A flexible machine part was observed to vibrate excessively at20 Hz due to a harmonic force of unknown amplitude. It wasconcluded that vibration was large because the harmonic forcecoincided with the natural frequency of the flexible part.
When the harmonic force was not present, a 0.5 kg mass wasplaced on the flexible part and a static displacement of 3.0 mm wasobserved. The mass was then removed.
a) The flexible part is to be modelled as a onedegree-of-freedom, mass-spring-damper system. What mass andstiffness would be appropriate?
b) A tuned vibration absorber is used to eliminate the vibrationat 20 Hz. If a mass of 0.03 kg is used for the absorber, whatstiffness is required?
c) If the amplitude of the absorber mass at 20 Hz was observedto be1 cm, what is the amplitude of the harmonic force acting onthe flexible part?
