Bearing Fatigue Life Research Articles

Bi-level optimization and integrated multiple-criteria decision making under uncertainty for structural design of insulated bearings

To address the premature failure of insulated bearings, this article proposes a design method for the structure of bearings to prolong their service life. First, a bi-level optimization model is established to determine the structural parameters of bearings considering their insulating and mechanical properties. Upper-level problems include bearing voltage ratio, porosity of insulating coatings, minimum thickness of oil film and Hertz contact area. Lower-level problems include fatigue life of bearings and adhesion of insulating coatings. Second, a non-dominated sorting genetic algorithm-III based on space decomposition and penalty-based boundary intersection (NSGA-III-SD-PBI) is designed to solve the optimization model. Third, the integrated multiple-criteria decision-making (MCDM) using the fuzzy best–worst method (BWM) and fuzzy technique for order preference by similarity to an ideal solution (TOPSIS) is developed to determine the best structural parameters of bearings. A case study demonstrates the effectiveness and superiority of the proposed method, with fatigue life increased by 20%.

Effect of stick and slip zones on fatigue life of a slewing ball bearing

Prediction of fatigue life of slewing ball bearings is challenging due to the influence of large deformations and adverse lubrication conditions. The present study presents an elegant simulation model that considers the flexibility of the supporting elements of the slewing bearing along with stick/slip zones at the raceway-ball contact interface. Using the stresses predicted by the simulation model, relative fatigue life using stick/slip condition versus no-friction condition is computed. A sensitivity study of the ball contact force, ball contact angle, coefficient of friction and raceway conformity is also performed. The present study also evaluates the results in comparison with full-sliding assumptions. The final results show that the stick/slip zone determination at the contact interface is beneficial for accurate determination of fatigue life of slewing bearings.

Study on the Friction Characteristics and Fatigue Life of Carbonitriding-Treated Needle Bearings

Being a key component of the transmission system, the needle bearing’s performance and service life affects the overall service life of mechanical equipment. This study takes needle bearings composed of AISI 52100 steel as the research object and studies the effect of carbonitriding surface strengthening treatment on the bearing friction, wear, and fatigue life. The carbon and nitrogen co-infiltration surface-strengthening method was employed to prepare cylindrical and disc samples. The surface hardness, residual austenite content, microscopic morphology and organization composition, coefficient of friction, and wear scar were studied to analyze the effect on the wear performance of the material. The bearing fatigue wear comparison test was conducted on a test bench to compare the actual fatigue life and surface damage of the needle bearing through conventional martensitic quenching heat treatment and carbonitriding treatment. The results demonstrate that the carbonitriding strengthening method enhances the toughness of the material while improving its surface hardness. It also improves the wear resistance of the needle roller bearings, and the fatigue life of the bearings is significantly improved. In conclusion, carbon and nitrogen co-infiltration treatment is a strengthening method that effectively extends the service life of needle roller bearings, indicating its high practical value.

Enhancing longitudinal performance in railway suspension bridges through an integrated cable restrainer system

Longitudinal motion is a crucial factor affecting the fatigue life of expansion joints, bearings, dampers and short suspenders in suspension bridges. Traditional control methods relying solely on fluid viscous dampers often magnify the relative displacement between the main cable and the girder (hereafter referred to as relative displacement), leading to fatigue problems in the short suspenders. To overcome these shortcomings, an Integrated Cable Restrainer System is proposed. Firstly, a suspension bridge is described, and both a Refined Finite Element Model (RFEM) and a Simplified Finite Element Model (SFEM) are developed and compared. Subsequently, the effectiveness of three cable measures in reducing the longitudinal motion response and the relative displacement of the bridge is evaluated: the cable central buckle (Type I, connecting the main cable and the girder), the inclined control cable (Type II, controlling the main cable) and the longitudinal control cable (Type III, controlling the girder). Finally, an Integrated Cable Restrainer System integrating type I to type III measures is proposed and compared with FVDs, and its control benefits on train and seismic induced vibration are discussed. The results indicate that the SFEM has a higher calculation efficiency while maintaining comparable accuracy. All three types of cable restrainers are effective in controlling the longitudinal movement of the girder end, although type III increases the relative displacement. The Integrated Cable Restrainer System not only effectively controls longitudinal motion (induced by trains and seismic events) but also reduces the relative displacement at the short suspender positions. By employing the Integrated Cable Restrainer System combined with dampers for controlling longitudinal motion, the undesirable effects associated with damper usage can be effectively mitigated. This research serves as a valuable reference for bridge design and longitudinal motion control in suspension bridges. Data AvailabilitySome or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.

