Supporting arm vibration and deflection
The rotor vibration might build up if the rotor rpm (with its harmonics)
is operated constantly at a fixed rpm that coincide with the structure
natural frequency. The rough estimation of frequency is made by assuming
the support arm as a spring while the other hanging components as rigid
mass and the supporting components as fixed support. This will not provide
the real structure natural frequency (real value will be lower of course)
but just as a comparison of how stiff this part of structure is compare
to the other parts. The pair of flat plates support arm will have the
possibility to act like a single beam, which will be very stiff, or as
two independent beam which will be much less stiffer. Anyway, the calculated
frequencies for both are well above the maximum rotor rpm. The deflection
of this stiff arm is small as expected and the low stress calculation
is skipped. It is assumed that the mild steel flat plates is 15mm wide,
2.5mm thick, and 2500mm long with distance between two plates, H equals
2cm.
Lateral vibration of support arm
|
