Some problems in first attempt with Abaqus
Some problems in first attempt with Abaqus
(OP)
Hello everybody. Is my first time with Abaqus, and I´m trying to do nonlinear analysis that involves nonlinear material and model change.
I want to model 2 principal beam: one is a brigde deck (30 m. lenght), the other is a railway track (630 m.). The object is analize the track-bridge interaction. This interaction, depends of nonlinear material behavior between bridge and track in longitudinal direction (bilinear relation force-displacement).
The magnitude of the behavior, depends if the train is over the track or not (different values of the force). I modelize it with a nonlinear spring.
The principal loads are: uniform thermal load (50ºC - track; 35ºC - deck bridge), vertical uniform distributed load (80 kN/m - train weight) and horizontal uniform distributed load (20 kN/m - brake). The uniforms loads, are in function of the train position.
The order of the loads: thermal loads (without train), vertical train load and horizontal train load. So, I have to apply "model change" to change the behavior of the spring before the train loads, an after that.
The problem (finally) is that Abaqus don´t converge. I have imposed a substep size of 1E-09, but don´t solve it.
I want to model 2 principal beam: one is a brigde deck (30 m. lenght), the other is a railway track (630 m.). The object is analize the track-bridge interaction. This interaction, depends of nonlinear material behavior between bridge and track in longitudinal direction (bilinear relation force-displacement).
The magnitude of the behavior, depends if the train is over the track or not (different values of the force). I modelize it with a nonlinear spring.
The principal loads are: uniform thermal load (50ºC - track; 35ºC - deck bridge), vertical uniform distributed load (80 kN/m - train weight) and horizontal uniform distributed load (20 kN/m - brake). The uniforms loads, are in function of the train position.
The order of the loads: thermal loads (without train), vertical train load and horizontal train load. So, I have to apply "model change" to change the behavior of the spring before the train loads, an after that.
The problem (finally) is that Abaqus don´t converge. I have imposed a substep size of 1E-09, but don´t solve it.





RE: Some problems in first attempt with Abaqus
Tata
RE: Some problems in first attempt with Abaqus
Thx in advance :)
Fabio
RE: Some problems in first attempt with Abaqus
Corus, this is nonlinear because the material behavior between the track and the deck has a bilinear relation force-displacement, and depends if the train is over the rail or not.
Is something like that:
force
|
| _______________________ (with train)
| /
| /
| /
| /
| / ....................... (without train)
| / .
| / .
| /.
|/_____________________________________________ displc.
Again, thanks a lot for answering. I solved it this morning :D
RE: Some problems in first attempt with Abaqus
Tata
RE: Some problems in first attempt with Abaqus
My question is: if my first step is the boundary conditions definition and remove of certains elements ONLY, why large and strange displacements happens in several nodes?
NOTES:
---> The STEP definition:
*STEP
*STATIC
*MODEL CHANGE, TYPE=ELEMENT, REMOVE
BalastoCViaDcha02, BalastoCViaDcha03, BalastoCViaIzqda03, BalastoCViaIzqda04
*BOUNDARY
40001, 2
40081, 2
1, 2
2, 2
3, 2
4, 2
....
*END STEP
---> The STRANGE results:
***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE 30023
D.O.F. 1 RATIO = 6.06968E+09.
***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE 20017
D.O.F. 1 RATIO = 6.74370E+09.
....
Can it be, that I have overconstraints?