ERROR: CONTA + TARGE ELEMENTS

[richardforever]

Hello everyone!,
My main concerned is about an error that ansys give me when i try to put the boundary conditions of a thermal analysis problem.
I'm tryin to simulate a die attached to a copper area by means of a thick layer of thermal grease
I have used conta 172 +targe169 because it's a 2d model. I have introduced this:

ET,3,CONTA172
KEYOPT,3,1,2
KEYOPT,3,2,2
KEYOPT,3,4,2
KEYOPT,3,12,5
ET,4,TARGE169

R,3,,,,,,0.1 !PINBAL region is set to 0.1 cause if i let as a default(0.25) ansys gives me an error saying that in order to use penetration or a gap i have to increase this value , if not i have to decrease.
RMORE,,,,,,,
RMORE,,5,,,,, !TCC is set to 5 for the contact line

The problem comes when i am in /POST1 and everything seems fine but an error pop ups saying that:
"Smoothing on certain contact/target nodes (for example 819) may have an accuracy issue. You may switch contact and target surfaces, or split the current pair into multiple pairs, or use Gauss detection.
MPC will be built internally to handle bonded contact.
Average contact surface length 0.40984E-03
Average contact pair depth 0.22952E-03
Pinball region factor PINB 0.10000
The resulting pinball region 0.22952E-04
Default target edge extension factor TOLS 10.000
Auto offset used to close gap/penetration -0.13739E-16
Initial penetration/gap is excluded.
Bonded contact (always) is defined."


I don't understand this message cause i cannot change keyopt,3,4,2 to 3,4,0 (GAUSS) because doesn't let me use MPC (multipoint constraint) which is what i want to use.
What I have to do?. Any ideas? Thank you for the helpful responses.

 

[rickfischer51]

This isn't an error, it's just an information type warning.

Rick Fischer
Principal Engineer
Argonne National Laboratory

 

[richardforever]

Got it! Thanks!
There is a message that doesnt let me calculate the model when I change the place where the convection is applied (so it's an error of the model) and says that:

"The value of temp at node 1040 is 2.405769017E+14 is greater than the current limit of 1000000. This generally indicates rigid body motion as a result of a unconstrained model.Verify that your model is properly constrained."

"If one of more parts of the model are held together only by contact verify that the contact surfaces are closed. Also make sure that there are constraints (or friction) in the sliding direction even if no loads are applied in that direction. You can use CNCHECK command."

My opinion about where the error could be (I'm not sure) is about de definition of the SURF151 elements for convection. I want to apply convection of 51 W/m2ºC at the botton of mi model but as I have sliced the areas and they are not glued when i put this command:

LSEL,R,EXT
LSEL,R,LOC,Y,0
LSEL,R,LOC,X,0,0.0225
NSLL,,1
ESLN
N,5000,,-0.01 !This is an extra node to fix the temp at 50ºC after of this.
TYPE,2
REAL,2
ESURF,5000
ALLSEL
SAVE
FINISH

I think Ansys doesn't recognize exterior lines besides that when I put this command to verify if convection is correctly applied I realised that it doesn't exist!. Why Ansys doesn't apply convection? (I have done the same thing with all the areas glued and it does correctly)

/SOLU
/PSF,CONV,2
EPLOT