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Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Early detection of bearing faults is an essential task of machine health monitoring. The bearings are one of the vital components of rotary machines. Various methods and techniques were used over the time to diagnose and improve the bearing fault analysis. This review paper includes a fourfold study on the fault analysis. First, the decomposition methods used for signal processing and extracting the required features are discussed under vibrational analysis for health monitoring. Second, the analysis on oil–air lubrication and thermal models used to study the temperature variations are studied. Third, analysis on sensor placement to select an optimal position in collecting the original signals with least possible disturbances was discussed in detail. Finally, in the fourth section, neural networks used for the fault diagnosis is reviewed and analysed. Methods: The convolutional neural network (CNN), Bayesian neural network (BNN), and probabilistic neural network (PNN) are the techniques most commonly used by researchers recently. Among the networks, CNN with modifications is found to provide high accuracy and robustness in identifying and classifying bearing faults even in noisy environments. Results: Discrete wavelet transform (DWT) method for the feature extraction. Daubechies four (db4) with five-layer decomposition method was used to identify the severity of bearing defects. Also, Orthogonal Fuzzy Neighbourhood Discriminant (OFND) features were extracted. This survey analysed existing works on fault diagnosis on spherical roller bearing in different perspectives. Conclusion: Among all the decomposition methods, variational mode decomposition was the most commonly used method and also found to be very effective compared to other methods. The intrinsic time scale method also finds a reasonable part in many research works. Also, various types of neural networks were used in which CNN and modifications to CNN were mostly used to automatically acquire the sensitive fault information from the decomposed signal data. The time-domain waveforms are used widely for feature extraction. [ABSTRACT FROM AUTHOR]

This study aims to determine the effect of clearance and loading regarding to the displacement, distribution of contact loads and stiffness of spherical roller bearings at rest. The displacement formulation of the inner ring of the bearing was developed by defining the angle of inclination of the roller element to the axis of shaft. The comparison between exact calculations using the Matlab program and numerical modeling with MSC Marc for the displacement has an error value of less than 10%. Therefore, the displacement formulation of the inner ring of the bearing is used to calculate the exact distribution of contact load and stiffness of the spherical roller bearing and numerical modeling. The results revealed that the effect of clearance and loading on the displacement of the inner ring of the spherical roller bearing is directly proportional. The contact load of the bearing roller element is distributed over the part of the roller element that is in contact with its path, where the largest contact load occurs at the position of the roller element parallel to the axis of the shaft at rest. Meanwhile, bearing stiffness will decreases with increasing the value of clearance.

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Most studies on bearing stress analysis have considered single row rolling elements. In this study, the stress behavior of a spherical roller bearing with two rows of rolling elements is investigated. Photoelastic experimental hybrid method, is applied to investigate the interior and contact stresses of high-speed train bearings under combined axial and radial loads. The experimental results show that the bearing under investigation has the capability of sustaining high loads. The sharing of the loads between the two rows of rollers was found to contribute to excellent load bearing capabilities. It is also shown that the barrel-shaped roller has an influence on the stress concentrations and their distributions on the bearing races. At low radial and axial loads, the stresses on the races result from the bulging out section of the roller. As load is increased, the roller deforms and race stress occur at the ends of the roller, which now act like a punch. Only half of the bearing structure was found to be highly stressed. At position 3, the few isochromatic fringes on rollers and inner race shows that low stress concentrations occur on them. A comparison of the results from spherical roller bearing (SRB) and tapered roller bearing (TRB) showed that the stresses induced at the bearing races of the TRB bearing have higher magnitudes than those of SRB. This observation can be attributed to the two rows of rollers in SRB. High stress concentrations often lead to crack initiation and spall growth. Therefore, the low stresses on the SRB makes them more suitable for applications involving heavy loads. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the lack of effective test equipment and test methods, there was a lack of test research on the main shaft bearings of high-power wind turbines in the industry. Therefore, the influence of bearing load, operating temperature and operating speed on the bearing oil film thickness and life was studied. Firstly, the three-dimensional model of the main shaft test-bed was built and analyzed with Romax software. Based on GL2012 guide, the bearing load was calculated according to the maximum contact stress 1 650 MPa and bearing life 175 000 hours. Then, based on the calculated load and bearing rate speed, the effect of bearing load, temperature and speed on film thickness, contact stress and bearing life were analyzed. Finally, according to the film thickness and contact stress, the test load was determined. The results indicate that in order to avoid the edge stress concentration circumstance, bearing load must be less than 8 822 kN. In order to realize the elasto-hydrodynamic lubrication effect during test, the bearing temperature must be less than 65 ℃. When the bearing speed increases from 10.5 r/min to 30.6 r/min, the bearing minimum oil film thickness increases by 188%. According to the requirement of 175 000 hours fatigue life, when the bearing test speed is 12 r/min, the equivalent test is 2 984 hours under the load 8 500 kN, and the above results provide theoretical support for the actual bearing test. [ABSTRACT FROM AUTHOR]

