Modelling and Validation of a Rotor System With Ball Bearings

2010 ◽  
Author(s):  
Onur Cakmak ◽  
Kenan Y. Sanliturk
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Ball Bearing ◽  
Ball Bearings ◽  
Test Rig ◽  
Transform Method ◽  
Order Tracking ◽  
Bearing Defects ◽  
Gyroscopic Effects ◽  
Short Time

In this paper, a dynamic model of a rotor-ball bearing system is developed in Msc. ADAMS commercial software. Contacts between the balls and the rings are modelled according to Hertzian theory. The bearing model is capable of representing the effects of bearing defects and internal clearances. When they are coupled with the rotor structures, bearings without any defect can also cause excessive vibrations due to the resonance characteristics of the system. In order to demonstrate these characteristics the rotor itself is modelled as a flexible shaft and a disc positioned at the free end of the shaft. The rotor-ball bearing model developed here is capable of representing the gyroscopic effects and the behaviour of the system under different unbalance conditions. Various case studies are performed and Campbell diagrams are obtained by using short-time Fourier transform method. A test rig consisting of two ball bearings, a shaft and a disc is also designed and developed so as to validate the theoretical model using experimental data. The test rig is developed in such a way that all of the elements are easy to assemble/disassamble, allowing quick observation of the system’s dynamic behaviour for different parameters including imbalance, internal clearance and bearing defects. Modal analysis and order tracking analysis were carried out using the test rig. Both the modal results and Campbell diagrams obtained using experimental data are compared with their theoretical counterparts. In the light of the experimental data, the theoretical model is validated for the purpose of further analyses and research.

A dynamic model of an overhung rotor with ball bearings

2011 ◽  
Vol 225 (4) ◽  
pp. 310-321 ◽  
Author(s):  
O Cakmak ◽  
K Y Sanliturk
Keyword(s):  
Ball Bearing ◽  
Element Model ◽  
Contact Dynamics ◽  
Ball Bearings ◽  
Cage Structure ◽  
Order Tracking ◽  
Rolling Elements ◽  
Localized Defects ◽  
Gyroscopic Effects ◽  
Multi Body

A ball bearing comprising rolling elements, inner and outer rings, and a cage structure can be described as a multi-body system (MBS). In order to predict the dynamic behaviour and resonance characteristics of a rotor–ball bearing system, it can be modelled and analysed as a MBS with flexible and rigid parts. In this study, a ball bearing is modelled with MBS approach using MSC ADAMS commercial software. The Hertzian theory is used for modelling the contact dynamics between the balls and the rings. The ball bearing model is then assembled with the rotor model which comprised a shaft and a disc positioned at the free end of the shaft. The ball bearing model is used with both flexible and rigid shaft assumptions in order to highlight the differences between the two cases. For the flexible shaft case, the MBS model also included a finite element model of the shaft. As expected, it is necessary to include the flexibility of the shaft in the model in order to to predict the changes in the modal characteristics of the system as a function of the rotor speed. Furthermore, including the gyroscopic effects leads to observe the forward and backward travelling modes with different natural frequencies. The effects of the bearing diametral clearance and localized defects on the inner and outer rings are modelled and analysed using the model developed. Also, the effects of the rotor unbalance on the vibration level of the whole system are examined. A test rig – consisting of two ball bearings, a shaft, and a disc – is also designed and developed so as to validate the theoretical model using experimental data. Order tracking and modal analyses are carried out and Campbell diagrams are obtained. Finally, the theoretical and the experimental results are compared and a refined MBS model is obtained for further analyses.

Identification of Bearing Defects in Hybrid Thrust Ball Bearings by Vibration Analysis

2015 ◽  
Vol 825-826 ◽  
pp. 844-851 ◽  
Author(s):  
Arne Ziebell ◽  
Oskar Schöppl ◽  
Roland Haubner ◽  
Thomas Konegger
Keyword(s):  
Vibration Analysis ◽  
Relevant Information ◽  
Optimal Operation ◽  
Ball Bearings ◽  
Test Rig ◽  
Successful Operation ◽  
Bearing Defects ◽  
The Status ◽  
Key Aspects

Hybrid ball bearings, consisting of metallic washers in combination with ceramic bearing balls, feature a variety of significant advantages in comparison to standard steel bearings, including mechanical properties and reduced friction during operation. Key aspects for a successful operation are a prevention of defects of both balls and washers, as well as the knowledge of critical and optimal operation parameters. This relevant information can be obtained through test rig trials, where vibration analysis has found to be a versatile and efficient tool for the characterization of the operational status. In this contribution, hybrid thrust ball bearings with Si3N4 balls are investigated. After an introduction of defined damages in different parts of the bearing, test rig trials were conducted, and the vibration behavior during operation was compared to new, unused bearings. The characteristic vibrational frequencies, obtained through a variety of software-based filter and analysis algorithms, were correlated with materialographic investigations of failed bearings. The proposed method was shown to yield valuable information about damage morphologies and, subsequently, about the status of the bearing during operation.

