Thermal Simulation Failure

[abentz64]

I have done rudimentary simulation in other categories but this is my first thermal attempt. Through multiple attempts and lots of simplification of the design, I still am unable to get the simulation to complete successfully. The simplification refuses to remove the leftover fillets and I do not have access to the original part file in order to change the design. The pre-check is green and I have checked multiple times with no interference errors. I initially thought the mesh might be too coarse and therefore used a finer mesh along with a low adaptive mesh refinement. Every attempt to solve locally or on the cloud results in an identical error of 

Error: SINGULARITY DETECTED AT GRID 52341 COMPONENT 1
Cause : A singularity has been detected in the stiffness matrix during decomposition.
Action : Investigate the degree of freedom at which the singularity occurred for a lack of
stiffness. Also, check your model for a lack of constraint. If using shell elements,
either set the K6ROT model parameter to a value between 1.0 and 100.0, or set the
SHELLRNODE model parameter to ON. If this does not solve the problem or you are unable
to locate the source of the singularity, consider setting the SOLUTIONERROR model
parameter to ON. Note that solution accuracy may be degraded with this parameter set
to ON. Check the EPSILON value in the Model Results Output or Results Summary File.
Values greater than 0.001 indicate a possible loss of accuracy.

I have been able to run a similar result with only one red cell located in the center but have not been able to run with 2 or 3 cells. 

Any help on deciphering the solution errors or how to make the design feasible?

[John_Holtz]

Hi @abentz64 

A singularity is normally caused by one of these items:

1. The parts are not connected together. Did you define contact and bond all of the parts together? (This is necessary so that the heat can conduct from one part to an adjacent part.)
2. The material properties are wrong. (Usually not a problem with heat transfer analysis since only the thermal conductivity is required, but still worth checking that all conductivities are valid.)
3. The mesh is distorted. You should generate the mesh and see if there are any obvious locations where the mesh is producing long, slender "needles". Also, I would suggest turning off "Manage > Settings > Mesh > Advanced Settings > Create Curved Mesh Elements". In other words, uncheck/untick that box.

If it still fails after checking those things, feel free to export the model ("File > Export") and attach the .f3d file so that someone can look at it.