In the 1st report, we experimentally indicated the possibility of vibration control in terms of axially moving belt systems by producing torque fluctuation that causes parametric excitation. In order to clear generalities concerning vibration occurrence and vibration control of the belt system, the corresponding theoretical analysis is required. In this paper, we suggest forced vibration generated the pulley unbalance and vibration control owing to parametric excitation induced by the fluctuation of the belt speed. The belt system is analyzed by quasi-modal model transformed by inner system mode and deflection mode. As the result, quasi-modal model was applicable for forced vibration acting on a nodal point. The obtained results with respect to the forced vibration and the vibration control agree well with experimental data.
