Sequentially Coupled Analysis
Sequentially Coupled Analysis
(OP)
I am simulating a sequentially coupled thermal analysis. I am working with an assembly. I have completed a thermal analysis and then modified the input file for element type, predefined field, boundary conditions(after saving under a different name). I keep getting an error that "abaqus exited with error" with no other explanation in the log file. There is no message file generated.
Could you please look at part of the input file below and see if something is grossly wrong.
Some more info
1. I used tet mesh in thermal analysis with DC3D4 elements
2. In the following mechanical analysis I kept the same mesh and changed the element type to C3D4
3. Used .odb file for predefined field temperature data.
** INTERACTIONS
**
** Interaction: moly-part3
*Contact Pair, interaction=IntProp-1
cebaf_asm-3-1.side, molymn-1.insdang-lft
** Interaction: part1-moly
*Contact Pair, interaction=IntProp-1
molymn-1.outsdsd, cebaf_asm-1-1.side
** Interaction: part2-1
*Contact Pair, interaction=IntProp-1
cebaf_asm-1-1.outrbtm, cebaf_asm-2-1.btm
** ------------
**
**
** STEP: Step-1
**
*Step, name=Step-1
*Static
1., 1., 1e-05, 1.
**
** BOUNDARY CONDITIONS
**
** Name: BC-1 Type: Displacement/Rotation
*Boundary
_PickedSet18, 1, 1
_PickedSet18, 2, 2
_PickedSet18, 3, 3
_PickedSet18, 4, 4
_PickedSet18, 5, 5
_PickedSet18, 6, 6
**
** PREDEFINED FIELDS
**
** Name: Predefined Field-1 Type: Temperature
*Temperature, file=cebaf_01convc.odb
**
** OUTPUT REQUESTS
**
*Restart, write, frequency=0
**
** FIELD OUTPUT: F-Output-1
**
*Output, field, variable=PRESELECT
**
** HISTORY OUTPUT: H-Output-1
**
*Output, history, variable=PRESELECT
*End Step
Could you please look at part of the input file below and see if something is grossly wrong.
Some more info
1. I used tet mesh in thermal analysis with DC3D4 elements
2. In the following mechanical analysis I kept the same mesh and changed the element type to C3D4
3. Used .odb file for predefined field temperature data.
** INTERACTIONS
**
** Interaction: moly-part3
*Contact Pair, interaction=IntProp-1
cebaf_asm-3-1.side, molymn-1.insdang-lft
** Interaction: part1-moly
*Contact Pair, interaction=IntProp-1
molymn-1.outsdsd, cebaf_asm-1-1.side
** Interaction: part2-1
*Contact Pair, interaction=IntProp-1
cebaf_asm-1-1.outrbtm, cebaf_asm-2-1.btm
** ------------
**
**
** STEP: Step-1
**
*Step, name=Step-1
*Static
1., 1., 1e-05, 1.
**
** BOUNDARY CONDITIONS
**
** Name: BC-1 Type: Displacement/Rotation
*Boundary
_PickedSet18, 1, 1
_PickedSet18, 2, 2
_PickedSet18, 3, 3
_PickedSet18, 4, 4
_PickedSet18, 5, 5
_PickedSet18, 6, 6
**
** PREDEFINED FIELDS
**
** Name: Predefined Field-1 Type: Temperature
*Temperature, file=cebaf_01convc.odb
**
** OUTPUT REQUESTS
**
*Restart, write, frequency=0
**
** FIELD OUTPUT: F-Output-1
**
*Output, field, variable=PRESELECT
**
** HISTORY OUTPUT: H-Output-1
**
*Output, history, variable=PRESELECT
*End Step





RE: Sequentially Coupled Analysis
***NOTE: SEVERE CONTACT OVERCLOSURES EXIST. CONVERGENCE IS JUDGED UNLIKELY.
I think the model which is an assembly of 4 parts has issues with contact. I have defined surface-to-surface contact in thermal analysis and it seems to be going smooth and gave me good results. But when I do the subsequent structural analysis as part of the sequentially coupled analysis I get the above overclosures error.
Any ideas how to overcome this problem. Thanks
Yousuf
RE: Sequentially Coupled Analysis
Regards,
jo
RE: Sequentially Coupled Analysis
corus
RE: Sequentially Coupled Analysis
***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE CEBAF_ASM-3-1.166 D.O.F. 1 RATIO = 2.71455E+13.
I have tried a few options in the interactions but they didnt work. Please help. Thanks
RE: Sequentially Coupled Analysis
corus
RE: Sequentially Coupled Analysis
I have constrained a surface in all DOF as my boundary condition. However I did not see a blank against the 6 DOFs in which I could fill out zero to show full constraint. I have seen this earlier that gainst each DOF there is a blank box but in this case I did not see any. Would you know why this option is not available? Thanks.
RE: Sequentially Coupled Analysis
corus
RE: Sequentially Coupled Analysis
Yesterday I changed the step to initial and it worked and your message confirms it.
I continue to get negative eigen value errors. Is contact a problem even with linear tetra elements like C3D4? My model is a little complex I tried meshing with hex elements but partitioning the model was impossible. Any idea as to how to mesh such models with hex elements? I know hypermesh and other such software can mesh such models easily but I would like to know if there is a work around with in abaqus. Thanks again.
RE: Sequentially Coupled Analysis
If you still want to mesh with Abq perhaps you want to check if your geometry needs to be repaired.
hope this helps,
jo
RE: Sequentially Coupled Analysis
Thanks for your suggestion. Unfortunately I don't have access to Hypermesh so I guess I am stuck with Abaqus :(
RE: Sequentially Coupled Analysis
If it's a complex problem you have with contact then it's better to try and simplify it first and then build in the complexity later to see how far you can go. I know if you bang in plasticity with large displacemnt and contact between several objects then there's fat chance of it working straightaway.
corus