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ABAQUS Explicit - defining boundary conditions and imposed displacement on rigid bodies
Hello there,
I am currently trying to model a cold-formed steel beam experiment, where load is applied through displacement control. I thought using ABAQUS/Explicit and perform a quasi-static analysis would be a good idea.
However, I have found an error I have not yet been able to overcome, and the results are not as I expected.
Here's the warning message:
WARNING: BOUNDARY CONDITIONS ON RIGID ELEMENT NODES SERVE ONLY TO DEFINE
SYMMETRY FOR CONTACT SURFACES (NODE 25 INSTANCE LOADBLOCK). THE
REFERENCE NODE SHOULD BE USED TO CONSTRAIN RIGID BODIES.
... and some of the code lines that are of interest here:
*Rigid Body, Ref Node=SupportBlock.SupportBlock-RefPt, Elset=SupportBlock.SUPPORTBLOCKELEMENTS
**
*Rigid Body, ref node=LoadBlock.LoadBlock-RefPt, Elset=LoadBlock.LOADBLOCKELEMENTS
*Nset, Nset=SupportBlock_RP, Instance=SupportBlock
25,
*Nset, Nset=LoadBlock_RP, Instance=LoadBlock
25,
**
*Boundary
SupportBlock_RP, 1, 1
SupportBlock_RP, 2, 2
SupportBlock_RP, 3, 3
SupportBlock_RP, 4, 4
SupportBlock_RP, 5, 5
SupportBlock_RP, 6, 6
*Step, name="NonLinearAnalysis"
*Dynamic, Explicit
, 0.1
*Bulk Viscosity
0.06, 1.2
**
** Displacement Application
**
*Boundary, Amplitude=LoadAmplitude
LoadBlock_RP, 1, 1
LoadBlock_RP, 2, 2, -30
LoadBlock_RP, 3, 3
LoadBlock_RP, 4, 4
LoadBlock_RP, 5, 5
LoadBlock_RP, 6, 6
I thank you in advance for any help or further input on this matter.
Best regards,
PN
You mentioned an error, and
You mentioned an error, and you only showed a warning. Is Abaqus/Explicit able to run, or does it exit? If the latter, what error is reported.
The warning you are seeing is because you have boundary conditions applied to nodes on a rigid body. Rigid bodies only have 6 DOF for the whole part, and those are defined on a reference point. So no nodes on a rigid body should have a *Boundary card applied to it, except on the reference point node specified on your *Rigid Body card.
I don't know that this issue would give you poor results, since Abaqus would probably just ignore the BCs applied to nodes other than the reference point, but give it a shot and see if it fixes your issue.
My Company - Red Cedar Technology
It is in fact a warning and
It is in fact a warning and Abaqus/Explicit is able to run the entire analysis.
However, the warning is still a bit weird, since I have clearly defined the boundary conditions on the reference node, which of course does belong to the rigid body. Nevertheless, my latest results have improved and seem much closer to what I expected, which makes me think that this issue probably isn't causing much trouble on the analysis or the final results.
Anyway, thank you very much for your input.