Abstract
The fixed points theory is applied for the dynamic absorber attached to two degree of freedom system which consists of two identical single degree of freedom systems connected in series. The frequencies of fixed points and the ratio of natural frequencies to equalize the amplitudes at fixed points are analytically derived, in case that the responses at fixed points are in phase. The damping coefficients which make fixed points extremal value are also obtained. The geometric mean of the damping coefficients is suitable. Comparison of the analytical solution and numerically computed results whose responses at fixed points of equal amplitudes are π rad out of phase, shows that these dynamic absorbers have almost same performance of vibration suppression.
