Coupling vibration characteristics of the shaft-disk-drum rotor system with bolted joints

Abstract

In this paper, a finite element (FE) model for rotating-flexible shaft-disk-drum (SDR) system with bolted joints is established based on beam-shell-spring hybrid elements by in-house codes. Rotation-induced effects, that is, centrifugal effect, initial tension, gyroscopic moments, and geometric non-linearity due to large deformation are taken into account. Besides, fixed interface mode synthesis method is applied to improve solving efficiency. The proposed model is verified by the results from literature and experiments. Finally, the effects of the number of bolts, rotating speed, connecting stiffness, and the location of disk-drum on the natural characteristics of SDR system are investigated. The main conclusions are summarized as follows: (1) Modes dominated by different components have different sensitivities to the variations of the number of bolts. (2) The analysis of Campbell diagram indicates that frequency veering phenomenon can be found among the shaft bending (SB) mode, disk transverse (DT) mode, disk swing (DS) mode and drum one-circumferential wave (1CW) mode in low-order modes, and the disk nodal diameter (ND) mode always couples with the drum CW mode in high-order modes. (3) The change of axial connecting stiffness will cause the coupling vibration between the disk and drum, while the change of transverse shear stiffness not only causes the coupling vibration between the disk and the drum, but also the coupling vibration among the shaft, disk and drum. (4) The change of disk-drum location can affect the modes associated with the shaft SB and cause frequency veering phenomena. The disk ND modes and the drum CW modes are not coupled with the shaft SB modes when the number of ND and CW are greater than 2.