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OpenFOAM stress analysis results are showing 8-10% error with analytical solution.

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Old   September 10, 2012, 12:52
Default OpenFOAM stress analysis results are showing 8-10% error with analytical solution.
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Sangeeta
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Hello everyone,

I am running solidDisplacementFoam problem for thermal stress analysis. My solution is converged but not showing good agreement with analytical solution.

Simulation results shows 8-10% error with analytical solution. Does 8-10% error is fine for solid problems?

Has anybody an idea?

Regards,
Sangeeta
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Old   September 10, 2012, 14:32
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Philip Cardiff
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Hi Sangeeta,

I presume you are referring to the "hollow cylinder with internal temperature" case as described by Timoshenko, Theory of Elasticity.

I tried this case and I found that the errors become very small (much much less than 1%) as you refine the mesh.

I have attached an graph showing a comparison between the results from a coarse and fine mesh.

To answer your question about "is 8-10% error ok?", in general for solid mechanics, it depends on the assumptions made in the analytical solutions (and in the numerical model). But for relatively straight-forward linear elastic and thermal elastic, the results should be very close to the analytical, especially as the mesh is refined.

Hope it helps,
Philip
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Old   September 10, 2012, 15:06
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Quote:
Originally Posted by bigphil View Post
Hi Sangeeta,

I presume you are referring to the "hollow cylinder with internal temperature" case as described by Timoshenko, Theory of Elasticity.

I tried this case and I found that the errors become very small (much much less than 1%) as you refine the mesh.

I have attached an graph showing a comparison between the results from a coarse and fine mesh.

To answer your question about "is 8-10% error ok?", in general for solid mechanics, it depends on the assumptions made in the analytical solutions (and in the numerical model). But for relatively straight-forward linear elastic and thermal elastic, the results should be very close to the analytical, especially as the mesh is refined.

Hope it helps,
Philip
Hi Philip,

Thanks a lot for the reply. Actually here I am solving another problem of thermal stresses for OpenFOAM validation. This problem is given in Timoshenko (page no. 399). This is for a rectangular plate.

I am going to email this case to you.

Thanks,
Sangeeta
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