A massless elastic shaft carries two rotors. With each rotor considered separately at its own position, the transverse natural frequencies are 100 Hz and 200 Hz. Using Dunkerley’s approximation, estimate the lowest critical speed of the combined system.
5367 rpm
Dunkerley’s approximation gives \(1/f_c^2=1/100^2+1/200^2\), hence fc = 89.4427 Hz. Multiplying by 60 yields 5366.56 rpm ≈ 5367 rpm.
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).
