Analysis Of Ball Bearings Research Articles

Application of Flores model considering variable recovery coefficient in dynamics analysis of ball bearings

PurposeThis paper aims to select an appropriate contact force model and apply it to the interaction model between the balls and the cage in the rolling bearings to describe the elastic–plastic collision phenomena between the two.Design/methodology/approachTaking the ball–disk collision mode as an example, several main contact force models were compared and analyzed through simulation and experiment. In addition, based on the consideration of yield strength of materials and initial collision velocity, a variable recovery coefficient model was proposed, and its validity and accuracy were verified by the ball–disk collision experiments. Then, respectively, the Flores model and the Hertz model were applied to the interaction between the balls and the cage, and the dynamics simulation results were compared.FindingsThe results indicate that the Flores model has good regression of recovery coefficient, indicating good applicability for both elastic and elastic–plastic contacts and can be applied to the contact collision situations of various materials. Under certain working conditions, there are significant differences in the dynamics results of rolling bearings simulated using the Flores model and Hertz model, respectively.Originality/valueThis paper applies the Flores model with variable recovery coefficients to the dynamics simulation analysis of ball bearings to solve the elastic–plastic collision problem between the rolling elements and the cage that cannot be reasonably handled by the Hertz model.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0138/

Dynamic performance analysis of ball bearings with multi-factor coupling excitation

Skidding behavior and unstable cage whirling of bearings are key factors limiting the service performance of a spindle-bearing system. This study proposes an improved dynamic model of ball bearings focusing on structure deformations and poor lubrication conditions. The ring deformations induced by the radial preload for the spindle-bearing-pedestal mechanical system are first discussed, and the asperity contact and starved lubrication conditions on the traction effect are further considered. Then, the cage flexibility induced by the centrifugal effect is determined by the lumped mass method, and cage clearance deformations are analyzed. On this basis, the dynamic equations are derived by investigating the motions and stress states among the bearing components, and the calculations are compared with experimental data to verify their accuracy and reliability. Finally, the regulatory mechanism of bearing skidding and cage motion stability from the perspective of bearing preload and structural parameters is revealed. The results show that although surface roughness and starved lubrication weaken the lubrication conditions of the ball-race, the traction effect is enhanced to reduce bearing skidding. Compared with the curvature radius of inner race, the groove diameter decreases the cage guiding effect, and ensures cage motion stability by suppressing the collision behavior of the ball-pocket. The system preload is more effective for improving the bearing service performance, which can optimize the collision force of the ball-pocket and increase the cage guiding effect.

Wear Failure Analysis of Ball Bearings with Artificial Pits for Gas Turbines

Wear Failure Analysis of Ball Bearings with Artificial Pits for Gas Turbines

A nonlinear dynamic approach for analyzing dynamic stiffness of ball bearings at different raceway diameters and guiding clearances

In this work, the stiffness matrix model is integrated into the dynamic model of ball bearings, in which the dynamic forces real-timely affect the stiffness calculation to form the dynamic stiffness, which is a novel solution for the dynamic performance analysis of ball bearings under different loads, assemblies and bearing structures. Then, the main influencing factors for the magnitude of bearing stiffness are analyzed. Next, the fluctuation mechanism of bearing stiffness is revealed. Subsequently, the effects of raceway diameters and guiding clearances on the dynamic stiffness of ball bearings are investigated. The obtained results suggest the ball diameter and the number of balls at various raceway diameters alter contact loads, contact angles, contact deformations and offset distances to change the bearing stiffness, and the combinations of inner and outer raceway diameters should be compromised to attain the favorable magnitude and fluctuation of bearing stiffness. Moreover, guiding clearance should be adjusted to achieve the desired trajectory of cage to degrade the fluctuation of bearing stiffness.

