Abaqus/Explicit VUEL questions

[macmallo]

Hello,

I am currently implementing an Abaqus VUEL for a coupled displacement-nonlocal damage simulation.
So in principle I have an additional coupled field, which describes the "nonlocal" material damage.
My VUEL is working so far, but certain aspects of the VUEL interface and simulations involving VUELs are still unclear to me.

1) I am using the displacment dofs (1-3) and the temperature dof (11).
The temperature dof is abused to simulate the field of nonlocal material damage.
This seems to work both
in

*DYNAMIC, EXPLICIT

and

*DYNAMIC TEMPERATURE-DISPLACEMENT, EXPLICIT

simulations. For both step types, dof 11 is updated. This is also inline with the documentation. So what is the difference between those step types for a VUEL?
As far as I can tell, in the latter type the simulation terminates if the "temperature" rate is excessive -- which is annoying. I couldn't find any option to disable this termination.

2) For Abaqus/Standard UELs, Element SDVs can be exported to the .fil file. This seems to be impossible for VUELs. How can I actually export VUEL SDVs to any output file?

***WARNING: Element output to the results file is not supported for user                                                                                                     
            elements.

3) Kinetic energy: For simulations involving VUELs, the kinetic energy seems to be completely wrong. For me, it is just oscillating towards 0 with a small amplitude (~1e-2).
According to the documentation (2024), I cannot compute and update the kinetic energy for a VUEL.
So how is it actually computed?

Sample output:
              STEP     TOTAL      WALL      STABLE    CRITICAL    KINETIC      TOTAL                                                                                         
INCREMENT     TIME      TIME      TIME   INCREMENT     ELEMENT     ENERGY     ENERGY                                                                                         
        0  0.000E+00 0.000E+00  00:00:00 8.897E-06         541  1.500E-05  1.500E-05                                                                                         
Results number 0 at increment zero.                                                                                                                                         
Output Field Frame Number     0, of    100, at step time 0.000E+00                                                                                                           
     1124  1.000E-02 1.000E-02  00:00:00 8.897E-06         541  1.193E-01 -6.728E-02                                                                                         
Results Number  1 at step time 1.00006E-02                                                                                                                                   
Output Field Frame Number     1, of    100, at step time 1.000E-02                                                                                                           
     2248  2.000E-02 2.000E-02  00:00:01 8.897E-06         541  2.978E-02 -2.554E-01                                                                                         
Results Number  2 at step time 2.00011E-02                                                                                                                                   
Output Field Frame Number     2, of    100, at step time 2.000E-02                                                                                                           
     3372  3.000E-02 3.000E-02  00:00:02 8.897E-06         541  6.613E-02 -5.715E-01                                                                                         
Results Number  3 at step time 3.00017E-02                                                                                                                                   
Output Field Frame Number     3, of    100, at step time 3.000E-02                                                                                                           
     4496  4.000E-02 4.000E-02  00:00:02 8.897E-06         541  2.451E-02 -1.004E+00                                                                                         
Results Number  4 at step time 4.00022E-02                                                                                                                                   
Output Field Frame Number     4, of    100, at step time 4.000E-02                                                                                                           
     5620  5.000E-02 5.000E-02  00:00:03 8.897E-06         541  4.797E-02 -1.547E+00                                                                                         
Results Number  5 at step time 5.00028E-02                                                                                                                                   
Output Field Frame Number     5, of    100, at step time 5.000E-02                                                                                                           
     6744  6.000E-02 6.000E-02  00:00:04 8.897E-06         541  7.959E-02 -2.192E+00

Any help is appreciated, thank you very much !

 

[FEA way]

So what is the difference between those step types for a VUEL?

The latter includes full (two-way) coupling between thermal and mechanical DOFs.

How can I actually export VUEL SDVs to any output file?

It seems that you have to print them directly from the subroutine.

So how is it actually computed?

From what I know, kinetic energy is not available in VUEL, you can't modify/calculate it but this limitation doesn't affect the results and Abaqus/Explicit should correctly calculate kinetic energy for user elements.

 

[macmallo]

Thank you very much.
It works really well, but I think compared to UEL the interface is not as mature.
For instance, parameter dMassScale seems to be not working; it is always zero.
.fil file output is totally buggy. For instance, element sets are completely wrong exported when using parallelization (at least with mp_mode=threads).

Nevertheless, I was able to implement what I wanted.
Figure shows a pull out test of a headed stud embedded in concrete. Colors indicate fracture using the temperature field.
Contour plot generated from the .fil file using Paraview.

For anybody interested, please feel free to contact me if you need more information.