An approach for implementing a passive non-linear vibration controller for flexible structures has been presented. The system consists of introducing the second order controller. When the structure is forced in the neighborhood of its resonance, the controller reduces the structure response. The structure consists of a cantilever beam with a tip mass. A pendulum is attached to the tip mass as a passive vibration controller. The equation of the motion was obtained by assuming that the cantilever beam and the pendulum were subjected to large deflections. In this study, autoparametric interaction was investigated by varying the forcing amplitude, the internal frequency ratio, and the mass ratio in the neighborhood of the autoparametric resonance. The objective of this study was to define an absorption region numerically and experimentally with respect to forcing amplitude, internal frequency ratio and mass ratio for the passive vibration absorber. (C) 2000 Academic Press.