Design Of Bearing System Research Articles

A simplified spherical roller bearing model and its application in the wind turbine main bearing system finite element modeling

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.

Research on the Optimal Design Approach of the Surface Texture for Journal Bearings

Aiming to improve the comprehensive performance of the journal bearing system, this paper presents a multi-objective adaptive scale texture optimization design approach. A mixed lubrication model for the textured journal bearing system is established by considering the effects of cavitation and roughness. The geometrical parameters of the textures were co-optimized using a multi-objective grey wolf optimizer to obtain the optimal texture schemes that are suitable for different operating conditions. Through this approach, the influences of different texture schemes under transient operating conditions can be investigated. According to the results, it was found that different texture schemes result in different friction reduction effects. Proper surface texture is beneficial in increasing the minimum oil film thickness and reducing the possibility of asperity contact. The adaptive scale texture exhibits strong adaptability and achieves significant hydrodynamic effects. Therefore, the developed approach provides valuable insights for the optimization design of journal bearing systems.

Design and Evaluation of 5-DOF Magnetic Bearing System for Saucer-shaped Flywheel Battery

Design and Evaluation of 5-DOF Magnetic Bearing System for Saucer-shaped Flywheel Battery

Vibration Analysis of Rotating Elements of A Motor

Abstract: With the industrial revolution, the range of applications for rotating machinery in daily life as well as for industrial use in manufacturing and processing, nuclear power plants, automobiles, oil & gas refineries, etc., has greatly expanded. And for all this rotating machinery, the problems brought on by bearing faults significantly contribute to machine failure. Machine Design courses usually teach students how to design a system consisting of a shaft and its bearings under rotating, bending, transverse, axial, and torsional loads. Most textbooks cover Rayleigh's and Holzer's methods, which do not cover other important dynamic effects in shaft and bearing system design. The diameter of the shaft is calculated and then the deflection of the shaft is evaluated by using static deflection formulas. However, this assumption can cause serious errors in shafts' deflection due to eccentric and nonaligned gears mounted on the shaft. The authors addressed this potential manufacturing defect issue in a Machine Design class as a term project, which required students to transfer and apply content knowledge from their dynamics and vibrations’ courses. This paper presents all aspects of this successful experience of implementing ABET strategies in the engineering classroom to maximize its reach and potential impact.

Design and Control of Multicoil Active Magnetic Bearing System for High-Speed Application

In the rotating machinery sector, active magnetic bearing (AMB) has drawn great attention due to its benefits over the conventional bearing system. The high-speed technology is enhanced by AMBs, which also reduce maintenance costs and eliminate friction loss. This paper presents a unique, simpler, efficient design and hardware implementation for high-speed applications using two-coil I-type active magnetic bearings. To maintain the 10 mm air gap between the actuator and the rotor, two categories of controllers have been designed for the proposed system to control the position and another for detecting the coil current through the power amplifier. The AMB system is incorporated into a 3D finite element model for determining magnetic properties. The magnetic analysis is then carried out under various situations, and the attractive force characteristics have been evaluated for this suggested system to check the performance of the multicoil AMB system along with the stability analysis. The system is designed and simulated in MATLAB Simulink and implemented in hardware to validate the different outputs viz. position response and current response. Finally, an AC magnet is designed to rotate the rotor after the levitation, and a higher speed of 19,643 rpm is achieved in comparison to conventional bearings, which can be utilized in different industrial applications.

A fuzzy logic neural network algorithm for compressor crankshaft-rolling bearing system optimization

Taking the crankshaft-rolling bearing system in a certain type of compressor as the research objective, dynamic analysis software is used to conduct detailed dynamic analysis and optimal design under the rated power of the compressor. Using Hertz mathematical formula and the analysis method of the superstatic orientation problem, the relationship expression between the bearing force and deformation of the rolling bearing is solved, and the dynamic analysis model of the elastic crankshaft-rolling bearing system is constructed in the simulation software ADAMS. The weighted average amplitude of the center of the neck between the main bearings is used as the target, and the center line of the compressor cylinder is selected as the design variable. Finally, an example analysis shows that by introducing the fuzzy logic neural network algorithm into the compressor crankshaft-rolling bearing system design, the optimal solution between the design variables and the objective function can be obtained, which is of great significance to the subsequent compressor dynamic design.

