USDFLD: Switch between FIELD(1) and FIELD(2)

[blacky130787]

Hey guys

My Name is Dominik and I´m new here. I read a lot of comments and threads in his forum and I like it a lot, you do great help!!!

Here is my problem: I´m doing some simulations with POROUS METAL PLASTICITY. For that i´m using a USDFLD-Subroutine because I want to define variable Tvergaard-parameters (q1,q2,q3) dependent on the eqivalent plastic strain PEEQ. I started with an 1-Element-Test to verify my simulation.

Here`s the Input-file:

http://files.engineering.com/getfil...-7490d98855da&file=X_4_3_SWITCH_X_GT_2neg.inp

and the Subroutine:

http://files.engineering.com/getfil...9335-3af65e9e5ad0&file=DEVSTR_PEEQ_SWITCH.for

By the element load I calculate the triaxiality (X=Hydrostatic pressure/equivalent stress) and tell the subroutine to use either FIELD(1) for X > -2 or FIELD(2) for X <= -2. For control I write the triaxiality in the log-file. With the execption of the first time increment (i think the triaxiality isn´t defined at this time -> X = 0/0) the triaxiality is almost exact -1.33. But when I compare the results ( Compaction(1-VVF) vs PEEQ ) with the results of a calculation using only FIELD(1), they are incorrect. So I think ABAQUS doesn´t follow the condition in the subroutine.

Does anyone of you got some advise to my me solving this problem? Because in future I have to do simulations with arbitrary triaxialities and i have to find a way to handle this.

THANK A LOT FOR YOUR HELP !!!

best regards,
Dominik

 

[blacky130787]

By comapring the results I can determine that ABAQUS only use FIELD(2)({q1,q2,q3} = {1.5,1,2.25}) for his simulation... but it has to use FIELD(1) because of the existing triaxiality -1.33

 

[blacky130787]

edit:

I think I solved my problem with the simulations. The key was to define field(1) as PEEQ and field(2) as TRIAXIALITY... now I can clearly assign the field variables to their coefficients q1,q2 and q3.

The problem was that I was unkown about the fact that the table of field(1) or field(2) don´t habe to be in an ascending order. The important fact is that the row of the table has to be unique