Untitled as of 10/13/97 (TBA)

N. Sri Namachchivaya, Nonlinear Sys. Group, Aero & Astro Eng. Dept., Univ. of Ill-Urbana Champaign

In this talk, we present nonlinear dynamics of certain gyroscopic and aeroelastic systems near resonances, subject to internal damping, symmetry-breaking and time periodic perturbations. The interplay between these three effects results in a variety of local and global bifurcations. While deriving these equations of motion, many studies in the past have neglected some nonlinear terms as insignificant which, in fact, may completely change the bifurcation behavior. In both gyroscopic and aeroelastic systems it is the nonlinear dissipative terms that can change the behavior, and it is essential to carefully model these terms in the physical problems. For general nonlinear gyroscopic and aeroelastic systems, we present these effects as various bifurcation results due to symmetry-breaking imperfections. In the case of the gyroscopic systems the symmetry is broken by the addition of imperfections while for general aeroelastic systems, the reversible symmetry is broken by the addition of unsteady aerodynamic terms.