Contact force and pressure analysis of the three-row roller pitch bearing in a large-scale wind turbine

Pitch bearings are the key components of wind turbines (WTs). The reliability of pitch bearings affects the electric energy output efficiency of WTs. Due to its large loading ability, constant contact angle and high stiffness, the three-row roller slewing bearing (TRSB) is becoming a more attractive choice as a pitch bearing, especially in large-scale WTs. The contact force and pressure distributions significantly affect the fatigue life of a three-row roller pitch bearing (TRPB). Therefore, it is essential to propose a precise calculation method for the contact force and pressure. The present work establishes a quasi-static five degree-of-freedom (DOF) mathematical model for TRPBs, in which the bearing under general loading conditions is considered. The influences of combined external forces, overturning moments and inner ring misalignment angle on the contact force and pressure distributions of TRPBs are comprehensively investigated. According to the analysis results, the overturning moment and axial force can significantly affect the number of load-carrying rollers in each row. Furthermore, a slight variation of the inner ring angular misalignment has a significant effect on the contact force and pressure of TRPBs. Finally, it is more prone to pressure concentration in the non-crowned roller than that in the crowned roller, especially in the case of the inner ring with a misalignment angle. Since the high calculation efficiency and accuracy, the proposed method has remarkable potential applications in the fatigue life prediction and design of TRPBs.

Optimizing Stainless Steel Bearings: Enhancement of Stainless Steel Bearing Fatigue Life by Low-Temperature Forming

A proposed low-temperature forging method is presented to enhance stainless steel bearings by creating a martensitic subsurface layer, significantly boosting bearing fatigue life due to increased surface hardness. This technique induces beneficial residual stresses, particularly in axial bearings, streamlining their construction and improving machine elements. Challenges persist, especially with radial bearings, but simplicity in axial bearing forging promotes compact, resource-efficient facility construction. Future research will focus on applying this technique to axial bearing washers, potentially replicating success in other bearing components. Despite the energy expenditure on cooling during forging, the substantial increase in bearing fatigue life offsets this, enhancing overall durability and reliability of critical machine components. Integration of this forging technique into bearing fabrication appears seamless, offering a promising trade-off between energy use and enhanced performance.

An optimization design method of asymmetric wheel bearing with equal friction torque and equal fatigue life in two rows

Aiming at the problem of asymmetric wheel bearings with inconsistent friction torque and service life of the left and right rows, this paper proposed a different optimization design method for asymmetric wheel bearings. Firstly, the calculation model of friction torque and fatigue life of asymmetric wheel bearings is established based on the proposed quasi-statics, and the model's accuracy is verified. Furthermore, combined with the Cooperative Equilibrium Point Method, the optimization method of equal friction and equal life for the left and right rows, that is, CEPM-NSGAII, is proposed, which takes the ratio of friction torque and the ratio of fatigue life for the left and right rows as the objective function, and optimizes the structural parameters of the left and right rows such as the rolling element diameters, the pitch circle diameters, and the number of rolling elements, and so on. After optimization, the friction torque ratio and fatigue life ratio of the left and right rows tend to be close to 1, which considerably improves the performance imbalance between the left and right rows of the bearings, meanwhile prolongs the fatigue life of the bearings and reduces the friction torque of the bearings. In addition, the superiority and reliability of the CEPM-NSGAII optimization method are verified by comparison.

Fatigue life and fatigue reliability mechanism of ball bearings

AbstractAs the main supporting parts of rotating machinery, the fatigue life and fatigue reliability of ball bearings directly affect the accuracy, stability and reliability of equipment. Based on the quasi-static model of bearing and the fatigue life theory, this paper analyzes the effect of the external loads on the mechanical properties and fatigue life of bearing, and studies the action mechanism of bearing working conditions and other parameters. In addition, based on the stress–strength model and the fatigue life model of bearing, the fatigue reliability and sensitivity of bearings are analyzed by means of perturbation method, Edgeworth series and fourth moment technique, and the correctness is verified by the Monte Carlo simulation. Results have important theoretical and practical value, and can provide theoretical support for the research of reliability optimization design, fault mechanism and fault diagnosis method of ball bearings.

