Learning Forum

[Mahmoud Darwish]

During a recent modal analysis performed on a simple beam, to determine its natural frequency sqrt(k/m​).

The beam in question has a radius (R) of 12.5 mm and a length (L) of 500 mm. Its calculated mass is approximately 1.9266 kg.

During the analysis, I observed significant differences in the natural frequency results when the beam was modeled using different element types compared to a direct theoretical calculation:

• Direct Calculation: The natural frequency was calculated to be approximately 139 Hz.
  Beam element :

• 

• Solid parts
• Can anyone explain why?

[ErKo]

Hi

See this course where the same verification is done.

This shows how to set such a problem up and how to caculate the beam freq.

https://innovationspace.ansys.com/product/cantilever-beam-modal-analysis/
https://innovationspace.ansys.com/courses/courses/transverse-vibration-analysis-in-beams/lessons/natural-frequencies-for-various-end-conditions-lesson-2/

All the best

Erik