Theoretical and experimental dynamics analysis of rotor-bearing system supported by elliptical bearings

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zhiming Zhao ◽  
Rui Zhang ◽  
Feng Ji ◽  
Xiaoyang Yuan
Keyword(s):  
Peer Review ◽  
Dynamic Characteristics ◽  
Critical Speed ◽  
Design Method ◽  
Large Diameter ◽  
Rotor System ◽  
Content Type ◽  
Vibration Data ◽  
Rotor Bearing ◽  
Bearing System

Purpose High power and speed are new demands for rotating machinery which needs the journal bearings with high dynamic characteristics. The critical speed of the rotor-bearing system is one of the most significant parameters to evaluate the dynamic characteristics. This paper aims to investigate the theoretical and experimental analysis of a rotor system supported by large diameter elliptical bearings. Design/methodology/approach To obtain the theoretical and experimental support for rotor-bearing system design, dynamic characteristics theoretical analysis based on the finite difference method is given and an experiment focuses on critical speed identification is carried out. Findings The theoretical calculation results indicate that the critical speed is near to 800 rpm and there is no large vibration amplitude round working speed (1,500 rpm). Using the test bench in the factory unit, vibration data including three experimental processes are obtained. According to the vibration data, the critical speed is identified which also indicates that it is stable when working at 1,500 rpm. Originality/value The design method for the rotor system supported by large diameter elliptical bearing can be obtained by the theoretical and experimental results shown in this paper. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0122/

Experimental dynamic analysis of rod-fastening rotor bearing system with a transverse crack

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nanshan Wang ◽  
Heng Liu ◽  
Qidan Wang ◽  
Shemiao Qi ◽  
Yi Liu
Keyword(s):  
Peer Review ◽  
Dynamic Characteristics ◽  
Vibration Amplitude ◽  
Critical Speed ◽  
Transverse Crack ◽  
Content Type ◽  
Rotor Bearing ◽  
Speed Up ◽  
Rod Fastening Rotor ◽  
Bearing System

Purpose This study aims to obtain the dynamic behaviours of cracked rod-fastening rotor bearing system (RFBS), and experimental investigation was carried out to examine the dynamic characteristics of this kind of assembled rotor bearing system with a transverse crack passing through the critical speed. Design/methodology/approach An experimental test rig of cracked RFBS was established for examining the vibration behaviours between intact and cracked system. The crack on the surface of a fastening rod was simulated by wire-electrode cutting processing method. The comprehensive analysis method of vibration was used to obtain the dynamic characteristics such as vibration amplitude, acceleration and whirling orbits before and after the critical speed as well as the instantaneous response in the process of speed up. Findings Some experimental vibration datum is obtained for cracked RFBS. The appearance of a crack will introduce the initial bending and make the vibration amplitude, acceleration and instant response in the process of speed up increase greatly as well as the change of whirling orbits. Originality/value The actual vibration characteristics for this complex assembled rotor system with a transverse crack are given passing through the critical speed. It can provide some useful help for monitoring the vibration behaviours of this kind of assembled rotor system as well as the detection of the crack fault. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0260/

Vibration and critical characteristics of the tilting pads journal bearing-rotor system

2019 ◽  
Vol 71 (2) ◽  
pp. 295-300 ◽  
Author(s):  
Zhiming Zhao ◽  
Feng Ji ◽  
Yongsheng Guan ◽  
Xiaoyang Yuan
Keyword(s):  
Theoretical Calculation ◽  
System Design ◽  
Critical Speed ◽  
Journal Bearing ◽  
Large Diameter ◽  
Vibration Monitoring ◽  
Content Type ◽  
Vibration Data ◽  
Rotor Bearing ◽  
Bearing System

Purpose High power rotating machinery requires large diameter bearings that can perform under extreme conditions. Vibrations and critical speeds of rotor supported by tilting pad journal bearing (TPJBs) exceeding their design limits may cause unit failure. This paper aims to investigate the experimental technique for large diameter bearings. Design/methodology/approach To obtain the experimental support for rotor-bearing system design, an experiment focusing on vibration monitoring is given. The sensors arrangement, monitoring system and critical speed identification method are provided. Findings By using test bench in factory unit, a large amount of vibrations data of different working situations is obtained. In addition, a method named non-excitation identification for critical speed is proposed. The critical speed of rotor identified through vibration data is given. The theoretical calculation results are also presented. Originality/value The basis for rotor-bearing system design can be obtained through comparisons between the experimental results and the theoretical calculation data.