Measuring and Analyzing the Moment of Friction in Double-Row Ball Bearings

2013 ◽  
Vol 199 ◽  
pp. 149-154
Author(s):  
Robert Korbut ◽  
Jerzy Nachimowicz
Keyword(s):  
Experimental Data ◽  
Working Conditions ◽  
Ball Bearing ◽  
Ball Bearings ◽  
Double Row ◽  
The Moment ◽  
Working Resistance ◽  
The Given

On the basis of the experiment, the changes in the moment of friction in the double-row ball bearing were estimated. The experimental data indicated the presence of significant differences between the average values of the moment of friction in the whole spectrum of the rotational speeds that were examined. At the same time it was observed that there exist certain characteristic rotational speeds at which the given bearing is informed by a greater working resistance. It may indicate the presence of both optimal and unfavourable working conditions for these bearings; the conditions during which there occur minimal or, respectively, maximal resistances (in a given situation). The results of the examination were analyzed statistically; the after-examination samples were closely observed and this further visual scrutiny proved that during the work of the bearing, the lubricant was displaced.

A Full Disturbance Model for Reaction Wheels

2014 ◽  
Author(s):  
M. P. Le ◽  
M. H. M. Ellenbroek ◽  
R. Seiler ◽  
P. van Put ◽  
E. J. E. Cottaar
Keyword(s):  
Theoretical Model ◽  
Attitude Control ◽  
European Space Agency ◽  
Theoretical Models ◽  
Ball Bearings ◽  
Reaction Wheel ◽  
Space Agency ◽  
Disturbance Model ◽  
Gyroscopic Effects ◽  
Characterization Test

Reaction wheels are rotating devices used for the attitude control of spacecraft. However, reaction wheels also generate undesired disturbances in the form of vibrations, which may have an adverse effect on the pointing accuracy and stability of spacecraft (optical) payloads. A disturbance model for reaction wheels was developed at Moog Bradford by combining empirical and theoretical models. The empirical data is obtained from a highly accurate reaction wheel characterization test setup from the European Space Agency and includes disturbance signals of ball bearings transmitted through the structures of the reaction wheel assembly. The theoretical model is derived from the equation of motion of a rigid rotor and a disc supported by two ball bearings including static, dynamic unbalances, structural modes and gyroscopic effects of the wheel rotor. To fully model the disturbance signature of the wheel, the bearing stiffness is formulated as a function of ball pass frequency and the flexibility of the supporting structural items like the reaction wheels housing are included. Finally, the empirical model is added into the theoretical model as excitations to form a full disturbance model for reaction wheels. The resulting combined model is then validated by tests on different types of Moog Bradford reaction wheels. The validated disturbance model is used to evaluate the pointing performance of spacecraft as well as to predict micro-disturbance performance for future reaction wheel designs.

scholarly journals Performance of 75-Millimeter Bore Arched Outer-Race Ball Bearings

1977 ◽  
Vol 99 (3) ◽  
pp. 346-352 ◽  
Author(s):  
H. H. Coe ◽  
B. J. Hamrock
Keyword(s):  
Experimental Data ◽  
Computer Program ◽  
Analytical Study ◽  
Ball Bearing ◽  
Ball Bearings ◽  
Shaft Speed ◽  
Operating Characteristics ◽  
Outer Race ◽  
Deep Groove ◽  
Deep Groove Ball Bearing

An investigation was performed to determine the operating characteristics of 75-mm bore, arched outer-race bearings, and to compare the data with those for a similar, but conventional, deep groove ball bearing. Further, results of an analytical study, made using a computer program developed previously, were compared with the experimental data. Bearings were tested up to 28,000 rpm shaft speed with a load of 2,200 N (500 lb). The amount of arching was 0.13, 0.25, and 0.51 mm (0.005, 0.010, and 0.020 in.). All bearings operated satisfactorily. The outer-race temperatures and the torques, however, were consistently higher for the arched bearings than for the conventional bearings.

Modal Interactions in Drillstring Borehole Interactions

2019 ◽  
Author(s):  
A. Kartheek ◽  
K. Vijayan ◽  
M. I. Friswell
Keyword(s):  
Theoretical Model ◽  
Numerical Technique ◽  
Operating Regime ◽  
Test Rig ◽  
Modal Interactions ◽  
Time Frequency ◽  
Bearing Stiffness ◽  
Space Formulation ◽  
Run Up ◽  
Gyroscopic Effects

Abstract Understanding the vibration of drillstrings is important for the economical and efficient extraction of oil. Vibrations involve bending, axial, and torsional vibration. Drillstring interaction with the borehole during whirling involves nonlinearities. For the present work the whirling interaction of the drillstring and borehole is studied using an equivalent conceptual experimental test rig and a theoretical model of the drillstring. The drillstring is modeled as an Euler Bernoulli beam with multiple discs considering damping and gyroscopic effects. The finite element method is used as a numerical technique and the eigenvalue problem is solved using a state space formulation. The forward whirling frequency obtained from the experiments was used to update the bearing stiffness of the theoretical model. The contact is modeled experimentally using a tube for the stator with added roughness to aggravate the friction effect. A run up analysis was carried out within the safe operating regime of the test rig and the frequencies were analyzed using a time frequency plot. The effect of typical system parameters was considered such as the location of the contact, the mode excited and the clearance. The results from the study indicated the possibility of interaction between the forward and backward whirling modes which increased the bandwidth of acceleration response.

