| Critical Speed
- Rotating a rotor assembly at its resonant frequency. The closer the rotational
speed is to the exact structural resonant frequency, the more the rotor
will vibrate. When operating below a critical speed, an unbalance mass
on the rotor will pull the rotor towards it. This is defined as
being a 'rigid' rotor. When operating above a critical speed, an unbalance
mass will push the rotor away from it. This is defined as being
a 'flexible' rotor. This phenomenon is why, when passing through a critical,
the rotor will experience a 180° phase shift (since the deflection
is in the opposite direction) and is an important characteristic that helps
identify a rotor's critical speed. |
Plot
Taken As Unit "Coasts-Down".
Note The
Amplitude Spike & Phase Shift
|