Dynamic analysis of a helical geared rotor-bearing system with composite rotating shafts

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ying-Chung Chen ◽  
Xu Feng Cheng ◽  
Siu-Tong Choi
Keyword(s):  
Composite Material ◽  
Dynamic Analysis ◽  
Dynamic Characteristics ◽  
Mesh Stiffness ◽  
Content Type ◽  
Gear Mesh ◽  
Rotor Bearing ◽  
Rotating Shafts ◽  
Gear Mesh Stiffness ◽  
Bearing System

Purpose This study aims to study the dynamic characteristics of a helical geared rotor-bearing system with composite material rotating shafts. Design/methodology/approach A finite element model of a helical geared rotor-bearing system with composite material rotating shafts is developed, in which the rotating shafts of the system are composed of composite material and modeled as Timoshenko beam; a rigid mass is used to represent the gear and their gyroscopic effect is taken into account; bearings are modeled as linear spring-damper; and the equations of motion are obtained by applying Lagrange’s equation. Natural frequencies, mode description, lateral responses, axial responses, lamination angles, lamination numbers, gear mesh stiffness and bearing damping coefficients are investigated. Findings The desired mechanical properties could be constructed using different lamination numbers and fiber included angles by composite rotating shafts. The frequency of the lateral module decreases as the included angle of the fibers and the principal shaft of the composite material rotating shaft increase. Because of the gear mesh stiffness increase, the resonance frequency of the coupling module of the system decreases, the lateral module is not influenced and the steady-state response decreases. The amplitude of the steady-state lateral and axial responses gradually decreases as the bearing damping coefficient increases. Practical implications The model of a helical geared rotor-bearing system with composite material rotating shafts is established in this paper. The dynamic characteristics of a helical geared rotor-bearing system with composite rotating shafts are investigated. The numerical results of this study can be used as a reference for subsequent personnel research. Originality/value The dynamic characteristics of the geared rotor-bearing system had been reported in some literature. However, the dynamic analysis of a helical geared rotor-bearing system with composite material rotating shafts is still rarely investigated. This paper shows some novel results of lateral and axial response results obtained by different lamination angles and different lamination numbers. In the future, it makes valuable contributions for further development of dynamic analysis of a helical geared rotor-bearing system with composite material rotating shafts.

scholarly journals Dynamic Characteristics and Experimental Research of a Two-Span Rotor-Bearing System with Rub-Impact Fault

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Rui Zhu ◽  
Guang-chao Wang ◽  
Qing-peng Han ◽  
An-lei Zhao ◽  
Jian-xing Ren ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Critical Speed ◽  
Great Influence ◽  
Experimental Platform ◽  
Rotating Machine ◽  
Rotor Bearing ◽  
Before And After ◽  
Analysis System ◽  
The Stability ◽  
Bearing System

Rotor rub-impact has a great influence on the stability and safety of a rotating machine. This study develops a dynamic model of a two-span rotor-bearing system with rubbing faults, and numerical simulation is carried out. Moreover, frictional screws are used to simulate a rubbing state by establishing a set of experimental devices that can simulate rotor-stator friction in the rotor system. Through the experimental platform and its analysis system, the rubbing experiment was conducted, and the vibration of the rotor-bearing system before and after the critical speed is observed. Rotors running under normal condition, local slight rubbing, and severe rubbing throughout the entire cycle are simulated. Dynamic trajectories, frequency spectrum diagrams, chart of axis track, and Poincare maps are used to analyze the features of the rotor-bearing system with rub-impact faults under various parameters. The vibration characteristics of rub impact are obtained. Results show that the dynamic characteristics of the rotor-bearing system are affected by the change in velocity and degree of impact friction. The findings are helpful in further understanding the dynamic characteristics of the rub-impact fault of the two-span rotor-bearing system and provide reference for fault diagnosis.

scholarly journals Nonlinear Responses of a Rotor-Bearing-Seal System with Pedestal Looseness