Wear failure analysis of ball bearings based on lubricating oil for gas turbine

PurposeBall bearings in gas turbine have played a critical role in supporting heavy radial loads but with higher failure rates and repair costs. Therefore, the purpose of this study is to introduce and study a method for their failure analysis with an actual industrial example to guarantee operation reliability and safety.Design/methodology/approachSpectrometric oil analysis was used as an early abnormal wear indicator, based on which emergent in-use oil replacement was carried out to reduce the wear rate. However, with wear deterioration, further wear failure investigation was conducted by LaserNet Fines and ferrography to detect the imminent wear failure. Finally, with the assistance of elemental analysis of the typical wear particles, the root cause and worn components were determined by scanning electronic microscope and energy-dispersive X-ray spectroscopy.FindingsThe results have shown that an extraneous source led to wear failure, which later caused overheat between the outer bearing ring and ball. It is in accordance with visual inspection of the disassembled engine.Originality/valueThis method has specified the occasion under which the suitable measurement can be taken. It can achieve the rapid wear condition assessment allowing for root cause and worn parts identification. In addition, wear rate reduction by change of oil can be efficient for most of the time to avoid premature disassemble, especially with the possibility of contamination. It has provided experience to address similar industry-level practical wear failure analysis problems.

Dynamic, thermal, and vibrational analysis of ball bearings with over-skidding behavior

The term “over-skidding” indicates that the cage rotational speed ratio exceeds the theoretical value as ball purely rolls on the raceway. Different from the skidding phenomenon that occurs in low-load and high-speed bearing, over-skidding usually occurs in large-size angular contact bearings, and it is still difficult to suppress under high load conditions. The main forms of damage to the raceway by over-skidding are spinning and gyro slip. To further explore the vibration characteristics and thermal effects of this phenomenon, a set of over-skidding tests of an angular contact bearing with a bore diameter of 220 mm were conducted on an industrial-size test bench. Through the experiment, the influence of axial load, rotational speed, and lubrication conditions on the occurrence of over-skidding were determined. Based on a previous dynamics model, the heat generation and thermal network models were integrated in the present study to predict the over-skidding and its thermal behavior. The model was validated in terms of the measured degree of over-skidding and temperature rise. The results showed that the degree of over-skidding reaches up to 12% of the theoretical value, and the friction power loss of the ball-pocket accounts for 30% of the total power loss. The analysis of the vibration signal showed a strong correlation between the bearing vibration characteristics and over-skidding behavior, thereby providing a way to indirectly measure the degree of over-skidding.

Influence of Ball Bearing Size on the Flight and Damage Characteristics of Blast-Driven Ball Bearings

This paper presents insights into the influence of ball size on the flight characteristics and damage of a ball bearing embedded in a rear detonated cylindrical charge. It includes results from a post-test damage analysis of ball bearings from previously reported experiments. Computational simulations using Ansys Autodyn were used to provide extra information about the velocity variation during flight and the damage sustained by the ball bearings during the blast event. The influence of bearing size (diameter and mass) was investigated using the validated simulation models to extend the dataset beyond the initial experimental work. The peak bearing velocity is influenced by the charge mass to ball bearing mass ratio and the aspect ratio of the charge. Larger ball bearings require extra momentum to accelerate them to higher velocities, but their higher surface area means a greater portion of the explosive charge is involved in transferring kinetic energy to the projectile. Tensile spalling was to be the major damage mechanism within the ball bearings. The charge aspect ratio also influenced the hydrostatic pressure propagation within the ball bearing itself, affecting the location and degree of internal cracking within the bearings. These findings will prove valuable to blast protection engineers considering the effects of embedded projectiles in improvised explosive devices.

Failure analysis of ball bearing in centrifugal pump using envelope and demodulation techniques

This case study delineates failure of bearing due to ingress of water through seals. In this study, failure of bearing was detected through vibration data acquisition followed by envelope and demodulation analyses. The results were confirmed through mathematical calculations with the help of MATLAB software. The observations confirmed that localized fault was induced in the bearing due to continuous ingress of the water from seals and insufficient lubrication helped corrosion proliferation. Further, root cause and failure analysis (RCFA) were conducted to identify the root causes of repeated premature failure in bearing. Based on recommendations of this study, improvisation in some of the existing mechanical configurations was done in the centrifugal pump to avoid any re-occurrence of such incidents. Vibration data from healthy and the faulty conditions of the bearings were taken and compared for drawing conclusions.

Correction to: Failure Analysis of Ball Bearing of Conveyor: Overusage

In the original version of the article, Prabhash Gokarn’s last name was misspelled. The original version of the article has been corrected.