The article deals with an optimization procedure of roller elements geometry with regard to durability of spherical roller bearings. The aim of the article is to examine the impact of change of the roller elements inner geometry on durability and reliability of spherical roller bearings; the contact strain along a spherical roller by means of the Finite Element Method at contact points of components of a spherical roller bearing by means of designed 3D parametric models. The most appropriate shape of roller elements inner geometry of a bearing from the standpoint of calculated durability was determined based on results of the contact analyses.

This article deals with an optimisation procedure of inner geometry of rolling elements designed for spherical roller bearings. A process of selection of the most appropriate solution to increase spherical roller bearing durability is understood under the term optimisation in this case. The aim of this article is to examine the impact of a change of inner geometry on the durability and reliability of spherical roller bearings regarding production technology and competitiveness. Contact strain along with a spherical roller by means of Finite Element Method (FEM) in contact points of components of a spherical roller bearing by means of designed 3D parametric models. The most appropriate shape of inner geometry of a bearing from the standpoint of calculated durability will be determined based on the results of analyses.

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Different from most bearing design guidelines, deformation of bearing rings and supporting structures usually influences the bearing performance significantly. Finite element analysis (FEA) can be used in bearing system design considering the structure deformation, but the contact region between rolling elements and raceways modeling is very complex and usually causes non-convergent problems. As to a spherical roller bearing (SRB), the model must also consider both its misalignment ability and roller contact stiffness. This paper presents a simplified SRB model considering the angular misalignment ability. In order to define the SRB roller raceway load deformation relationship, a lamina model is developed. And this simplified model is validated by solid roller model of a bearing sector. A wind turbine main bearing system is analyzed using the developed SRB model. Load distribution considering the system deformation and angular misalignment are discussed. With the help of fine meshed solid elements roller raceway contact model, the raceway contact pressure and subsurface stress distribution can also be obtained. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article deals with an optimization procedure of roller elements geometry with regard to durability of spherical roller bearings. The aim of the article is to examine the impact of change of the roller elements inner geometry on durability and reliability of spherical roller bearings; the contact strain along a spherical roller by means of the Finite Element Method at contact points of components of a spherical roller bearing by means of designed 3D parametric models. The most appropriate shape of roller elements inner geometry of a bearing from the standpoint of calculated durability was determined based on results of the contact analyses. [ABSTRACT FROM AUTHOR]

This article deals with an optimisation procedure of inner geometry of rolling elements designed for spherical roller bearings. A process of selection of the most appropriate solution to increase spherical roller bearing durability is understood under the term optimisation in this case. The aim of this article is to examine the impact of a change of inner geometry on the durability and reliability of spherical roller bearings regarding production technology and competitiveness. Contact strain along with a spherical roller by means of Finite Element Method (FEM) in contact points of components of a spherical roller bearing by means of designed 3D parametric models. The most appropriate shape of inner geometry of a bearing from the standpoint of calculated durability will be determined based on the results of analyses. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It has been observed that there are many studies focusing on the vibration properties of bearings caused by manufacturing errors, assembly related errors, out-of-balance rotor rotation, cage instability, etc. But there are fewer research studies on the effect of rotor's vibration on double-row rolling element bearings' mechanical properties. In this paper, a calculating method has been established for bearing's roller load and fatigue life when considering rotor's vibration. And this model is applied to study the main supporting bearing of the mixing drum of a certain type of concrete mixing truck with the consideration of the mixing drum's vibration. The effects of rotating speed, inclination angle, concrete liquid level, and rolling wheels' supporting position on the roller load and bearing's fatigue life are studied with a specific example with and without considering the mixing drum's vibration. Results show that with the increase in the rotating speed, the bearing roller's maximum load decreases, while the fatigue life of main supporting bearing increases. With the decrease of the concrete liquid level, there is increase in the inclination angle and the movement of rolling wheel from left to right, and the bearing roller's maximum load increases, while the fatigue life of main supporting bearing decreases. The changes of the mixing drum's inclination angle have tremendous effect on bearing's fatigue life, while the change in the rolling wheel's supporting position has little influence on the fatigue life of the main supporting bearing. When considering the mixing drum's vibration, the roller's maximum load is larger than that without considering mixing drum's vibration, while the fatigue life of the main supporting bearing is shorter than that without considering mixing drum's vibration. [ABSTRACT FROM AUTHOR]

