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Failed to find a solution
Posted 6 févr. 2010, 01:51 UTC−5 1 Reply
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I am designing a microactuator in comsol multiphysics which is basically a cantilever consisting of three layers. Top layer is of 1 micrometer thick titanium layer, middle one is 2 micrometer thick silicon dioxide layer and bottom layer is of 3 micrometer thick polysilicon layer. When a voltage is applied across titanium layer, heat is produced because of joule heating effect and temperature of the cantilever rises. As different layers have different thermal expansion co-efficient, there is a deflection at the tip of free end. I am getting some deflection when applied voltage is less than 1.2 volt. But when is more than 1.2 volt, it doesn't yield any result. I dont under stand what is happening. I am doing it in 3D taking fine mesh from free mesh parameters.
All layers having rectangular cross-section and one end of the cantilever is fixed
Length and width of the cantilever are 200 micrometer and 20 micrometer respectively
The problem is basically consisting of- structural, heat transfer by conduction and conductive media dc
when I click equal sign on the menu bar to solve my problem, I get some messages on the log page
warning: ill conditioned preconditioner. Increase factor in the error estimate.....
Error: Failed to find a solution mamimum number of Newton iteration has reached, the solution has not converged, relative residual is 1000 times more than relative tolerance etc.
please give me some suggestion as quickly as possible
All layers having rectangular cross-section and one end of the cantilever is fixed
Length and width of the cantilever are 200 micrometer and 20 micrometer respectively
The problem is basically consisting of- structural, heat transfer by conduction and conductive media dc
when I click equal sign on the menu bar to solve my problem, I get some messages on the log page
warning: ill conditioned preconditioner. Increase factor in the error estimate.....
Error: Failed to find a solution mamimum number of Newton iteration has reached, the solution has not converged, relative residual is 1000 times more than relative tolerance etc.
please give me some suggestion as quickly as possible
1 Reply Last Post 24 févr. 2010, 11:21 UTC−5
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Posted:
1 decade ago
Hi,
since you're using large deformation regime, initial condition is important. If you step directly to 1.2V, the initial condition may be not good for Newton to converge.
Try to increase your voltage in steps by selecting 'parametric' from solver settings.
Peter
since you're using large deformation regime, initial condition is important. If you step directly to 1.2V, the initial condition may be not good for Newton to converge.
Try to increase your voltage in steps by selecting 'parametric' from solver settings.
Peter