Failure Analysis of Ball Bearing of Conveyor: Overusage

Rolling bearings are machine elements found in a wide field of applications. They are reliable even under the toughest conditions. When bearings fail to meet their expected life, the consequences are increased down time, loss of revenue and missed delivery. Hence, it is important to know the bearing theoretical fatigue life. However, unfortunately, it sometimes happens that a bearing does not attain its calculated rating life. There may be many reasons for this—heavier loading than has been anticipated, inadequate or unsuitable lubrication, careless handling, ineffective sealing, improper mounting and improper clearance. This article describes the failure of a conveyor bearing in rolling contact fatigue. The investigation consists of visual observation, chemical analysis, characterization of microstructures using optical microscopes and hardness test. The study also calculates the bearing fatigue life (L10) under these operating conditions. Surface-initiated rolling contact fatigue, leading to spalling, is a life-limiting failure mode in bearings. Ferrography test, discussed in this paper, indicates fatigue spalling. Analysis suggested that the conveyor bearing failed near its calculated fatigue life and the failure occurred in rolling contact fatigue. Periodic schedule, after calculating L10 life, for changing the bearing and scheduled ferrography checks can eliminate this type of unplanned breakdown.

Analysis of high speed bearing based on virtual rods model

The traditional high-speed ball bearing analysis is based on the quasi-static model proposed by Jones-Harris (J-H). This study gives another bearing analysis model based on the relative position of the ball center and the centers of curvature of the raceway grooves, described by the virtual rods. Specifically, the load and deformation of the virtual rods are determined according to the principle of force transmissibility, the translation theorem of a force, and elastic-contact deformation between steel ball bearings and raceway grooves. And the iterative variables such as the axial, radial and angular deformations are gradually introduced into the calculation model to solve the force and kinematic parameters under pure axial load, bidirectional and tri-directional combined loads. The correctness of the virtual rods model is verified by the contact angle for axial and bidirectional load. The influence of gyroscopic moment and raceway grooves control parameter on the actual contact angle under tridirectional loading conditions are calculated and analyzed respectively. The proposed model uses fewer equations and lower-dimension parameters than those used by the traditional highspeed ball bearing analysis method, improves the solution rate of the equations.

Fatigue Life Analysis of Ball Bearings and a Shaft System Considering the Combined Bearing Preload and Angular Misalignment

Bearing preload significantly affects the running performance of a shaft-bearing system including the fatigue life, wear, and stiffness. Due to the mounting error, the bearing rings are often angularly misaligned. The effects of the combined bearing preload and angular misalignment on the fatigue life of ball bearings and a shaft-bearing system are analyzed in this paper. The contact force distribution of angular contact ball bearings in the shaft-bearing system is investigated based on the system model. The system model includes the bearing model, and the shaft model is verified by comparing with the manufacturer’s manual and the results from other theoretical models, with the difference between the results from the present bearing model and manufacturer manual within 3%. The global optimization method is used to replace the Newton–Raphson algorithm to solve the ball elements’ displacements and friction coefficients, which improves the computation efficiency of the system model. The fatigue life of each bearing is evaluated with the consideration of the two preload methods and two angular misalignment cases. The fatigue life results show that the system life at the optimal angular misalignment is more than 1.5 times that without angular misalignment at the low preload value, and this ratio decreases as the preload value increases. The optimal angular misalignment of both the shaft-bearing system and the misaligned bearing is not always consistent, which depends on the preload value and bearing life. Both the constant-displacement preload and constant-force preload do not cause a significant difference in the highest system life. The different misaligned bearings can lead to different highest system lives as the preload value is low.

Influence of bearing raceway surface topography on the level of generated vibration as an example of operational heredity

In this paper, an influence of surface topography of ball rolling bearing raceways of the vibration values has been examined. Experiments have been preferment using series of bearing types 6304. Surface topography of bearing raceways has been measured using a stylus profilometer Talysurf PGI 1230. The 2D and 3D roughness and waviness parameters have been analyzed. The vibration measurements of ball rolling bearings have been carried out using a measuring device ―Anderonmeter‖. The concept of technological heredity and operational (exploitation) heredity in the aspect of production and operation of rolling bearings has been presented. Based on experimental study, an operation heredity analysis of ball bearings has been carried out. It has shown that the condition of surface texture of rolling bearing raceways directly affects the values of vibration generated by bearing units.