The bearing race conformity is a design parameter that determines the degree of contact between rollers and races. This paper investigates the effect of race conformity on wear distribution in a railway spherical roller bearing under boundary lubricated condition in which contact behaves like a dry contact. The results showed that the traction/micro-slip distributions were substantially dependent on the level of conformity. The wear is found to be highly sensitive to the race conformity, with lower conformity resulting in lower wear. For example, 5.2% increase of conformity factor, a parameter that represents race conformity mathematically, reduces worn area by 52% in inner contact that is 60% in outer contact where conformity factor increase is 5.8%. This is mainly due to high value micro-slip being truncated at the edges as the traction distribution is compressed into the smaller contact patch. The bearings with ceramic rolling elements show lower wear than for steel rolling elements due to lower wear coefficient. The higher elastic modulus of ceramic causes the traction magnitude to be higher in the ceramic-steel case over the steel-steel case. Therefore, race conformity can be taken into consideration to optimize roller bearing wear life. • The influence of race conformity on the contact and wear characteristics are approached analytically. • The traction/micro-slip is analysed at different position of the loaded zone of a roller's revolution around the races. • An increase of race conformity by 5.2% increases wear area by 52%. • Wear distribution and traction/micro-slip are investigated for different material combinations. • Different material combinations show different level of wear and mainly due to friction/wear coefficients and elastic properties. Wear level changes with the material combination due to friction/wear coefficients. [ABSTRACT FROM AUTHOR]

This work presents a theoretical model to research the vibration due to surface waviness of spherical roller bearings (SRBs), taking account of the self-aligning feature and the external axial load. The surface waviness is described by cosinoidal functions. The self-aligning features, including the variation law of the self-aligning contact angle and the interaction with the external loads, are introduced into the non-Hertzian contact model. The nonlinear equations are solved by Runge-Kutta method and the proposed model is validated by comparing with the results of the published references. The results show more characteristic frequencies will be excited under the self-aligning operating condition, whereby the improved equations proposed in this paper are recommended to instead of the previous ones to predict characteristic frequencies of the waviness vibration in an SRB. In addition, these characteristic vibrations caused by waviness are obviously influenced by the magnitude and the direction of the self-aligning contact angle. A proper pretightening load should be chosen according to the self-aligning feature or else it will lead to hidden dangers. The radial clearance and the waviness amplitude can both highlight the effect of waviness. And the vibration caused by a larger radial clearance may be fiercer than the vibration due to waviness. [ABSTRACT FROM AUTHOR]

Adaptive local iterative filtering (ALIF) is a new signal decomposition method that uses the iterative filters strategy together with an adaptive and data-driven filter length selection to achieve the decomposition. The complexity of wind power generation systems means that the randomness and kinetic mutation behaviour of their vibration signals are demonstrated at different scales. Thus it is necessary to analyse the vibration signal across multiple scales. A method based on ALIF and singular value decomposition (SVD) was used for the fault diagnosis of a wind turbine roller bearing. The ALIF method is used to decompose the bearing vibration signal into several stable components. The components, which contain major fault information, are selected to build an initial feature vector matrix. The singular value of the matrix is computed as the feature vectors of each bearing fault. The feature vectors embody the characteristics of the vibration signal. The nearest neighbour algorithm is used as a classifier to identify faults in a roller bearing. Experimental data show that the proposed method can be used to identify roller bearing faults of a wind turbine. [ABSTRACT FROM AUTHOR]

This research presents a theoretical model to analyze the mechanical performance of spherical roller bearings, taking account of the angular and centroidal misalignments between the inner and outer rings. The angular misalignment can be improved by spherical roller bearings self-aligning feature to a certain degree. The interpolation method is used to determine the self-aligning contact angles of the different rollers. The centroidal misalignment is described by the angular and distance deviations. Non-Hertzian contact theory is applied to model and calculate the rollers load-distribution and total contact angles as well as the displacement of the inner ring. The loads of the rollers with the misalignments features and the external loads are included in the equilibrium equations, which is solved by Newton-Raphson method. This research shows spherical roller bearings self-aligning ability can balance the additional bending moment caused by the angular misalignment, which is at the cost of reducing its carrying capacity. But this carrying capacity will be improved to a certain degree by a proper axial load. It also illustrates that any kinds of centroidal misalignments are harmful for the service life of bearings. But the location of the misalignments can be roughly inferred by the external loads and the displacement of the inner ring, which is helpful for spherical roller bearings fault diagnose and elimination. [ABSTRACT FROM AUTHOR]

