COMSOL example model results do not match with Mathematical Model

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SUMMARY

The forum discussion centers on discrepancies between frequency response results obtained from COMSOL's example model for a cantilever beam and those calculated using Euler beam theory. The COMSOL model yields resonance frequencies of 84.36, 528.84, 949.31, 1316.00, 1481.41, and 2882.00 Hz, while the Euler beam theory provides significantly different results for the higher resonance frequencies, indicating a mismatch after the second natural frequency. The discussion highlights the importance of correctly defining boundary conditions when performing modal analysis in COMSOL.

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  • Familiarity with COMSOL Multiphysics, specifically the Structural Mechanics Module
  • Understanding of modal analysis and resonance frequency concepts
  • Knowledge of Euler beam theory and its application in structural analysis
  • Experience with defining boundary conditions in finite element analysis
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  • Review COMSOL documentation on defining boundary conditions for modal analysis
  • Study the differences between COMSOL's rotating blade model and cantilever beam analysis
  • Learn about the implications of boundary conditions on resonance frequencies in finite element models
  • Explore advanced features in COMSOL for frequency response analysis
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Engineers, researchers, and students involved in structural analysis, particularly those using COMSOL for modal analysis of beams and other structures.

Oscar6330
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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
 
Physics news on Phys.org
You're wanting to solve a cantilever beam modal analysis, but used a rotating blade vibration analysis. How are the boundary conditions defined?
 

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