Investigation of the orbit-spinning behaviors of the outer ring in a full ceramic ball bearing-steel pedestal system in wide temperature ranges

Owing to the difference in thermal deformation of the ceramic outer ring and steel pedestal, the outer ring experiences orbital and spinning motions in the fit clearance in wide temperature ranges, which has significant impacts on the bearing performance. In this paper, a dynamic model considering the temperature-related clearance is proposed, and the interactions between bearing and pedestal are calculated with a loose outer ring boundary condition. The orbit and spinning speeds are obtained, and the parameters concerning the speed ratio are used to evaluate the dynamic behaviors of the outer ring. Parametric analyses of temperature, rotation speed, and external load are conducted, and the results are verified through an experiment. The results show that changes in orbit-spinning behaviors are produced by variations in contact forces and area, and increased axial preload improves the stability of the bearing system. The results provide insights on bearing dynamics, and are useful for the design of ceramic bearing systems.

An efficient approach for LCC-based optimum design of lead-rubber base isolation system via FFD and analysis of variance (ANOVA)

A framework for optimal design of lead rubber bearing (LRB) system is introduced based on the initial and life cycle cost of structures. The purpose of this framework is to minimize the initial and life cycle cost of building and simultaneously improve the seismic performance of the base isolated structure. Endurance time (ET) method is used to predict the seismic response of the building at continuous levels of hazard intensity. Before implementing the optimization process, a full factorial design is utilized, and the seismic performance of a total of 128 lead rubber base isolated structures with varying LRB design parameters is assessed using the ET analysis method. Accordingly, the parameters with the most significant impact on the responses are determined by the analysis of variance. These parameters are used as design variables in a multi-objective genetic algorithm to minimize the initial and life cycle cost of the building with LRB system. The cost analysis of the system requires evaluation of initial costs including the costs associated with the implementation of LRBs. To date, no appropriate cost model has been proposed for LRB systems in the literature; therefore, a simplified cost model for LRBs is developed. Also, a life cycle cost model is used to evaluate the structural performance in the form of economic measures based on the results obtained from the ET analysis. In order to illustrate the method, a prototype six-story building is studied here. According to the results, the proposed approach is found to be effective in reducing the initial and life cycle cost of the building with an acceptable amount of computational effort.

A comprehensive study on the speed-varying stiffness of ball bearing under different load conditions

The stiffness as one of the most important dynamic characteristics of ball bearing, has a great influence on the service performance of bearing and rotor systems. To obtain and analyze the stiffness matrix of ball bearing under arbitrary load conditions, this paper proposed a novel mathematical method for ball bearing modeling and stiffness matrix calculation based on a new initial condition assumption. Based on this, a comprehensive and systematical study to investigate the effect of rotating speed on the stiffness for ball bearing under three typical load conditions has been presented (the pure axial load condition, the pure radial load condition and the combined loads condition). And the influences of bearing basis structure parameters including the internal clearance, ball diameter, inner and outer raceway curvature coefficients on the change rule of the stiffness along with speed of ball bearing under three typical load conditions have been given. The results show that the proposed model has a high versatility, and the change rules of the stiffness along with rotating speed are greatly influenced by the load conditions, bearing structural parameters. Therefore, this paper not only presents a complete algorithm for the modeling and stiffness calculation of ball bearing under arbitrary load conditions, but also provides important guidance for the design of bearing and rotor systems.

Design and optimisation of advanced bearing system for ultra-precision plastic electronics production systems

PurposeThe paper aims to use aluminium alloy to substitute steel as the main material of ultra-precision hydro-static bearing system for an ultra-precision plastic electronics production system to lower the manufacturing cost. The total cost of diamond turning and nickel-based electroless coating of an aluminium alloy bearing is expected to be less than the cost of manufacturing a stainless steel bearing.Design/methodology/approachThe paper used a large amount of theoretical calculation to obtain optimal specifications of the bearing system. ANSYS modelling was selected to simulate the deflection of the bearing shaft under high oil pressure. Hundreds of measurements were conducted after the bearing had been manufactured.FindingsThe paper provides industrial application insights on using aluminium alloy with a high-quality nickle-based electroless coating as a successful substitution of stainless steel. This created a more economic hydro-static bearing system.Research limitations/implicationsBecause of the time limit, different rotational speed tests shall be conducted in the future.Practical implicationsThe paper provides implications for the application of nickel-based electroless coating to improve the surface property and bending strength of aluminium alloy, as well as classifying ultra-precision diamond turning as an economic finishing process.Originality/valueThis paper has identified the importance of aluminium alloy with a nickel-based electroless coating as the substitution of stainless steel in a precision hydro-static bearing system.

A fractional order PID control strategy in active magnetic bearing systems

Active Magnetic Bearings (AMBs) are broadly utilized for high angular speed machines such as turbo-machinery, compressors and high speed motors. In AMBs, the rotating parts run without physical contacts with the moving parts. This reduces maintenance costs and minimizes friction. Generally, the applied loads cause extra gyroscopic effects on the rotating parts especially under high-speed operation. Although conventional PID controllers are widely employed in these systems, they experience some stability problems under high dynamic operations. In this paper, the design of an active magnetic bearing system based on fractional order PID (FOPID) controllers to enhance system dynamics and stability is introduced. The suggested controller gains are optimized utilizing particle swarm optimization (PSO) approach. An ordinary AMB system framework with four radial bearings is used to assess the suggested FOPID controller against routine PID controllers. The system current limitation, overshoot constraint, and time specifications requirements are deemed in the optimization technique.

