A structure is supporting rotating machine that vibrates excessively at an excitation
frequency of 18 Hz as shown in Figure 1. It is proposed to attach a vibration absorber
tuned to this frequency. What should be the absorber’s mass and stiffness so that the
resulting two natural frequencies are at least 20% away from the excitation frequency?
The effective mass of structure supporting the machine is 1000 kg and it’s natural
frequency is 16Hz.Figure 1.