Comparing the performance of a dynamic vibration absorber with a very large or very small moment of inertia

In this article, the performance of a two degree-of-freedom dynamicvibration absorber (DVA) with very large or very smallmoment of inertia is studied. Although it has been shown previouslythat an optimally tuned DVA with a negligibly small momentof inertia marginally outperforms the optimally tuned DVA with avery large moment of inertia, the physical reasons for this havenot been made clear. Using a simplified model of the stiffnesselements of the DVA, it is shown that the two sets of parallelcombinations of stiffness and damping elements of the DVA withnegligibly small moments of inertia effectively act in series, ratherthan in parallel as in the other case. Furthermore, it is shown thatthe stiffness and damping elements can be represented as a singlestiffness and a single damping element whose properties are frequencydependent. This frequency dependency means that there isadditional freedom in choosing the optimum stiffness and dampingof the DVA, which results in better performance