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Joule Heating - Study help
Posted 06.02.2013, 00:37 GMT-5 Heat Transfer & Phase Change, Heat Transfer, Structural Mechanics 1 Reply
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Hello all,
I am currently working on modeling the thermal stresses of a surface mounted component on a PCB. However, i am currently struggling to get the physics to work. I have followed the available online tutorials to help me out with setting the physics; however, i am getting the same error consistently:
"Failed to find a solution.
Singular matrix.
For mesh-case 0 there are 40552 void equations (empty rows in matrix) for the variable mod1.V.
at coordinates: (0.00799,0.00190047,-0.00381), (0.00799,0.00183293,-0.00381), (0.00799,0.00145389,-0.00230996), (0.00797193,0.00144694,-0.00232498), (0.00799,0.00144694,-0.00232498), ...
and similarly for the degrees of freedom (empty columns in matrix).
Returned solution is not converged."
The materials have been fully define with information found through research, and i believe i have define all the boundaries properly (i followed the instructions from the tutorials to get the physics set up).
If anyone could provide any pointers or advice as to what i am missing in the modeling, i would greatly appreciate it!
Thank you very much for your time!
Santiago
I am currently working on modeling the thermal stresses of a surface mounted component on a PCB. However, i am currently struggling to get the physics to work. I have followed the available online tutorials to help me out with setting the physics; however, i am getting the same error consistently:
"Failed to find a solution.
Singular matrix.
For mesh-case 0 there are 40552 void equations (empty rows in matrix) for the variable mod1.V.
at coordinates: (0.00799,0.00190047,-0.00381), (0.00799,0.00183293,-0.00381), (0.00799,0.00145389,-0.00230996), (0.00797193,0.00144694,-0.00232498), (0.00799,0.00144694,-0.00232498), ...
and similarly for the degrees of freedom (empty columns in matrix).
Returned solution is not converged."
The materials have been fully define with information found through research, and i believe i have define all the boundaries properly (i followed the instructions from the tutorials to get the physics set up).
If anyone could provide any pointers or advice as to what i am missing in the modeling, i would greatly appreciate it!
Thank you very much for your time!
Santiago
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1 Reply Last Post 06.02.2013, 08:18 GMT-5
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Posted:
1 decade ago
Dear Santiago,
the material Al2O3 does not have any electrical conductivity, which will give zero's on the diagonal of your matrix and cause the singularity.
This can be solved in three ways:
1. Take a very small value for its conductivity
2. decouple the physics and use electric currents in the parts without the Al203; and solid heat transfer in all. Use a heat source from the ec physics.
3. add a heat transfer in solids condition and assign it on the chip. This will remove the domain from the joule heating default condition and thus will not calculate for potential in that domain.
Note that a similar error in mechanics occurs when using a poisson's ratio of 0.5 (solve by using 0.499).
Best regards,
Frank
the material Al2O3 does not have any electrical conductivity, which will give zero's on the diagonal of your matrix and cause the singularity.
This can be solved in three ways:
1. Take a very small value for its conductivity
2. decouple the physics and use electric currents in the parts without the Al203; and solid heat transfer in all. Use a heat source from the ec physics.
3. add a heat transfer in solids condition and assign it on the chip. This will remove the domain from the joule heating default condition and thus will not calculate for potential in that domain.
Note that a similar error in mechanics occurs when using a poisson's ratio of 0.5 (solve by using 0.499).
Best regards,
Frank