Use of a Flexible Internal Support to Suppress Vibrations of a Rotating Shaft Passing Through a Critical Speed

Abstract

As is widely known, large vibrations may occur when a rotating shaft passes through one of its critical speeds. To suppress these large motions, it may be possible to modify the system as it is accelerating or decelerating in such a way as to avoid this resonance phenomenon. This is accomplished with the use of a flexible internal support that can be activated or deactivated during run-up or run-down of the system. The shaft has an unbalanced disk, and the nonstationary analysis includes gravitational forces and internal and external damping. The system is driven by a motor that may be nonideal (with a limited power supply) or ideal. Although transient motions are caused when the system stiffness is changed, the resulting maximum displacement may be significantly less than that of the original system passing through a critical speed.