CRITERIA FOR OCCURRENCE OF FLUTTER INSTABILITY BEFORE BUCKLING IN NONCONSERVATIVE DISSIPATIVE SYSTEMS

The occurrence of flutter instability through a Hopf bifurcation befor e static buckling in regions of divergence in nonconservative, nonself -adjoint, dissipative systems is thoroughly discussed using a qualitat ive analysis. This region where both Ziegler's and static criterion ma y fail to predict the actual critical load is defined via two values ( bounds) of the nonconservativeness loading parameter eta; the upper bo und corresponds to eta = 0.5 (being invariant with respect to all othe r parameters), whereas the lower bound corresponds to a double critica l (divergence) point beyond which there are no adjacent equilibria. Th e location of the last point (lying always between eta = 0 and 0.5) de pends on a stiffness parameter. It is also found that the region of no nexistence of adjacent equilibria becomes maximum (minimum) when the d ouble critical point corresponds to eta = 0.5 (eta = 0). The interacti on of vanishing damping with various parameters leads to new phenomena related to point and periodic attractors as well as to a new type of dynamic bifurcation.