An electric motor, having an unbalance of \(2 \mathrm{~kg}-\mathrm{cm}\), is mounted at the end of a steel cantilever beam, as shown in Fig. 9.51. The beam is observed to vibrate with large amplitudes at the operating speed of \(1500 \mathrm{rpm}\) of the motor. It is proposed to add a vibration absorber to reduce the vibration of the beam. Determine the ratio of the absorber mass to the mass of the motor needed in order to have the lower frequency of the resulting system equal to 75 percent of the operating speed of the motor. If the mass of the motor is \(300 \mathrm{~kg}\), determine the stiffness and mass of the absorber. Also find the amplitude of vibration of the absorber mass.

Figure 9.51:-

Transcribed Image Text:

000 k m2 FIGURE 9.51 Absorber for unbalanced rotor.