scholarly journals Time-Domain Based Quantification of Surface Degradation for Better Monitoring of the Health Condition of Ball Bearings

Vibration ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 172-191
Author(s):  
Ayman Salem ◽  
Abdelrahman Aly ◽  
Sadok Sassi ◽  
Jamil Renno
Keyword(s):  
Time Domain ◽  
Health Condition ◽  
Second Phase ◽  
Ball Bearings ◽  
Test Rig ◽  
Bearing Defects ◽  
Defect Growth ◽  
Rolling Element ◽  
Innovative Solution ◽  
The Time Domain

This research aims to analyze the vibration response of damaged rolling element bearings experimentally and to assess their degree of degradation by examining parameters extracted from the time domain. This task was accomplished in three phases. In the first phase, a test rig was carefully designed and precisely manufactured. In particular, an innovative solution for rapidly mounting and dismounting bearings on the supporting shaft was tested and used successfully. In the second phase, a specific technique of seeding defects inside the ball bearings was developed. In the last phase, damaged bearings (and healthy ones serving as a reference) were installed on the test rig, and different vibration measurements were taken. The results obtained from this work show that different parameters could be extracted from the time domain. In addition to the six common indicators (peak, root mean square, crest factor, kurtosis value, impulse factor, and shape factor), four hybrid new ones have been proposed (Talaf, Thikat, Siana and, Inthar). The experimental results confirm the well-known efficiency of kurtosis in the detection of bearing defects. However, the newly proposed parameters were found to be more responsive to defect growth.

A Linear Theory of Vibrations Caused by Ball Bearings With Form Errors Operating at Moderate Speed

1992 ◽  
Vol 114 (2) ◽  
pp. 348-359 ◽  
Author(s):  
E. Yhland
Keyword(s):  
Theoretical Model ◽  
Linear Theory ◽  
Ball Bearing ◽  
Rotor Dynamics ◽  
Diameter Distribution ◽  
Ball Bearings ◽  
Centrifugal Forces ◽  
Form Errors ◽  
Geometrical Imperfections ◽  
Bearing System

A linear theoretical model is presented for the vibrations of a shaft bearing system caused by ball bearing geometrical imperfections. It is valid for low and medium speeds where ball centrifugal forces can be neglected. The excitation forces from each bearing are calculated and can serve as input to suitable rotor dynamics programs. Imperfections covered are radial and axial waviness of outer and inner rings, ball waviness and diameter distribution, nonuniform cage pocket distribution.

Temperature Rise Prediction of Oil-Air Lubricated Angular Contact Ball Bearings Using Artificial Neural Network

2019 ◽  
Vol 12 (3) ◽  
pp. 248-261
Author(s):  
Baomin Wang ◽  
Xiao Chang
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Temperature Rise ◽  
High Speed ◽  
Ball Bearing ◽  
Influence Factors ◽  
Ball Bearings ◽  
Ann Model ◽  
Angular Contact Ball Bearing ◽  
Artificial Neural

Background: Angular contact ball bearing is an important component of many high-speed rotating mechanical systems. Oil-air lubrication makes it possible for angular contact ball bearing to operate at high speed. So the lubrication state of angular contact ball bearing directly affects the performance of the mechanical systems. However, as bearing rotation speed increases, the temperature rise is still the dominant limiting factor for improving the performance and service life of angular contact ball bearings. Therefore, it is very necessary to predict the temperature rise of angular contact ball bearings lubricated with oil-air. Objective: The purpose of this study is to provide an overview of temperature calculation of bearing from many studies and patents, and propose a new prediction method for temperature rise of angular contact ball bearing. Methods: Based on the artificial neural network and genetic algorithm, a new prediction methodology for bearings temperature rise was proposed which capitalizes on the notion that the temperature rise of oil-air lubricated angular contact ball bearing is generally coupling. The influence factors of temperature rise in high-speed angular contact ball bearings were analyzed through grey relational analysis, and the key influence factors are determined. Combined with Genetic Algorithm (GA), the Artificial Neural Network (ANN) model based on these key influence factors was built up, two groups of experimental data were used to train and validate the ANN model. Results: Compared with the ANN model, the ANN-GA model has shorter training time, higher accuracy and better stability, the output of ANN-GA model shows a good agreement with the experimental data, above 92% of bearing temperature rise under varying conditions can be predicted using the ANNGA model. Conclusion: A new method was proposed to predict the temperature rise of oil-air lubricated angular contact ball bearings based on the artificial neural network and genetic algorithm. The results show that the prediction model has good accuracy, stability and robustness.

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