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-   -   [ANSYS Meshing] Steady-State Thermal PCB Model Meshing and Unknown Errors (https://www.cfd-online.com/Forums/ansys-meshing/192740-steady-state-thermal-pcb-model-meshing-unknown-errors.html)

GWCooke22 September 9, 2017 20:07

Steady-State Thermal PCB Model Meshing and Unknown Errors
 
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I'm doing a thermal simulation of a PCB model which contains a total of 1801 bodies consisting of 16 layers of copper traces encased in plastic (pictures attached).

I'm getting some errors and am hoping someone can help. Here is my exact workflow so far:

Step 1) Import geometry as a STEP file (takes an hour)
Step 2) Apply Heat Flow to various faces
Step 3) Change materials from Structural Steel to Copper and Plastic
Step 4) Add Temperature, Heat Flux, and Directional Heat Flux to Solution
Step 5) Solve --> ERROR 1: "At least one contact pair has no elements in it. This may be due to mesh defeaturing. Please modify defeaturing settings which are accessible on the Mesh object."
Step 6) Click Go To which highlighted Contact Area 7176
Step 7) Suppress Contact Area
Step 8) Solve --> ERROR 2: "An unknown error occurred during solution. Check the Solver Output on the Solution Information object for possible causes."

There was only a single line in Solution Information which did not add any new information.

Because I've never had to edit mesh properties and such in the past, I'm not confident about the consequences of what I did in Step 7 above, so I just reloaded a saved version that left off at Step 4 above.

I would truly appreciate any help on this. If possible, I was hoping maybe I could even just send someone the file and they could fix it.

Thanks,
Gary

GWCooke22 September 11, 2017 11:08

It turns out I was able to get it working.

There were really just two problems:

1) There was one extra body that shouldn't have been there anyway that was causing the contact pair error, so I deleted that body.

2) I hadn't specified any convection, radiation, or temperature values, so I specified the proper convection values.

I also took the following further precautions just in case:

3) I opened the 3D model in SpaceClaim and did Repair > Stitch, Gaps, Missing Faces, Split Edges, Inexact Edges, and Extra Edges. It didn't find any problems for Gaps, Missing Faces, or Inexact Edges, and there was only one Extra Edge that it couldn't repair (located at a place that touched the extra body mentioned in (1)), which turned out to be inconsequential.

4) I deleted a few more small bodies that didn't quite come out right.

I am now generating results, which right now are not the ones I want, but there are a few ways in which I can make the model more accurate, which I'm trying out now.


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