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Convergence error

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Hello,

I am new to COMSOL and trying to figure out why I am getting a convergence error when trying to run a simple joule heating and structural deformation test. The structure contains 2 copper blocks, 200 um wide, attached by a 1 um thick solder layer. The error I'm getting is given below:

Failed to find a solution. In Solid Mechanics: The relative error (0.011) is greater than the relative tolerance. There was a warning message from the linear solver. Iterative refinement triggered. Returned solution is not converged. Not all parameter steps returned.

Some possible solutions I tried are given below: 1) Reduce the size of the mesh 2) Add heat flux to allow the heat to exit and reach a stationary result

I am conducting a stationary study as that is what is required for my research. I am attaching the file to this post as well. I am not sure if missing material properties is causing this issue as well. Any suggestions are highly appreciated.



1 Reply Last Post 2021年4月2日 GMT-4 14:40
Jeff Hiller COMSOL Employee

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Posted: 4 years ago 2021年4月2日 GMT-4 14:40
Updated: 4 years ago 2021年4月3日 GMT-4 00:01

Hello Waliul,

Your solid mechanics problem needs sufficient boundary conditions to remove all 6 rigid body motions, or else the problem does not have a unique solution. See e.g. this older thread and many more like it.

Best regards,

Jeff

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Jeff Hiller
Hello Waliul, Your solid mechanics problem needs sufficient boundary conditions to remove all 6 rigid body motions, or else the problem does not have a unique solution. See e.g. [this older thread](https://www.comsol.com/forum/thread/157462/simulating-uniaxial-tensile-test?last=2017-10-19T19:38:55Z) and many more like it. Best regards, Jeff

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