scholarly journals Research on Vibration Suppression Method Based on Coaxial Stacking Measurement

Mathematics ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1438
Author(s):  
Chuanzhi Sun ◽  
Ruirui Li ◽  
Ze Chen ◽  
Yingjie Mei ◽  
Xiaoming Wang ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Vibration Suppression ◽  
Rotor System ◽  
Vibration Response ◽  
Analysis Model ◽  
Assembly Method ◽  
Multi Stage ◽  
Excitation Force ◽  
Rotor Mass ◽  
Force Vectors

A dynamic analysis model of the unbalanced vibration response of a single-rotor system is established to study the corresponding mechanism of the unbalanced excitation force and vibration response caused by the deviation of the rotor mass centroid in this paper, and finally to achieve the combined rotor vibration suppression. First, the installation of multi-stage rotors during vibration was studied, and the rotor mass centroid transfer model in the rotating coordinate system was established to obtain the unbalanced excitation force vectors of the rotors at all levels based on the traditional stacking assembly method and axiality measurement. Second, the rotor unbalance excitation force vectors were substituted at all levels to establish the finite element analysis model of the single-rotor system. Finally, a simulation analysis was carried out for the stacking assembly of the three-stage rotor, and the rotor test piece was used for the vibration experiment. The results show that the optimal assembly phase of the multi-stage rotor obtained by the dynamic analysis model of the unbalanced vibration response of the single-rotor system can effectively suppress the vibration of the combined rotor.

Dynamic analysis of a planar multi-stage centrifugal pump rotor system based on a novel coupled model

2018 ◽  
Vol 434 ◽  
pp. 237-260 ◽  
Author(s):  
Wenjie Zhou ◽  
Ning Qiu ◽  
Leqin Wang ◽  
Bo Gao ◽  
Dong Liu
Keyword(s):  
Dynamic Analysis ◽  
Centrifugal Pump ◽  
Coupled Model ◽  
Rotor System ◽  
Pump Rotor ◽  
Multi Stage

A Lower Pad Adjustable Bearing Reducing Vibration Response of Rotor Systems During Acceleration

2019 ◽  
Author(s):  
Lei Zhang ◽  
Hua Xu ◽  
Shenglun Zhang ◽  
Shiyuan Pei
Keyword(s):  
Critical Speed ◽  
Vibration Suppression ◽  
Load Condition ◽  
Element Model ◽  
Rotor System ◽  
Vibration Response ◽  
Resonance Amplitude ◽  
Suppression Effect ◽  
Rotor Systems ◽  
Light Load

Abstract A lower pad movable bearing is proposed which has the ability to change the lubricating performance of the journal bearing. The structure and working principle of the adjustable bearing are introduced. This bearing can adjust the working status of the rotor system by changing the position of the bearing pad and reduces the vibration amplitude of rotor. In this paper, a simple rotor bearing finite element model is used to study the vibration response of the rotor system. Through research, it is found that larger ellipticity can effectively reduce the amplitude of the rotor when the rotor speed is running at a certain speed away from the critical speed, and the vibration suppression effect can reach 67%. When the rotor passes the critical speed, reducing the ellipticity can significantly reduce the resonance amplitude of the rotor, and the vibration suppression effect reaches about 37%. In addition, when the rotational speed increases to twice the critical speed, the oil film oscillation occurs under light load condition, which can be suppressed by reducing the ellipticity. Adjustable bearing can then be proposed to adaptively improve the vibration of the rotor system based on the rotor speeds.

Dynamic Analysis of Cage Stress in Tapered Roller Bearings Using Component-Mode-Synthesis Method

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Tomoya Sakaguchi ◽  
Kazuyoshi Harada
Keyword(s):  
Rigid Body ◽  
Dynamic Analysis ◽  
Boundary Point ◽  
Axial Load ◽  
Synthesis Method ◽  
Load Condition ◽  
Component Mode Synthesis ◽  
Analysis Model ◽  
Tapered Roller ◽  
Tapered Roller Bearings

