An automotive engine weighing 240 kg is supported on four springs with linear characteristics. Each of the front two springs have a stiffness of 16 MN/m while the stiffness of each rear spring is 32 MN/m. The engine speed (in rpm), at which resonance is likely to occur, is
6040
For vertical translation, the four springs act in parallel: keq=2(16)+2(32)=96 MN/m. Natural angular frequency is √(96×10⁶/240)=632.46 rad/s. For once-per-revolution excitation this corresponds to 6039.5 rpm≈6040.
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).