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Junzhe Lin ◽  
Yulai Zhao ◽  
Pengfei Wang ◽  
Yuanyuan Wang ◽  
Qingkai Han ◽  
...  
Keyword(s):  
Working Conditions ◽  
Dynamic Characteristics ◽  
Critical Speed ◽  
Working Condition ◽  
Fault Model ◽  
Rotor System ◽  
Nonlinear Responses ◽  
Rotor Bearing ◽  
Multiple Frequencies ◽  
System Characteristics

In this paper, a pedestal looseness fault model of a rotor-bearing-seal system is established. Under two working conditions of the same direction eccentricity (Working Condition 1) and reverse eccentricity (Working Condition 2), rotor orbits, vibration waveforms, spectrum cascade, and Poincaré maps are used to study the dynamic characteristics of the system when the sliding bearing support is loosened. The influence of speed, the unbalance of two discs, the looseness clearance, and the mass of bearing support on system characteristics are analyzed. The study found that Working Condition 2 is more likely to cause looseness of the bearing support. Moreover, for the rotor system in this paper, the pedestal looseness fault is more likely to occur near the second-order critical speed. Through analysis of the spectrum, it is found that the spectrum of the looseness fault will show multiple frequencies or continuous spectra, and the rotor orbits will appear “cylindrical.”

Numerical and experimental study on dynamic characteristics of tilting-pad journal bearings considering pivot stiffness in a vertical rotor system

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fan Zhang ◽  
Peng Yin ◽  
Yuyang Liu ◽  
Jianmei Wang
Keyword(s):  
Dynamic Characteristics ◽  
Journal Bearings ◽  
Rotor System ◽  
Obvious Effect ◽  
Content Type ◽  
Vertical Rotor ◽  
Tilting Pad ◽  
Rotor Bearing ◽  
The Stability ◽  
Tilting Pad Journal Bearings

Purpose The purpose of this paper is to study the influence of pivot stiffness on the dynamic characteristics of tilting-pad journal bearings (TPJBs) and the stability of the bearing-rotor system. Design/methodology/approach A theoretical numerical model is established, and the influences of pivot stiffness on TPJBs and a bearing-rotor system are analyzed. Then, two kinds of pivot structures with different stiffness are designed and the vibration characteristics are tested on the vertical rotor bearing test bench. Findings The pivot stiffness has an obvious effect on the dynamic characteristics of the TPJBs and the stability of the bearing-rotor system. As a result of appropriate pivot stiffness, the critical speed and the vibration amplification factor can be reduced, the logarithmic decay rate and the stability of the rotor system can be effectively increased. While the journal whirl orbit is smoother and the rubbing is obviously reduced when the bearings have flexible pivots. Originality/value The influence of pivot stiffness on TPJBs and a vertical rotor-bearing system is studied by theoretical and experimental methods.

Effect of a transverse crack on the dynamic behaviours of a 3D rod-fastening rotor bearing system

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nanshan Wang ◽  
Heng Liu ◽  
Yi Liu ◽  
Qidan Wang ◽  
Shemiao Qi ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Model ◽  
Dynamic Characteristics ◽  
3D Finite Element ◽  
Content Type ◽  
Rotor Bearing ◽  
Rod Fastening Rotor ◽  
3D Finite Element Method ◽  
Bearing System

Purpose This paper aims to examine the dynamic behaviours of a three-dimensional (3D) rod-fastening rotor bearing system (RFBS) with a crack in a fastening rod. Design/methodology/approach Based on the 3D finite element method model and stress analysis of a cracked RFBS, a 3D dynamic model of the RFBS with a crack in a fastening rod is established with considering the initial bending and stress redistribution caused by the crack. A combined numerical simulation technology is used to investigate the dynamic behaviours of the system. Findings The distribution of contact stress between the two disks will be not uniform, and the initial bending of the system will occur due to the presence of a crack. This will lead to the change of system stiffness and the dynamic behaviours such as vibration amplitude, and motion orbits will change significantly. Research limitations/implications A 3D finite element method dynamic model is proposed for the study of dynamic characteristics of complex combined rotor bearing system with cracks. Practical implications It is helpful and significant to master the dynamic behaviours of cracked RFBS. It is helpful to detect the presence of a crack of the rotor bearing system. Social implications Some of the losses caused by crack failure may be reduced. Originality/value The proposed 3D method can provide a useful reference for the study of dynamic characteristics of complex combined rotor bearing system with cracks. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0189

Rotor Dynamics Analysis and Testing of a Turbomolecular Pump Rotor-Bearing System

