN subroutine I simply go from
(KEY.EQ.30)
to:
(KEY.EQ.89).
I had no idea that's what the KEY.EQ was for...it's just telling the program to find a different parameter (e.g., COORD instead of DG). The ARRAY(i) is the same, but with just a little math now. I feel really stupid for knot figuring this out sooner. Thanks for your help man!
RE: DG export in ABAQUS
By the way:
node file output request record key for COORD: 107
element file output request record key for COORD: 8
89 is for logarithmic strains.
http://www.eng-tips.com/faqs.cfm?fid=376
RE: DG export in ABAQUS