The rotor shaft of a large electric motor supported between short bearings at both the ends shows a deflection of 1.8 mm in the middle of the rotor. Assuming the rotor to be perfectly balanced and supported at knife edges at both ends, the likely critical speed (in rpm) of the shaft is
705
Using the static-deflection estimate, ωn=√(g/δ)=√(9.81/0.0018)=73.82 rad/s. Critical speed is ωn60/(2π)=704.96 rpm≈705.
Important Questions from Resonance and Whirling
Which of the following parameters has higher value during whirling of a shaft?
The whirling speed of a rotating shaft depends on its _________.
According to Dunkerley’s empirical equation, the frequency of the transverse vibration of the system of several loads attached to the same shaft is
- Whirling of a shaft occurs when natural frequency of transverse vibration ________.
If two nodes are noticed at a frequency of 1800 rpm during whirling of a simply supported long slender rotating shaft, determine the first critical speed of the shaft (in rpm).
