FLUTTER AND DIVERGENCE INSTABILITY OF NONCONSERVATIVE BEAMS AND PLATES

For a conservative system, the only possible instability is of diverge nce type. For a nonconservative system, however, instability can be of divergence, Butter or both, depending on the amount of nonconservativ eness. In this paper, we study the instability of a cantilevered beam and a simply supported plate, subjected to a combination of fixed and follower Forces. A nonconservative parameter is introduced to provide all possible combinations of these forces. For the beam, instability c hanges from divergence to Butter at a critical value of this parameter . For values of the parameter above the critical value, the Butter ins tability remains as the only instability pattern, in contrast to impli cations in the literature. For the plate, the instability is governed by Butter for a certain range of the nonconservative parameter, even t hough divergence instability still exists. The range depends on the ge ometry (aspect ratio) and material property (Poisson's ratio) of the p late.