Study on Coupling Fault Dynamics of Sliding Bearing-Rotor System

2019 ◽  
Vol 14 (4) ◽  
Author(s):  
Yang Liu ◽  
Xicheng Xin ◽  
Yulai Zhao ◽  
Shuaishuai Ming ◽  
Yaxin Ma ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Frequency Band ◽  
Rotor System ◽  
Sliding Bearing ◽  
Oil Film ◽  
Film Instability ◽  
Augmented Lagrange Method ◽  
Main Fault ◽  
Fault Dynamics ◽  
Coupling Fault

The phenomenon of oil film oscillation and frequency locked may occur in a healthy rotor system which is supported by sliding bearing. The dynamic behavior of the rotor system with misalignment and rubbing coupling fault supported by sliding bearing is also very complex. To solve the problem of fault diagnosis in this case, a dynamical model of rotor system is proposed in this paper. The short bearing oil film force, the equivalent misalignment moment, and Hertz contact theory are applied to establish the model. For rubbing faults, the Augmented Lagrange method is used to deal with the contact constraints to ensure that the boundary penetration depth is within the specified tolerance range. Furthermore, the dynamic behavior of the faulty rotor system under different rubbing stiffness conditions is analyzed in this paper. Meanwhile, the fault signal is divided into equal-band by the wavelet basis functions to find out the fault frequency band of the rotor system. Finally, the accuracy of the simulation study is verified by measurements obtained from the faulty rotor test platform. The following findings are made in this paper. The rubbing fault is dominant in the coupling fault. With the increasing of the speed, the frequency components of the system are dominated by high frequency. The double frequency is the main fault feature frequency band. It can be seen that the rotor system moves gradually from a quasi-periodic state into chaos due to the Lyapunov exponent. At the same time, due to the effects of misalignment moment and friction force, the phenomenon of oil film instability is partially suppressed. The lagging of the first and second-order oil film oscillations occurs.

scholarly journals Response Characteristics of Looseness-Rubbing Coupling Fault in Rotor-Sliding Bearing System

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Yang Liu ◽  
Zengyuan Xue ◽  
Lei Jia ◽  
Tuo Shi ◽  
Hui Ma
Keyword(s):  
Finite Element ◽  
Simulation Analysis ◽  
Element Model ◽  
Rotor System ◽  
Sliding Bearing ◽  
Oil Film ◽  
Response Characteristics ◽  
The Time Domain ◽  
Coupling Fault ◽  
Bearing System

For the diagnosis of looseness-rubbing coupling fault of rotor-sliding bearing system caused by bolt looseness fault, the mechanical model and finite element model of dual-disc rotor system with looseness-rubbing coupling fault are established based on the nonlinear finite element method, nonlinear oil film force, looseness stiffness model, and Hertz contact theory. With the augmented Lagrange method, contact constraint conditions are dealt with to ensure that the rotary disk and casing contact with each other meeting boundary penetrating depth within the prescribed tolerance range. And then the dynamics characteristics of the health rotor system supported by sliding bearing are studied. Combined with experimental study and simulation analysis, it is found that the looseness-rubbing coupling fault is often characterized by rubbing fault, the lower part of the time-domain fluctuated shape is denser, while the upper part is relatively loose, and multiple nested half ellipse is shown in orbit diagram. Because of the loosing stiffness and rubbing force, the phenomenon of unstable oil film is depressed. The appearance of the first- and second-order oil film oscillation phenomenon is delayed. It could be used as a theoretical basis for diagnosing looseness-rubbing coupling fault of rotor-sliding bearing system.

Oil-film instability simulation in an overhung rotor system with flexible coupling misalignment

2015 ◽  
Vol 85 (7) ◽  
pp. 893-907 ◽  
Author(s):  
Hui Ma ◽  
Xueling Wang ◽  
Heqiang Niu ◽  
Bangchun Wen
Keyword(s):  
Rotor System ◽  
Flexible Coupling ◽  
Oil Film ◽  
Film Instability

Experimental Research on Nonlinear Vibration Characteristics of Rotor Bearing System With Coupling Fault of Rub-Impact and Oil Whirl

