Comsol: Utilizing Symmetry Planes for Finer Grid

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SUMMARY

The discussion focuses on utilizing symmetry planes in COMSOL Multiphysics to reduce degrees of freedom (DoFs) for a structural model requiring a fine grid. The user successfully implemented two symmetry planes, creating a quarter model, but encountered issues with eigenfrequency calculations. While the full geometry yielded an eigenfrequency of 3.5 Hz, the quarter model with symmetry constraints produced an erroneous frequency of 1345 Hz, suggesting a misinterpretation of the symmetry boundary conditions by COMSOL. The user seeks clarification on correctly defining the model as a quarter representation.

PREREQUISITES
  • Understanding of COMSOL Multiphysics version 5.6 or later
  • Knowledge of symmetry boundary conditions in finite element analysis
  • Familiarity with structural modeling concepts, including solid and shell subdomains
  • Basic principles of eigenfrequency analysis in mechanical systems
NEXT STEPS
  • Research how to correctly implement symmetry boundary conditions in COMSOL Multiphysics
  • Explore the effects of symmetry planes on eigenfrequency calculations in structural models
  • Learn about the differences between global geometry and quarter model representations in finite element analysis
  • Investigate best practices for validating eigenfrequency results against experimental data
USEFUL FOR

Structural engineers, finite element analysts, and researchers using COMSOL Multiphysics for modeling and simulation of mechanical systems, particularly those interested in optimizing models with symmetry considerations.

lucky_1809
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Hi
I realize a model that requires a very fine grid in comsol, so i have reduced the DoFs using symmetry planes. My structural model has 2 symmetry planes, so i have built a quarter of the total model, but now I don't know the way to tell to comsol that the realized model is only a quarter of the total...help me please!
 
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what is the phisics of your subdomain? I use a symmetry boundary condition for a fluid and plane symmetry (corrisponding to the goemetry plane's symmetry) for a solid.
 
hello, forgive me for the delay in the answer but i was on holiday in cyprus, very beautiful place...My model is structural model with solid subdomain and shell subdomain, and I want to find eigenfrequencies... I tried to find eigenfrequencies in 2 ways...I realized the global geometry and after a slowly processing i found eigenfrequencies that are about the frequencies founded in experimental activity(the first f = 3.5Hz)..after i have built a quarter geometry and I put symmetry constraints like you told me, but I found very high frequencies (the first f = 1345 Hz). I supposed that comsol considers this constraints in a wrong way like an external constraint and not a symmetry plane.thank you
 
I have encountered a vertically oriented hydraulic cylinder that is designed to actuate and slice heavy cabling into sections with a blade. The cylinder is quite small (around 1.5 inches in diameter) and has an equally small stroke. The cylinder is single acting (i.e. it is pressurized from the bottom, and vented to atmosphere with a spring return, roughly 200lbs of force on the spring). The system operates at roughly 2500 psi. Interestingly, the cylinder has a pin that passes through its...

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