2011 ◽  
Author(s):  
Chih-Neng Hsu ◽  
Hsiao-Wei D. Chiang ◽  
Yu-Meng Huang ◽  
Ying-Chia Fu ◽  
Kuo-Hsun Hsu ◽  
...  
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Dynamic Characteristics ◽  
Critical Speed ◽  
Experimental Measurements ◽  
Pump System ◽  
Pump Rotor ◽  
Turbomolecular Pump ◽  
Rotor Bearing ◽  
Bearing System

This study is focused on the dynamic characteristics of a vertical turbomolecular pump (TMP) rotor-bearing system. The research methods can be divided into two parts, which are numerical analysis and experimental measurements. In numerical analysis, we use the finite element analysis software DyRoBeS and ANSYS to construct a two- and three-dimensional models of the rotor-bearing system. In the analysis process, by using the pump system assembly testing data, we can verify the rotor-bearing system finite element models under different boundary conditions. Next, we calculate the Campbell diagram to study the dynamic characteristics of the rotor-bearing system, and to compare with the experimental results to verify the models. Finally, we found the relationship between the rotor critical speed and the bearing stiffness in order to study the design of the molecular pump rotor and the bearing system. Experimental measurements were divided into two parts: static modal tests and dynamic measurements. Static modal tests can provide the natural frequencies of the rotor-bearing system. Waterfall diagrams of the dynamic tests can measure the pump system critical speed from zero speed up to the working speed crossing, and to insure that the pump working speed is far from the critical speed of at least 10% in the safe margin. In summary, the results of the experimental measurements and numerical analysis can provide the basis for the design tool for turbomolecular pump rotor-bearing system in order to identify and prevent pump vibrations.

scholarly journals Transmissibility Analysis of a Regenerated Rotor System

2021 ◽  
Vol 9 (8) ◽  
pp. 1102-1107
Author(s):  
Akanksha Dhurvey
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Rotor System ◽  
Jet Engines ◽  
Simply Supported ◽  
Rotor Bearing ◽  
Unbalance Force ◽  
Force Transmissibility ◽  
Very High ◽  
Bearing System

Abstract: The aim of this paper is to represents a dynamic behavior of rotor bearing system wirth simply supported beam for three different position disc. rotating machinery such as compressors, turbines, pumps, jet engines, turtobo chargers, etc. are subject to vibrations. rotating machines are operated in very high speed and they are subjected to some unbalance force due to vibration from that machine pass to the foundation of machine.so the analysis of the dynamics parameter of rotor it is important to determine force transmissibility, natural frequency, critical speed and amplitudes of rotor system. Keywords: force transmissibility, vibration, critical speed, rotor bearing system etc.

Analytical and Experimental Study of Dynamic Characteristics of Rod Fastened Rotor-Bearing System Under Preload Saturation

2013 ◽  
Author(s):  
Mingjian Lu ◽  
Haipeng Geng ◽  
Guohui Xu ◽  
Lie Yu ◽  
Weimin Wang
Keyword(s):  
Dynamic Characteristics ◽  
Critical Speed ◽  
Contact Stiffness ◽  
Element Model ◽  
Analysis And Design ◽  
Contact Effect ◽  
Rotor Bearing ◽  
Equivalent Bending Stiffness ◽  
Rod Fastening Rotor ◽  
Bearing System

This paper investigates the dynamic characteristics of a composite rotor fastened by rods. Contact stiffness and equivalent bending stiffness between discs with different rod preloads of the rotor are obtained respectively by using the elastic and elastic-plastic contact theory. The finite element model of rotor-bearing system is built with Timoshenko beam elements. Critical speeds are respectively calculated with and without the consideration of contact effect, including the changing bearing dynamic coefficients. A test rig of rod fastening rotor-bearing system has been constructed to verify the numerical model results. The results show that the critical speed increases with rod preload and it keeps almost constant when the rod preload reaches a certain value, called preload saturation. The experiments demonstrate that the rod fastening rotor under preload saturation has the similar dynamic characteristics as integral rotor, such as the critical speed and backward whirl with asymmetric support stiffnesses. This kind of rotors which are under preload saturation can be analyzed and designed as an integral one without considering the contact effect. The study gives referential recommendations for analysis and design of a class of composite rotors which contain discs and rods.

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