Theoretical and experimental approach to ball bearing frictional characteristics compared with cryogenic friction model and dry friction model

Abstract In previous studies on cryogenic ball bearings, a friction model of solid lubrication characteristics was employed with the assumption that the low dynamic viscosity of cryogenic fluids is negligible. A traction curve was then created using this dry friction model, with curve fitting being performed using a traction coefficient derived from the results of a ball-on-disk experiment with corresponding solid lubricant. However, the behavior prediction had many limitations, because the fluid characteristics in the cryogenic environment and the friction characteristics of the bearing components were not reflected. This study attempts to improve the reliability of cryogenic ball bearing dynamic analysis by proposing a hydrodynamic friction model considering the hydrodynamic effect of cryogenic fluids. A ball-on-disk experiment is conducted by simulating (1) ball-cage friction, (2) ball-inner/outer race friction, and (3) cage-inner/outer race friction characteristics. Hence, it is found that uncertainty factors causing traction coefficient fluctuation exist in certain device sections, reflecting the effect on the wear surface of friction and the hydrodynamic effect of the shear stress of the cryogenic fluid (liquid nitrogen). A dynamic experiment and cryogenic ball bearing analysis using the model considering the hydrodynamic effect are conducted and compared. From the ball bearing dynamic behavior analysis, the hydrodynamic friction model is found to predict a bearing friction coefficient that is closer to the actual value than the dry friction model. When the proposed model is applied to bearing dynamic behavior, it is possible to predict the cryogenic-bearing friction coefficient with 50% higher accuracy than the existing method.

Parametric vibration Analysis of Rotating Machinery

In rotating machinery, the most extensively used element is the rolling bearing element around 90%. Based on the size speed and lubrication technique the classification of the bearing is done. The premature failure of this rolling bearing element is most common and the factors are countless. A very small percentage of these bearings are able to work for full life span provided with operating condition subjected. For all the types of defects in bearings can be studied and characterized by vibration spectrums. In the different types of measurement technique for detecting, the defects in the bearings vibration signature play prominent role. In this paper, a new parametric Analysis of ball bearing in rotating machinery with respect to vibration spectrum is carried out for that an experimental test rig is designed considering the outer race defect in the ball bearing. For these the vibration spectrum obtained for the test ball bearing based on the time and frequency domain is parametrically studied under radial load and constant speed. And these parametric data obtained from the vibration signatures measured for the different time span, is used as statistics for accurate assessment of bearing failure with respect to time and ascertain the exact defect locations in outer race of the bearings.

Numerical Study of Cage Dynamics Focused on Hydrodynamic Effects of Guidance Land Clearances for Different Ball-Pocket Clearances in Cryogenic Environments

This study presents the dynamic motion of a ball bearing cage submerged in a cryogenic fluid under high-speed conditions. The dynamic motion of the cage has been studied as a function of the race land-cage and ball-cage pocket clearances for different inner race rotation speeds under light load conditions. In addition, this study conducted computational fluid dynamics (CFD) analysis using commercial software to analyze the fluid dynamic forces on the cage. The hydraulic force obtained from the CFD analysis was coded in commercial ball bearing analysis software as a function of the eccentricity ratio and rotation speed of the cage. Finally, the dynamic motion of the ball bearing cage considering the effects of fluid dynamic forces has been studied. The results include the cage whirling amplitude, fluctuation of cage whirling speed, and cage wear for various cage clearances and rotation speeds. The cage whirling amplitude decreases as the outer guidance clearance decreases, and it decreases as the rotation speed increases up to 11,000 rpm because of the increasing hydrodynamic force of the liquid nitrogen (LN2). However, the probability density function curves indicate that an increase in the rotor speed increases the standard deviation in the cage whirling frequency. The wear loss of the cage was greatest for the largest race land-cage and the smallest ball-cage pocket clearances. Consequently, the analysis results for various operating conditions (inner race rotation speeds, cage clearances, traction coefficients, etc.) are in good agreement with the reference results.