For the unsteady characteristics of a fault vibration signal from a wind turbine rolling bearing, a bearing fault diagnosis method based on adaptive local iterative filtering and approximate entropy is proposed. The adaptive local iterative filtering method is used to decompose original vibration signals into a finite number of stationary components. The components which comprise major fault information are selected for further analysis. The approximate entropy of the selected components is calculated as a fault feature value and input to a fault classifier. The classifier is based on the nearest neighbor algorithm. The vibration signals from a spherical roller bearing on a wind turbine in its normal state, with an outer race fault, an inner race fault and a roller fault are analyzed. The results show that the proposed method can accurately and efficiently identify the fault modes present in the rolling bearings of a wind turbine. [ABSTRACT FROM AUTHOR]

For the unsteady characteristics of a fault vibration signal of a wind turbine’s rolling bearing, a bearing fault diagnosis method based on variational mode decomposition of the energy distribution is proposed. Firstly, variational mode decomposition is used to decompose the original vibration signal into a finite number of stationary components. Then, some components which comprise the major fault information are selected for further analysis. When a rolling bearing fault occurs, the energy in different frequency bands of the vibration acceleration signals will change. Energy characteristic parameters can then be extracted from each component as the input parameters of the classifier, based on the K nearest neighbour algorithm. This can identify the type of fault in the rolling bearing. The vibration signals from a spherical roller bearing in its normal state, with an outer race fault, with an inner race fault and with a roller fault were analyzed. The results showed that the proposed method (variational mode decomposition is used as a pre-processor to extract the energy of each frequency band as the characteristic parameter) can identify the working state and fault type of rolling bearings in a wind turbine. [ABSTRACT FROM AUTHOR]

Tilt rotor supported by rolling bearings is often used in mechanical equipment. In the past, researches on dynamic performance of bearing-rotor were mainly carried out for horizontal rotor, but there is insufficient reported research on the tilting rotors. In this paper, the dynamic performance of a tilt rotor supported by spherical roller bearings is studied. Through the dynamics analysis of the rotor, a transfer matrix dynamics model for the tilt rotor is established. The stiffness and damping calculation model of spherical roller bearings is built. With a calculation example, the effects of tilting angles and some rotor structure parameters on the system’s dynamic performance are studied numerically. The results obtained show that with the increase in the tilt angle, the critical speed of the rotor decreases, and the amplitude increases in the vertical direction of the shaft. With the same tilting angle, the smaller the distance from the disc to the middle point of the rotating shaft, the larger the amplitude of the vibration mode and the amplitude difference compared to that of the rotor without inclination. The unbalanced response amplitude curves of the rotor distribute asymmetrically because of the rotor’s inclination. The bigger the inclination angle, the more obvious is the asymmetry distribution. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article aims to study the influence of two contact methods that may be used in bearing tilt analysis. This is of interest because an essential output in bearing analysis is the contact stress. The rating life of a bearing is a function of this parameter and bearing customers are usually interested in this criteria. The linear contact has long been studied using a simple Hertzian model. Time and errors are obviously opponent parameters: The Hertzian method is a fast solution but it cannot reach the accuracy of a detailed one that takes more time. In this article, a non-Hertzian method is presented in order to manage this analysis and the results are compared to those of the standard. [ABSTRACT FROM AUTHOR]

For the non-stationary characteristics of the vibration signal of wind turbine's roller bearing in fault condition, a bearing fault diagnosis method based on variational mode decomposition (VMD) and singular value decomposition (SVD) is proposed. The VMD method is used to decompose wind turbine's roller bearing's fault vibration signal into several components. These components are regard as initial feature vector matrix. The singular value decomposition of the matrix is done. The obtained singular value is used as the extracted bearing fault feature vectors. The probabilistic neural network is used as pattern recognition classifier to determine the working state and fault type of wind turbine roller bearings. The result of case study showed that the proposed method can effectively identify the working state and fault type of wind turbine roller bearings. [ABSTRACT FROM AUTHOR]

A mathematical model for accurately calculating heat generation rate in a grease-lubricated spherical roller bearing (SRB) is established in this paper by adopting the local heat source analysis approach, which involves in calculating heat generation rates of roller–raceway contact, cage and inner ring land contact, roller and cage pocket contact, and power loss of roller churning. Numerical calculating results show that the total heat generation rate of SRB increases as the inner ring rotating speed and radial load increase. The heat generated by roller–raceway contact is the dominant part in the total heat generation rate of the SRB. Some SRB geometrical parameters, such as diametral clearance and roller–raceway osculation, also have some effect on SRB heat generation rate. [ABSTRACT FROM AUTHOR]