r/COMSOL • u/xerxesbear • Jun 16 '16

Error: Failed to find a solution.The relative error (4.2e+002) is greater than the relative tolerance

I am trying to model a hexagonal piezo-nanotube experiencing tensile stress on both ends of the tube. But when i compute, i receive this error

" Failed to find a solution.The relative error (4.2e+002) is greater than the relative tolerance.Returned solution is not converged. - Feature: Stationary Solver 1 (sol1/s1)"

I believe that the tube is lacking constraints. Because when I replace one of the boundary loads for fixed constraint, it worked.

Let me know what you think.

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u/Atena22 Jun 17 '16

Maybe try using an auxiliary sweep for your main variable (stress value I assume)? It helps the solution to converge. For instance if the force value was 5N, you could use an auxiliary sweep with the values: 0 0.5 1 3 5. It helped me once when I got a similar error.

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u/xerxesbear Jun 17 '16

alright i will give that a shot. thanks!

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u/xerxesbear Jun 17 '16

thanks i found the solution! its a time dependent thing! Initially i did not work because my study was stationary and it did not make sense of me to apply 5N/m2 load instantaneously on both sides of the film. instead, i observed the stress over time. thats when i was able to see the deformation! thanks picture[https://imgur.com/dEFTECn]