In order to investigate cage stress in tapered roller bearings, a dynamic analysis tool considering both the six degrees of freedom of motion of the rollers and cage and the elastic deformation of the cage was developed. Cage elastic deformation is equipped using a component-mode-synthesis (CMS) method. Contact forces on the elastically deforming surfaces of the cage pocket are calculated at all node points of finite-elements on it. The location and pattern of the boundary points required for the component-mode-synthesis method were examined by comparing cage stresses in a static condition of pocket forces and constraints calculated by using the finite-element and the CMS methods. These results indicated that one boundary point lying at the center on each bar is appropriate for the effective dynamic analysis model focusing on the cage stress, especially at the pocket corners of the cages, which are actually broken. A behavior measurement of a polyamide cage in a tapered roller bearing was conducted for validating the analysis model. It was confirmed in both the experiment and analysis that the cage whirled under a large axial load condition and the cage center oscillated in a small amplitude under a small axial load condition. In the analysis, the authors discussed the four models including elastic bodies having a normal eigenmode of 0, 8 or 22, and rigid-body. There were small differences among the cage center loci of the four models. These two cages having normal eigenmodes of 0 and rigid-body whirled with imperceptible fluctuations. At least approximately 8 normal eigenmodes of cages should be introduced to conduct a more accurate dynamic analysis although the effect of the number of normal eigenmodes on the stresses at the pocket corners was insignificant. From the above, it was concluded to be appropriate to introduce one boundary point lying at the center on each pocket bar of cages and approximately 8 normal eigenmodes to effectively introduce the cage elastic deformations into a dynamic analysis model.

Dynamic analysis for a spur geared rotor system with tooth tip chipping based on an improved time-varying mesh stiffness model

2021 ◽  
Vol 165 ◽  
pp. 104435
Author(s):  
Yi Yang ◽  
Niaoqing Hu ◽  
Jinyuan Tang ◽  
Jiao Hu ◽  
Lun Zhang ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Rotor System ◽  
Time Varying ◽  
Mesh Stiffness ◽  
Stiffness Model

Local defect modelling and nonlinear dynamic analysis for the inter-shaft bearing in a dual-rotor system

2019 ◽  
Vol 68 ◽  
pp. 29-47 ◽  
Author(s):  
Peng Gao ◽  
Lei Hou ◽  
Rui Yang ◽  
Yushu Chen
Keyword(s):  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Rotor System ◽  
Local Defect

Android Botnets

2021 ◽  
pp. 75-92
Author(s):  
Ahmad Karim ◽  
Victor Chang ◽  
Ahmad Firdaus
Keyword(s):  
Dynamic Analysis ◽  
High Accuracy ◽  
Remote Access ◽  
Learning Approaches ◽  
Analysis Model ◽  
Hybrid Analysis ◽  
Static And Dynamic Analysis ◽  
Mobile Botnet ◽  
Wide Scale ◽  
Access Information

Mobile botnets are gaining popularity with the expressive demand of smartphone technologies. Similarly, the majority of mobile botnets are built on a popular open source OS, e.g., Android. A mobile botnet is a network of interconnected smartphone devices intended to expand malicious activities, for example; spam generation, remote access, information theft, etc., on a wide scale. To avoid this growing hazard, various approaches are proposed to detect, highlight and mark mobile malware applications using either static or dynamic analysis. However, few approaches in the literature are discussing mobile botnet in particular. In this article, the authors have proposed a hybrid analysis framework combining static and dynamic analysis as a proof of concept, to highlight and confirm botnet phenomena in Android-based mobile applications. The validation results affirm that machine learning approaches can classify the hybrid analysis model with high accuracy rate (98%) than classifying static or dynamic individually.

scholarly journals Adapted Wavelet Transform for Twisted Blade Diagnosis in Multi Stage Rotor

2019 ◽  
Vol 255 ◽  
pp. 02011
Author(s):  
Ahmed M. Abdelrhman ◽  
M. Salman Leong ◽  
Y.H. Ali ◽  
Iftikhar Ahmad ◽  
Christina G. Georgantopoulou ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Rotor System ◽  
Fault Detection And Diagnosis ◽  
Frequency Resolution ◽  
Time Frequency ◽  
Multi Stage ◽  
The Common ◽  
Detection And Diagnosis ◽  
Twisted Blade

This paper studies the diagnosis of twisted blade in a multi stages rotor system using adapted wavelet transform and casing vibration. The common detection method (FFT) is effective only if sever blade faults occurred while the minor faults usually remain undetected. Wavelet analysis as alternative technique is still unable to fulfill the fault detection and diagnosis accurately due to its inadequate time-frequency resolution. In this paper, wavelet is adapted and its time-frequency is improved. Experimental study was undertaken to simulate multi stages rotor system. Results showed that the adapted wavelet analysis is effective in twisted blade diagnosis compared to the conventional one.

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