Hi,
Do you have an example for running a modal analysis
- Motor- Rotor shaft ?
- Gear box shaft ?
- shafts with bearings ?.
- Rotating shaft ?
There are some CalculiX examples: https://www.youtube.com/watch?v=hMKta2HfEbs
But you can find more examples done in other software (ANSYS) that could be recreated in PrePoMax. CalculiX has a complex eigenfrequency analysis procedure meant for rotordynamics: Complex frequency result confused - CalculiX (official versions are on www.calculix.de, the official GitHub repository is at https://github.com/Dhondtguido/CalculiX).
Whirling of Shafts | Theoretical Vs Computational | ANSYS Modal Analysis | Xdynemo - YouTube
Can we use the above scenario?. When Prepomax displays the mode and frequency after analysis, does it display the critical frequency along with mode?.
Is it a good practice to support the shafts at the bearing locations or it does not matter !..
Maximum RPM of shaft will be 3300.
Regular modal analysis will only give you the natural frequencies (those at which resonance may occur) and their associated mode shapes without accounting for rotation speed. A proper rotordynamics analysis would require a static step including a centrifugal load with a specific rotation speed. Then regular and complex frequency steps should follow. Based on that, you can create a Campbell diagram with natural frequency vs rotation speed (you need a few runs with different speeds) for each mode. Then you add straight lines representing natural frequencies and their intersections with the curves found in the analyses will give you critical speeds.
Check this thread too: Modal Analysis of Centrifugal Compressor Impeller
Yes, you have to place the supports where bearings are and constrain proper DOFs.