The critical speeds for torsional vibrations of an engine and its driven system are not influenced appreciably by small amounts of inherent damping. However, if damped vibration absorbers, fluid couplings, and other components containing considerable damping are present, the peak amplitudes of displacement of the various masses of the system will not occur at a common frequency and the concept of resonance loses its usual meaning. It is recommended that the response of the damped system be investigated when large damping mechanisms are present.