2005 ◽  
Author(s):  
Changli Liu ◽  
Yimin Zhang ◽  
Qing Kai Han ◽  
Bangchun Wen
Keyword(s):  
Nonlinear Vibration ◽  
Experimental Research ◽  
Vibration Characteristics ◽  
Rotor System ◽  
Harmonic Vibration ◽  
Oil Film ◽  
Oil Whirl ◽  
Rotor Bearing ◽  
Coupling Fault ◽  
Bearing System

An experimental rotor rig was developed to investigate nonlinear vibration characteristics of rotor bearing system with coupling fault of rub-impact and oil whirl. It was found that when the effect of oil film force on a rub-impact rotor system is comparatively weak, the rotor/stator rub-impact will cause the system to give rise to sub- and super-harmonic vibration components. In a rub-impact rotor system with oil whirl fault, super-harmonic vibration components were excited, when rotor/stator rub-impact happens before oil film whirl because of small rotor/stator clearance. When the rotor/stator clearance is comparatively large, the rub-impact happens after oil film whirl, and the effect of rub-impact on the rotor system will be very weak.

scholarly journals Dynamical Behavior Analysis of Rubbing Rotor System under Asymmetric Oil Film Force

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Youfu Tang ◽  
Feng Lin ◽  
Qian Zou
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Models ◽  
Journal Bearing ◽  
Dynamic Theory ◽  
Dynamical Behavior ◽  
Rotor System ◽  
System Response ◽  
Oil Film ◽  
Rotor Structure ◽  
Rotor Dynamic

Rubbing is one of the most common and significant faults that exist in the rotor system. It exhibits extremely complicated dynamic behavior. Existing dynamic models are primarily based on the symmetrical rotor structure, in which the oil film forces at both ends of support are considered identical. However, in practice, the oil film force may be differently affected by multiple factors (e.g., viscosity of lubricants, the thickness of oil film, and clearance of journal bearing). In this study, a novel dynamic model of the rubbing rotor system under asymmetric oil film force was developed. Furthermore, based on the nonlinear rotor dynamic theory, its dynamic behavior with different parameters was analyzed, and the corresponding chaotic features were extracted. The results indicated that the evolution law of chaotic motion was more complicated, and the chaotic region of system response was obviously wider under the asymmetric oil film force than the symmetrical oil film force.

The Fault Analysis and Research of Turbine Generator Sliding Bearing Oil Film Instability

2014 ◽  
Vol 915-916 ◽  
pp. 198-202
Author(s):  
Guo Dong Han ◽  
Zhang Qin Wu ◽  
Shu Ting Wan ◽  
Zhan Jie Lv ◽  
Rong Hai Liu ◽  
...  
Keyword(s):  
Spectral Characteristics ◽  
Fault Analysis ◽  
Turbine Generator ◽  
Sliding Bearing ◽  
Oil Film ◽  
Oil Whip ◽  
Film Instability ◽  
Oil Whirl ◽  
Whirl Speed ◽  
The Time Domain

This article are discussed Sliding Bearing for Turbine instability failure research status in detail; Gives the theoretical analysis On sliding bearing oil film instability failure mechanism, to further explore the oil whirl and oil whip manifestations and signal spectral characteristics. And analysis of the oil whirl speed changes the vibration characteristics of typical regions, given the time-domain waveform oil whirl and oil whip axis trajectory. Details of the turbine generator film and the main reason for the instability factors and made a film instability fault governance approach. It helped for Fault Diagnosis of Turbine film and achieving security and stability of Turbine provides technical reference.

Identification of Modal Parameters of an Elastic Rotor With Oil Film Bearings

1984 ◽  
Vol 106 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Rainer Nordmann
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Design Process ◽  
Mechanical Engineering ◽  
Mechanical Systems ◽  
Rotating Machinery ◽  
Modal Parameters ◽  
Powerful Method ◽  
Oil Film ◽  
Engineering Problems

Investigations of the dynamic behavior of structures have become increasingly important in the design process of mechanical systems. To have a better understanding of the dynamic behavior of a structure, the knowledge of the modal parameters is very important. The powerful method of experimental modal analysis has been used to measure modal parameters in many mechanical engineering problems. But the method was mainly applied to nonrotating structures. This presentation shows improvements of the classical modal analysis for a successful application in rotating machinery with nonconservative effects. An example is given, investigating the modal parameters of an elastic rotor with oil film bearings.

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