Dynamic Characteristics of Ball Bearing-Coupling-Rotor System with Angular Misalignment Fault

2021 ◽  
Author(s):  
Pengfei Wang ◽  
Hongyang Xu ◽  
Yang Yang ◽  
Hui Ma ◽  
Duo He ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Ball Bearing ◽  
Element Model ◽  
Rolling Bearing ◽  
Rotor System ◽  
Radial Clearance ◽  
Axial Vibration ◽  
Restoring Force ◽  
Misalignment Fault

Abstract The rotor misalignment fault, which occurs only second to unbalance, easily occurs in the practical rotating machinery system. Rotor misalignment can be further divided into coupling misalignment and bearing misalignment. However, most of the existing references only analyze the effect of coupling misalignment on the dynamic characteristics of the rotor system, and ignore the change of bearing excitation caused by misalignment. Based on the above limitations, a five degrees of freedom nonlinear restoring force mathematical model is proposed, considering misalignment of bearing rings and clearance of cage pockets. The finite element model of the rotor is established based on the Timoshenko beam element theory. The coupling misalignment excitation force and rotor unbalance force are introduced. Finally, the dynamic model of the ball bearing-coupling-rotor system is established. The radial and axial vibration responses of the system under misalignment fault are analyzed by simulation. The results show that the bearing misalignment significantly influences the dynamic characteristics of the system in the low-speed range, so bearing misalignment should not be ignored in modeling. With the increase of rotating speed, rotor unbalance and coupling misalignment have a greater impact. Misalignment causes periodic changes in bearing contact angle, radial clearance, and ball rotational speed. It also leads to reciprocating impact and collision between the ball and cage. In addition, misalignment increases the critical speed and the axial vibration of the system. The results can provide a basis for health monitoring and misalignment fault diagnosis of the rolling bearing-rotor system.

Dynamic Characteristics Analysis of a Seal-Rotor System with Rub-Impact Fault

2021 ◽  
Author(s):  
Yuegang Luo ◽  
Pengfei Wang ◽  
Haifeng Jia ◽  
Fengchao Huang
Keyword(s):  
Dynamic Characteristics ◽  
Element Model ◽  
Rolling Bearing ◽  
Rotor System ◽  
Dynamic Responses ◽  
Force Model ◽  
Nonlinear Phenomena ◽  
Combination Frequency ◽  
Labyrinth Seals ◽  
Frequency Locking

Abstract Labyrinth seals are widely used to prevent fluid leakage in high-low pressure areas of the rotating machinery. However, the rub-impact fault easily occurs in labyrinth seals. Considering the influence of gyroscopic effect, a finite element model of seal-rubbing rotor system is established in this study based on the Muszynska seal force model, the rolling bearing force model and the nonlinear rubbing force model. The vibration characteristics under the coupling faults of airflow excitation and rub-impact are analyzed. Firstly, the response of the system without rub-impact fault is numerically simulated and verified by experiments. Subsequently, the dynamic characteristics of the rotor under the conditions of slight rub-impact and severe rub-impact faults are analyzed. Finally, the influence of the rub-impact parameters is further studied. The results indicate that when the rub-impact fault is absent, airflow excitation occurs at a certain speed, which exhibits the characteristics of frequency locking and combination frequency. The coupling dynamic responses of airflow-induced vibration and rub-impact fault show a rich spectrum of nonlinear phenomena, which is closely related to the degree of rub-impact. This study may provide a theoretical basis for the detection and diagnosis of fluid-induced rub-impact fault in labyrinth seal-rotor systems.

scholarly journals Vibration Responses of a Coaxial Dual-Rotor System with Supporting Misalignment

2021 ◽  
Vol 11 (23) ◽  
pp. 11219
Author(s):  
Hongxian Zhang ◽  
Xuejun Li ◽  
Dalian Yang ◽  
Lingli Jiang
Keyword(s):  
Dynamic Characteristics ◽  
Weight Ratio ◽  
Bending Moment ◽  
Element Model ◽  
Rolling Bearing ◽  
Moment Equation ◽  
Rotor System ◽  
Structural Deformation ◽  
Model Studies ◽  
Bearing Loads