Correction to: Fatigue life and fatigue reliability mechanism of ball bearings

Correction to: Fatigue life and fatigue reliability mechanism of ball bearings

Fatigue Life Analysis of Remanufactured Radial Rolling Bearing with the Replaced Loading Zone

The replacement of the loading zone is not considered in the active calculation method on fatigue life of remanufactured bearings. In practical application, when the radial bearings are reinstalled after remanufacturing, it is required to replace the loading zone, which results in a large deviation between the calculated fatigue life according to the active calculation method and the actual life. In this paper, the fatigue life factors of radial bearings with different remanufacturing levels are calculated according to the actual application condition. The results of case studies show that with the improvement of the remanufacturing level, regardless of whether the loading zone is replaced or not, the remanufacturing bearing life factor is gradually increased and the maximum can reach 1. Considering the replacement of the loading zone, the life factors of remanufactured bearings with different fixed rings are also very different, among which the remanufacturing deviation of fixed outer-ring level II is the largest, reaching 11.3%. However, with the increase of the remanufacturing level, the deviation decreases gradually. The life factors by the method presented in this paper of remanufactured radial bearings with the replaced loading zone are significantly higher than those of the active calculation method. The research results of this paper provides a more accurate calculation scheme for the fatigue life of remanufactured radial rolling bearings, which is a supplement to the active calculation method and has important practical significance for the practice of bearing remanufacturing engineering.

Design of Flexible Bearing with Larger Inner Diameter

The flexible bearing is the kernel component of the cam wave generator. In precision transmission applications such as miniature robot joints, flexible bearings are required to have a smaller mass, lower moment of inertia, and larger inner diameter. Based on the theory of conventional rolling bearing, and by considering the working characteristics of flexible bearing for harmonic drive, this paper studies the influence law of structural parameters on the fatigue life of the flexible bearing; achieves a technical approach for expanding the bore size of the standard flexible bearing; and deduces the theoretical formulas applicable to the design of the flexible bearing. The new formula is utilized to improve the design parameters of the flexible bearing. The novel design with smaller diameter and more numbers of rolling elements can meet the above performance requirements compared to the conventional flexible bearing. Under the same conditions of radial deformation and materials used, finite element analysis results show that the maximum equivalent stress in the improved flexible bearing is smaller and that the novel design can meet the strength requirements of the harmonic drive.

Study on Grinding-Affected Layer of Outer-Ring Inner Raceway of Tapered Roller Bearing.

In the grinding of bearing raceways, the coupling effect between grinding force and heat in the contact area between the grinding wheel and the workpiece causes changes in the material structure and mechanical properties of the raceway surface layer, which can lead to the formation of a grinding-affected layer. The grinding-affected layer has a significant impact on the service performance and fatigue life of bearings. In order to improve the ground surface quality of the outer-ring inner raceway of tapered roller bearings and optimize the processing parameters, this paper presents a study on the grinding-affected layer. A finite element simulation model for grinding the outer-ring inner raceway of the tapered roller bearing was established. The grinding temperature field was simulated to predict the affected-layer thickness during raceway grinding. The correctness of the model was verified through grinding experiments using the current industrial process parameters of bearing raceway grinding. The research results indicate that the highest grinding temperature of the outer-ring inner raceway of the tapered roller bearing is located near the center of the grinding arc area on the thin end edge. As the workpiece speed and grinding depth decrease, the highest grinding temperature decreases, and the dark layer thickness of the grinding-affected layer decreases or even does not occur. The research results can provide theoretical guidance and experimental reference for grinding the raceway of tapered roller bearings.

