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COMSOL example model results do not match with Mathematical Model
Posted 12 juin 2011, 01:35 UTC−4 2 Replies
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Hi! I started to look into freq response analysis of a cantilever beam using COMSOL. Luckily COMSOL already has an example model "Model Library>> Structural mechanics module>>Dynamics and Vibrations>>rotating blade". While not changing anything in the model and with Omega=0 and Cloris =0, I get the following results
Resonance Freq1 = 84.36
Resonance Freq2 =528.84
Resonance Freq3 =949.31
Resonance Freq4 =1316.00
Resonance Freq5 =1481.41
Resonance Freq6 =2882.00
But Euler beam theory (options>>constants) gives me the following
Resonance Freq1 = 84.36
Resonance Freq2 =528.66
Resonance Freq3 =1862.89
Resonance Freq4 =3650.55
Resonance Freq5 =6034.61
Resonance Freq6 =9064.89
Clearly the results do not match after 2nd natural/ resonance freq. I am quite sure that COMSOL example model cannot be wrong but there is something odd. Some elaboration would be appreciated
Resonance Freq1 = 84.36
Resonance Freq2 =528.84
Resonance Freq3 =949.31
Resonance Freq4 =1316.00
Resonance Freq5 =1481.41
Resonance Freq6 =2882.00
But Euler beam theory (options>>constants) gives me the following
Resonance Freq1 = 84.36
Resonance Freq2 =528.66
Resonance Freq3 =1862.89
Resonance Freq4 =3650.55
Resonance Freq5 =6034.61
Resonance Freq6 =9064.89
Clearly the results do not match after 2nd natural/ resonance freq. I am quite sure that COMSOL example model cannot be wrong but there is something odd. Some elaboration would be appreciated
2 Replies Last Post 14 juin 2011, 08:17 UTC−4
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Posted:
1 decade ago
Hi
there are many tings that can change (but I would rather trust COMSOL for the given shape, material and loading you have defined)
Are you 100% sure you are exactly in the same dimension (2D/3D), same material, same shapes, same overall BC's ?
--
Good luck
Ivar
there are many tings that can change (but I would rather trust COMSOL for the given shape, material and loading you have defined)
Are you 100% sure you are exactly in the same dimension (2D/3D), same material, same shapes, same overall BC's ?
--
Good luck
Ivar
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Posted:
1 decade ago
You are comparing apples and oranges. The COMSOL model is a full 3D model, so it is expected that it would capture eigenfrequencies that a beam model would miss.