In order to improve the thrust-weight ratio, modern aeroengines generally adopt a coaxial dual-rotor system. Factors such as manufacturing errors, assembly errors, bearing wear, and structural deformation can cause misalignment failures in a dual-rotor system. Supporting misalignment is one of the common types of misalignments in a dual-rotor system. To analyze the vibration characteristics of misalignment faults, in this study, we aim to build a finite element model of a dual-rotor system with supporting misalignment. The bearing loads caused by supporting misalignment are calculated using the three-bending moment equation method. Bearing loads are introduced into the dynamic model of the dual-rotor system. The influence of supporting misalignment at different bearings on the dynamic characteristics of the rotor system is investigated based on the supporting misalignment model. Studies have shown that supporting misalignment at different bearings has similar effects on the dynamic characteristics of the dual-rotor system. The proposed supporting misalignment model is more adaptable than the coupling misalignment model. It indicates that the damping of a rolling bearing should be considered in the dynamic analysis of a dual-rotor system although the value of the damping is not large. An experimental analysis is carried out. The simulation results are in good agreement with the experimental results.

Coupling effect of unbalanced magnetic pull and ball bearing on nonlinear vibration of motor rotor system

2020 ◽  
pp. 107754632098132
Author(s):  
Shaojie Guo ◽  
Changqing Bai
Keyword(s):  
Nonlinear Vibration ◽  
Dynamic Characteristics ◽  
Rotational Speed ◽  
Degrees Of Freedom ◽  
Ball Bearing ◽  
Coupling Effect ◽  
Asynchronous Motor ◽  
Rotor System ◽  
Unbalanced Magnetic Pull ◽  
Mass Eccentricity

In this article, the coupling effects of the unbalanced magnetic pull and ball bearing on nonlinear vibration of the three-phase asynchronous motor are investigated with the experimental and numerical methods. A test rig of a motor whose rotor supported by ball bearings is used and a 2 degrees of freedom magnetic solid coupling dynamic model of the motor rotor system is presented. The nonlinear dynamic response and spectrum are obtained from experiments and numerical analysis. The numerical results are in good agreement with test data, thus validating the presented model. It is found that the unbalanced magnetic pull and ball bearing forces possess the significantly interactional and nonlinear influences on the rotor dynamic characteristics. Small magnetic pull could impact the nonlinear bearing-rotor system, resulting in remarkable changes in the dynamic characteristics of the system. The effects of rotational speed and the rotor mass eccentricity on dynamic behaviors of the motor are discussed, and the results show that the magnetic pull gradually increases the amplitude of the ball bearing-rotor system, and its effect decreases with the increment of the rotational speed and mass eccentricity.

Finite Element Model Based Full Spectrum Response Analysis of a Cracked Rotor With Internal and External Damping

2019 ◽  
Author(s):  
Dipendra Kumar Roy ◽  
Rajiv Tiwari
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Rotor System ◽  
Response Analysis ◽  
Stable Operation ◽  
Internal Damping ◽  
Full Spectrum ◽  
Fault Parameters ◽  
Spectrum Response

Abstract The ratio of internal and external damping is one of the important fault parameters and it leads to instability of a rotor shaft at higher spin speeds. The crack in a rotor is one of the sources of its instability due to the crack internal damping. A rotor with crack internal damping that originates from the rubbing action between the two crack faces. For a sustained stable operation of the rotor, it is imperative to analyze rotor parameters such as the internal and external damping and other parameters, like the additive crack stiffness and disc eccentricity. Therefore, the present work considers a full spectrum response analysis of a transverse cracked shaft based on the finite element method. The rotary and translations of inertia are considered including of gyroscopic effect in the rotor system. The transverse crack is modeled based on the switching crack assumption. The crack in the rotor gives forcing with multiple harmonics with the forward and backward. The equation of motion has been developed for the rotor system having four degrees of freedom at each node and using MATLAB™ Simulink the responses are generated for a numerical example.

scholarly journals Dynamic Characteristics and Experimental Research of Dual-Rotor System with Rub-Impact Fault

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Hongzhi Xu ◽  
Nanfei Wang ◽  
Dongxiang Jiang ◽  
Te Han ◽  
Dewang Li
Keyword(s):  
Dynamic Characteristics ◽  
Element Model ◽  
Rotor System ◽  
Rotor Vibration ◽  
Double Frequency ◽  
Fundamental Frequencies ◽  
Outer Rotor ◽  
Dimensional Finite Element ◽  
Frequency Components ◽  
Collision Force

Rub-impact fault model for dual-rotor system was further developed, in which rubbing board is regarded as elastic sheet. Sheet elastic deformation, contact penetration, and elastic damping support during rubbing of sheet and wheel disk were considered. Collision force and friction were calculated by utilizing Hertz contact theory and Coulomb model and introducing nonlinear spring damping model and friction coefficient. Then kinetic differential equations of rub-impact under dry rubbing condition were established. Based on one-dimensional finite element model of dual-rotor system, dynamic transient response of overall structure under rub-impact existing between rotor wheel and sheet was obtained. Meanwhile, fault dynamic characteristics and impact of rubbing clearance on rotor vibration were analyzed. The results show that, during the process of rub-impact, the spectrums of rotor vibration are complicated and multiple combined frequency components of inner and outer rotor fundamental frequencies are typical characteristic of rub-impact fault for dual-rotor system. It also can be seen from rotor vibration response that the rubbing rotor’s fundamental frequency is modulated by normal rotor double frequency.