Optimization of Autoclave Reactors to Improve Bearing Life Using the Taguchi Method and the Response Surface Methodology

Plastic pervasiveness in daily life has increased in tandem with population growth. Ethylene–vinyl acetate (EVA) is emerging as a popular compound for manufacturing plastic, which is obtained from ethylene and vinyl acetate synthesis. EVA is produced using autoclave reactors, which often encounter bearing damage under specific operating conditions. This research aims to optimize the parameters in autoclave reactors to enhance bearing life. The study focuses on two crucial factors: the number of impellers and the temperature, with bearing life as the response variable. Simulations using finite-element analysis were conducted to obtain the fatigue life of bearings and validated using real-time company data stating the damage of bearings within 80 days. The optimization process employed the Taguchi method (TM) and the response surface methodology (RSM). A comparison of these techniques revealed that temperature had the most significant influence on the response. Interestingly, both methods yielded the same optimal parameters: seven impellers and a temperature of 150 °C. The simulation results using these optimized parameters demonstrated a noteworthy 3.095% increase in bearing life compared to the initial design. The RSM outperformed the Taguchi method in accurately predicting response values with minimum prediction error under optimal conditions.

Development and Perspectives of Bearing Life Testers

Background:: Bearings are a kind of precision mechanical basic parts that are widely used in aerospace, automobile, home appliances and industrial fields. At the same time, bearings are also one of the most important wear parts in mechanical equipment. The research and analysis of bearing life are of great significance as they directly affect the efficiency and safety of the equipment. Objective:: By analyzing and discussing the patents on bearing life testing devices, some valuable conclusions have been drawn, and the development direction of bearing life research and bearing testing devices is speculated. Methods:: Various bearing life testing devices, such as life testing machines, performance testing machines and simulation testing machines, are observed, and the influence of bearing life testing devices on bearing quality assessment and product development is analyzed. The patents about the bearing life testing device are investigated in conjunction with the bearing life data signal acquisition method. Results:: The analysis of bearing life detection devices in bearing fatigue life and performance failure in the bearing failure detection collection method primarily uses vibration detection method, while bearing life detection devices primarily focus on structural innovation and detection method innovation to improve the accuracy of bearing detection. Conclusion:: The development of the bearing detection device and the advancement of test software, multi-species, small batch, high precision, multiple control, group control, simulation of working conditions, and special development work in tandem to address technical issues and improve bearing detection device functionality.

Effect of different roller end-flange constructions on the fatigue life of the cylindrical roller bearings: A novel flange deformation formula

This paper performs the fatigue life analysis of the radial Cylindrical Roller Bearings (CRBs) with consideration of various roller end-flange shapes such as toroidal-toroidal, spherical-toroidal, and spherical-conical. A novel formula for each flange contact deformation in cylindrical roller bearing with different roller end-flange geometry including toroidal geometry is developed. Inner ring misalignment angle and radial deflection results obtained from the present study are verified with numerical and experimental results from the literature. The results approach to that of literature when the flange is changed from toroidal geometry to conical geometry. Using formulas developed in the present study, the effect of various roller end-flange geometries on the bearing life is investigated for different external loadings. It is observed that the bearing life increases when the roller end and flange are changed to toroidal geometry.

A new solving method for ball bearing dynamics model based on optimization with nonlinear constraints: Contact angles as iterative variables

Bearing dynamics model is the premise for bearing vibration analysis and fault diagnostics. This paper proposed a novel modeling and solving method for angular contact ball bearing dynamics. It transformed the problem of solving nonlinear model equations into an optimization issue with equality constraints by choosing contact angles rather than deformations as the iteration variables. Additionally, to accelerate the solving convergence and reduce dependence on the initial values, a polynomial model was adopted to approximate and define the contact angle initials by analyzing their value distribution characteristics at different ball positions. Furthermore, a genetic algorithm was applied to reset the initial values at every iteration to speed up the solving process and improve the global search capability. Simulations under various conditions were used to validate the proposed method and compared with the traditional Newton–Raphson solving method. The influence of contact angles on bearing fatigue life was also analyzed. Results showed that the accuracy, efficiency, and dependence on the initial values were thoroughly improved.

