STIFFENING EFFECT OF CENTRIFUGAL FORCE ON COUPLED VIBRATION OF A BEAM OF LINEARLY VARYING CHANNEL CROSS-SECTION UNDER UNSTEADY AERODYNAMIC FORCES

摘要

The stiffening effect of Centrifugal force on the fundamental frequency and critical speed of coupled vibrations of a rotating slender beam of varying channel cross-section under unsteady aerodynamic coupling is investigated. A method has been used to obtain an upper bound for fundamental frequency and further the accuracy of this upper bound is investigated by considering the application of this method to uncoupled vibration. It has been found that the fundamental frequency may be considerably increased with the decrease in the area of cross-section of the free end of the rotating beam. It has also been found that the fundamental frequency and critical speed depend upon the ratio of hub radius to blade length and upon angle ψ made by the minor axis of intertia with the direction of centrifugal velocity.