Journal of Sound and < ibration (2000) 229(4), 837 } 857 doi:10.1006/jsvi.1999.2526, available online at http://www.idealibrary.com on THE EFFECT OF DETUNING PARAMETERS ON THE ABSORPTION REGION FOR A COUPLED SYSTEM: A NUMERICAL AND EXPERIMENTAL STUDY OLKAN CUVALCI Department of Mechanical Engineering, ¹ exas ¹ ech ;niversity, ¸ubbock, ¹X 79409, ;.S.A. (Received 16 February 1999, and in ,nal form 6 July 1999) An approach for implementing a passive non-linear vibration controller for #exible 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 de#ections. 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 de"ne an absorption region numerically and experimentally with respect to forcing amplitude, internal frequency ratio and mass ratio for the passive vibration absorber.  2000 Academic Press 1. INTRODUCTION A useful technique for the elimination of undesirable vibration of problems of structural dynamics and machinery dynamics has been the application of one or more passive dynamic vibration absorbers. In this study, numerical and experimental applications of a passive vibration absorber for #exible structures are presented. For the numerical simulation, most of the energy is assumed to excite the "rst mode of the structure. The equation of motion was obtained by assuming that the cantilever beam with a tip mass and the pendulum system is subjected to large de#ections, resulting in non-linear coupling between the modes. The absorber is based on the saturation phenomenon of #exible structure exhibited by multi-degree-of-freedom (d.o.f.) systems with quadratic non-linearities possessing two-to-one autoparametric resonances. When the natural frequency of the controller (absorber) is set to one-half of the natural frequency of the structure (resonant mode), the non-linear coupling terms create a unidirectional energy-transfer mechanism that saturates the response of the resonant mode and reduces its vibration [1]. Watts developed the concept of the vibration absorber for the "rst time in 1883. The "rst application of a passive vibration absorber was 0022-460X/00/040837#21 $35.00/0  2000 Academic Press