Damping the Vibrations of a Rigid Shaft Supported by Ball Bearings by Means of External Elastomeric O-ring Dampers

1994 ◽  
Vol 208 (3) ◽  
pp. 183-190 ◽  
Author(s):  
N Aktürk ◽  
R Gohar
Keyword(s):  
Computer Program ◽  
Frequency Response ◽  
Dynamic Characteristics ◽  
Ball Bearing ◽  
Ball Bearings ◽  
Axial Vibration ◽  
Response Curves ◽  
Elastomeric Dampers

In this paper the radial and axial vibration behaviour of a rigid shaft supported by a pair of back-to-back angular contact ball bearings, mounted on elastomeric O-ring dampers, is studied. The use of elastomeric dampers for reducing the untoward effects of vibrations, due to unbalance of the shaft centre, is investigated. A computer program was developed to simulate such situations with the results presented in the form of frequency response curves and shaft centre orbits. All results showed that elastomeric O-ring dampers can successfully be used for shaft-ball bearing systems as long as the dynamic characteristics of both the system and the elastomeric O-rings are known very well.

Influence of Pocket Wear on the Dynamic Characteristics of High-Speed Ball Bearing Cage

2019 ◽  
Author(s):  
Hui Li ◽  
Chen Li ◽  
Yuan Li ◽  
Shemiao Qi ◽  
Yi Liu ◽  
...  
Keyword(s):  
Dynamic Model ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Ball Bearing ◽  
Rolling Bearing ◽  
Outer Ring ◽  
Wear Loss ◽  
Vibration Modes ◽  
Mass Center ◽  
Fluctuation Amplitude

Abstract Aiming at the problem of wear on the cage-pocket during the operation of high speed rolling bearing, a dynamic model of high-speed ball bearing was established considering the wear loss of the ball-pocket, and the simulation was carried out to research on the interaction among the balls, the inner ring, the outer ring and the cage with different wear loss of the ball-pocket. The effect of the pocket wear on the trajectory of the cage’s mass center and the skidding ratio of cage was obtained. It was found out that the mass-center trajectory of the cage presents two vibration modes with different amplitudes which emerges alternatively. Moreover, the wear loss of the ball-pocket has little effect on the average skidding ratio of the cage, however, the fluctuation amplitude would become larger as the wear increase. This study can provide theoretical guidance for the design of bearing cage pocket size.

scholarly journals Analysis of Dynamic Characteristics for a Rotor System with Pedestal Looseness

2011 ◽  
Vol 18 (1-2) ◽  
pp. 13-27 ◽  
Author(s):  
Hui Ma ◽  
Xueyan Zhao ◽  
Yunnan Teng ◽  
Bangchun Wen
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Rotational Speed ◽  
Element Model ◽  
Rotor System ◽  
High Order Harmonic ◽  
Bifurcation Phenomenon ◽  
Frequency Components ◽  
Increasing Process ◽  
Harmonic Components

This paper presents a finite element model of a rotor system with pedestal looseness stemming from a loosened bolt and analyzes the effects of the looseness parameters on its dynamic characteristics. When the displacement of the pedestal is less than or equal to the looseness clearance, the motion of the rotor varies from period-one through period-two and period-three to period-five with the decreasing of stiffness of the non-loosened bolts. The similar bifurcation phenomenon can be also observed during the increasing process of the rotational speed. But the rotor motion is from period-six through period-three to period-four with the decreasing of the foundation stiffness. When the stiffness of the foundation is small and the displacement of pedestal is greater than the looseness clearance, the response of the rotor exhibits period-one and high order harmonic components with the decreasing of looseness clearance, such as 2X, 3X etc. However, when the stiffness of the foundation is great, the spectrum of the response of the rotor will be from combined frequency components to the continuous spectrum with the decreasing of the looseness clearance.

Sign in / Sign up

Export Citation Format

Share Document