The coupled effect of bearing misalignment and friction on vibration characteristics of a propulsion shafting system

Abstract

The propulsion shafting system of ships is usually supported, in part, by water-lubricated rubber bearings, which often work at mixed or boundary lubrication state under heavy-load and low-speed conditions, resulting in strong friction on the bearing-shaft interface and even abnormal vibration in the overall system. In addition, bearing misalignment can further affect the distribution of friction and consequently change the lateral and torsional vibration characteristics of the shafting system. In this work, the rubber bearing was simplified into parallel-distributed springs and the water film was neglected. The dynamic model of the propulsion shafting system was built with the finite element method and reduced by mode truncation. The coupled effect of bearing misalignment and friction was subsequently analyzed with this reduced model and the fourth-order Runge-Kutta method. Finally, lateral and torsional vibration characteristics of the overall system under different bearing misalignment were obtained, which can be used in the identification or diagnosis of abnormal vibration induced by friction.

Elimination of friction-induced vibration of a propulsion shafting system by auxiliary electromagnetic suspension

“…The velocity-dependent friction model (Qin et al, 2017(Qin et al, , 2019Zhang et al, 2014aZhang et al, , 2014b) is adopted to describe friction between the shaft and the bearing, in which the dynamic friction coefficient μ d is described with exponential formulation…”

“…The velocity-dependent friction model (Qin et al, 2017, 2019; Zhang et al, 2014a, 2014b) is adopted to describe friction between the shaft and the bearing, in which the dynamic friction coefficient μ d is described with exponential formulationwhere v r is the relative sliding velocity on the bearing-shaft interface, sgn(·) is the sign function and a 0 , b 0 and c 0 are constant parameters.…”

“…Also, stability analysis and numerical results revealed that the self-excited vibration is caused by the velocity-dependent friction and coupled dynamics of the system. The self-excited vibration of a shafting system in a gravity water tunnel was observed when the friction of the water-lubricated rubber bearing was tested (Qin et al, 2017(Qin et al, , 2019. It was found that the coupling between the torsional vibration of the flexible support and the friction of the bearing is the main factor resulting in instability.…”

Optimization of a New High Rotary Missile-Borne Stabilization Platform

“…The deep groove ball bearing which can bear radial load as well as some axial load and composed load is one type of non-separable bearing as well as the most typical structure of rolling bearing. Angular contact ball bearings have inner and outer ring raceways that are displaced relative to each other in the direction of the bearing axis, meaning that these bearings are designed to accommodate combined loads [30,31,32,33,34,35]. Fr and Fa are external radial and axial loads, C0 is the rated static load of the bearing, and S1, R2, R3, S1, S2, and S3 are geometric constants of the bearing.…”

Influence of electromagnetic bearings on lateral vibrations and sound radiation of a shaft-hull system

“…It has been found that the friction-induced lateral instability is responsible for the occurrence of stick–slip torsional oscillations. Qin et al 9,10 modeled a flexibly supported shafting system and found that the coupling between the torsional vibration of the flexible support and the friction of the water-lubricated rubber bearing is the main factor leading to vibration instability.…”