Fatigue life prediction of rolling bearings based on damage accumulation considering residual stresses

The determination of the fatigue life of rolling bearings is recommended to be conducted using the standard calculation models defined in ISO 281. These models yield reliable results for rotating applications. The standard models are continuously refined to align with advancements in bearing production processes and material improvements. However, when dealing with rolling bearings exposed to complex load conditions including oscillatory movements, as seen in rotor blade bearings in wind turbines, a validated calculation model has yet to be established. In the domain of structural mechanics, fatigue life evaluation for steel components is based on S-N curves. Variable operational loads are treated as load collective, and the load cycle to failure N under given operational conditions is determined through the application of the linear damage rule. This paper introduces a novel model that integrates the linear damage rule with established conventional bearing theories. Within one internal stress cycle, all rolling contacts are regarded as an internal load collective. To evaluate the internal load collective, the stress state at each rolling contact is assessed based on the S-N curve determined in alternating torsional loads. The core rationale behind the selection of an S-N curve lies in the stress criterion τo based on Lundberg-Palmgren theory, which is incorporated in the new model. This paper includes a comprehensive step-by-step procedure for applying the new model, utilizing the cylindrical roller bearing NU 1006 as a reference. The results of this study indicate a favorable agreement between the fatigue life obtained using the new model and those determined according to ISO 281. Furthermore, a new approach is introduced to analytically account for residual stress - es when measured values are available. In this study, by applying this new approach, the results were observed to be in close agreement with the test results. Based on this investigation, it can be confirmed that the new model has the potential to provide reliable results without necessitating the bearing life exponent as well as the correction factors often required in conventional calculation models.

Optimized selection of fluid lubricant for cylindrical roller bearings under elastohydrodynamic lubrication

Roller bearings are widely used in machinery. Keeping the contact surfaces of bearings properly lubricated strongly mitigates wear effects, improving bearing fatigue life. Therefore, systematically selecting the lubricant fluid that satisfies bearing operation conditions allows the lubricating layer to be able to carry the applied load, the operating temperature, and the roughness on contact. The nonlinear constrained optimization method is used for lubricant selection, seeking to find the fluid that best fits the bearing operation conditions. Roller bearing lubrication is characteristically elastohydrodynamic (EHL); namely, the Hertz theory describes the load applied on the contacts of a cylindrical roller bearing, and the Stribeck condition classifies the tribological condition of the surfaces in contact. This work concludes that roughness and speed are the most important parameters to consider when choosing a fluid lubricant.

Structural optimization of pitch bearings for offshore wind turbines

Pitch bearings are key components for the pitch system of wind turbines, and their reliability is closely associated with normal operation of wind turbines. In this paper, to solve the low efficiency problem of the GH Bladed and MATLAB software in design and analysis due to its operation in a single-user, stand-alone and single-key mode, GH bladed and MATLAB were combined based on Python for the integrated load spectrum calculation of pitch bearings through the full life cycle. Based on theories of contact strength analysis and fatigue life, finite element analysis and sub-modelling refinement techniques are established to investigate the relation between structural parameters and raceway stress of the bearings. Based on the Artificial Fish Swarm Algorithm (AFSA), the structural parameters are optimized to minimize the maximum contact stress on the bearing raceways and maximize the fatigue life of the bearings. The results show that the maximum contact load and the maximum contact stress on the pitch bearing raceways are significantly reduced and the bearing fatigue life is notably increased by 8.7%. The method proposed in the present study applies not only to pitch bearings, but also to other large four-point contact ball bearings.

Comparison of fatigue life behavior between deep groove radial ball bearings possessing conventional and micro-grooved outer races operating under dry condition

A comparative study on fatigue life of deep groove radial ball bearings possessing conventional and micro-grooved outer races by experimental investigation is discussed in this paper. This research has been carried out to explore and understand the fatigue life of a micro-grooved ball bearing (MGB) with a circumferential micro-groove on outer race by conducting long duration tests under dry condition (i.e. wiping out the applied grease from the races by using tissue paper and lint free cloth) and compare the results with same size SKF BB1B 420206 conventional bearing (CB) at the identical operating parameters. Frictional torque (FT), bulk temperature, and overall vibration level of the test bearings (CB and MGB) at the maximum load zone have been measured at 800 N ( pH = 1.7 GPa) radial load and 1800 rpm (4.2 m/s) for the entire duration (7.8 million revolutions) of the experiments. Comparison of the surface conditions of the bearing components by means of the captured scanning electron microscope (SEM) images, roundness and deviation in profile of the races measured by co-ordinate measuring machine (CMM), and photographs captured before and after the experiment indicates lesser damage of the MGB components as compared to the conventional cases. Moreover, the initiation of fatigue failure in CBs is faster as compared to the MGBs for the same test condition, indicating longer bearing life in MGBs as compared to the CBs.