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/

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/

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

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.

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.

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