High frequency vibration analysis of ball bearings under radial loads

The paper investigates the role of radial load and rotating speed on the high frequency vibration of a deep groove ball bearing. Firstly, a bearing dynamic model with 6-DOF balls was established, considering the interactions between balls, races and the cage. The dynamic model was solved by fourth order varying steps Runge-Kutta integration. The frequency spectrums of dynamic response of races were analyzed with yule-walker and FFT. Secondly, a verification experiment was done with different radial loads and speeds. Finally, compared with the numerical and experimental results, the similar trend of the high frequency vibration was emerged. Higher vibration frequencies result with increasing bearing load; higher vibration amplitude cause by more quickly rotating speed. That is because the nature frequencies of the races are excited by the contact and shock between balls and races when balls leave from the non-load to the load zone. The frequency spectrums were also affected by the interaction between the balls and cage.

An Analytical Model of Four-Point Contact Rolling Element Ball Bearings

The purpose of this work is to establish an analytical model and standard way to predict the performance characteristics of a four-point contact, or gothic arch type, rolling element ball bearing. Classical rolling element bearing theory, as developed by Jones, has been extended to include the complex kinematics of the four-point contact bearing; thereby providing complete elementwise attitude and internal load distribution of the bearing under operating conditions. Standard performance parameters, such as element contact stresses, contact angles, inner ring deflections, nonlinear stiffness's, torque, and L10 life, are solved explicitly via standard Newton–Raphson techniques. Race control theory is replaced with a minimum energy state theory to allow both spin and slip to occur at the ball-to-raceway contact. The developed four-point model was programed within the orbis software program. Various test cases are analyzed and key analytical results are compared with the Jones four-point contact ball bearing analysis program, the Wind Turbine Design Guideline, DG03, and traditional two-point (angular contact) analysis codes. Model results for the internal distribution of ball loads and contact angles match the Jones program extremely well for all cases considered. Some differences are found with the DG03 analysis methods, and it is found that modeling a four-point contact bearing by overlaying two opposed angular contact bearings can result in gross errors.

Failure Analysis of Ball-Bearing of Turbo-Pump Used in Liquid Rocket Engine

Rolling contact bearings often referred as antifriction bearings are found in many applications where rotating components are involved. Extreme operating conditions, counterfeit or inferior quality bearings, inadequate lubrication, etc often lead to bearing failures. Each rolling contact bearing failure leaves traces of evidences on what caused its failure. Failure analysis of one such bearing is the subject of this paper.One of the engine ground tests was aborted due to the failure of a self-aligning deep groove ball bearing used in turbo-pump of a liquid rocket engine. Series of engine ground tests are conducted as a part of injector acceptance for a liquid rocket engine. The bearing failure occurred in the seventh engine test of one of such series of ground tests. The bearing mentioned here is made of SAE 52100 steel. Post-test hardware inspection revealed that the bearing and the dynamic seals on either side of the bearing are in failed condition. Inner race of bearing was found blackish in appearance with indentation and corrosion marks. Localized black spots were observed in outer race. Bearing balls were found in deformed condition. The paper highlights the failure analysis of the bearing, root cause of the bearing failure and recommendations to avoid such failures.

적외선열화상을 이용한 베어링 실시간 손상검출 상태감시의 전산수치해석 비교

Abstract Since real-time monitoring systems, such as early fault detection, have been very important, an infraredthermography technique was proposed as a new diagnosis method. This study focused on damage detection andtemperature characteristic analysis of ball bearings using the non-destructive, infrared thermography method. In thispaper, for the reliability assessment, infrared experimental data were compared with finite element analysis (FEA)results from ANSYS. In this investigation, the temperature characteristics of ball bearing were analyzed undervarious loading conditions. Finally, it was confirmed that the infrared thermography technique was useful for thereal-time detection of damage to bearings. Keywords: Condition Monitoring, Infrared Thermography, Ball Bearing, Damage Detection, FEA (Finite ElementAnalysis)[Received: May 12, 2015, Revised: June 16, 2015, Accepted: June 17, 2015] *전북대학교공과대학기계시스템공학부, ** ,공주대학교 공과대학 기계자동차공학부 Corresponding Author: Div. of Mechanical and AutomotiveEngineering, Kongju National University, Cheonan, Chungnam, 331-717, Korea (E-mail: kwt@kongju.ac.kr)