Hydrodynamic journal bearing lubricated with a ferrofluid

PurposeThis paper aims to investigate the performance of a ferrofluid-based hydrodynamic journal bearing system.Design/methodology/approachThis paper presents a new design of ferrofluid-based hydrodynamic journal bearing. An experimental set-up consisting of a magnetic shaft along with a brass bearing was modified and developed. A permanent magnet was used to make the selected shaft material magnetic. The load and speed were varied to conduct the analyses for different test conditions.FindingsThe paper provides information about a design of ferrofluid-based journal bearing and its improved performances. For moderate to higher loads at different shaft speeds, it was found that because of the magnetization effect, the maximum film pressure in case of a ferrofluid lubricant increased up to approximately 60 per cent, compared with that of the conventional lubricant-based journal bearing system. Besides, the temperature rise was found smaller for ferrofluid lubricants, thus making the system cooler while running.Originality/valueThis paper offers a new design of magnetic bearing system for the experimental analysis by utilizing a magnetic shaft with a non-magnetic bearing. The present ferrofluid-based bearing design is less complicated from manufacturing point of view.

Chaotic Behaviour Investigation of a Front Opposed-Hemispherical Spiral-Grooved Air Bearing System

In recent years, spiral-grooved air bearing systems have attracted much attention and are especially useful in precision instruments and machines with spindles that rotate at high speed. Load support can be multidirectional and this type of bearing can also be very rigid. Studies show that some of the design problems encountered are dynamic and include critical speed, nonlinearity, gas film pressure, unbalanced rotors, and even poor design, all of which can result in the generation of chaotic aperiodic motion and instability under certain conditions. Such irregular motion on a large scale can cause severe damage to a machine or instrument. Therefore, understanding the conditions under which aperiodic behaviour and vibration arise is crucial for prevention. In this study, numerical analysis, including the Finite Difference and Differential Transformation Methods, is used to study these effects in detail in a front opposed-hemispherical spiral-grooved air bearing system. It was found that different rotor masses and bearing number could cause undesirable behaviour including periodic, subperiodic, quasi-periodic, and chaotic motion. The results obtained in this study can be used as a basis for future bearing system design and the prevention of instability.

Tests with a hybrid bearing for a flywheel energy storage system

This paper describes the design and experimental test of a passive magnetic bearing system composed by a superconductor magnetic bearing (SMB) and a permanent magnet bearing (PMB). This bearing setup is part of a flywheel energy storage system. The advantage of using a passive bearing system is that it offers low friction without the need of a magnetic bearing controller, increasing the reliability and decreasing the energy consumption. The first set of tests were quasi-static radial and axial force measurements of the PMB operating alone and together with the SMB. As the PMB is intrinsically unstable in one degree of freedom, the operation of the SMB together with the PMB is necessary to stabilize the system. After that, dynamic measurements were made for the SMB operating alone and together with the PMB. The resonant speeds were identified and the bearing radial and axial forces were also measured for the SMB and SMB + PMB operation. These results indicate that the studied bearing set is technologically feasible to be used in flywheel energy storage systems.

Research of Dynamics of the Rotor with Three-film Bearings

Rotating floating rings in the rotor bearings are widely used for decrease of rotor vibrations in small rotor machines. Such bearings are named two-film, because have two lubricant films.Dynamics of the rotor with floating ring bearings is investigated in details in [1–3]. The charging system also use non-rotating floating rings in turbochargers of internal combustion engines [4].In some combinations of design and condition parameters of the rotor bearing system, the dimension of rotor and rings motion trajectory can essentially increase, though it is still limited [1–3]. To decrease journal and ring oscillation amplitudes and loadings affecting the bearing, the design with three lubricant films can be used. It is achieved through installation of the floating ring package into a rotor machine case. Floating ring bearing package consists of one non-rotating floating ring (NF ring) and two rotating floating rings (RF ring).

Optimum design of lead-rubber bearing system with uncertainty parameters

In this study, a non-stationary random earthquake Clough-Penzien model is used to describe earthquake ground motion. Using stochastic direct integration in combination with an equivalent linear method, a solution is established to describe the non-stationary response of lead-rubber bearing (LRB) system to a stochastic earthquake. Two parameters are used to develop an optimization method for bearing design: the post-yielding stiffness and the normalized yield strength of the isolation bearing. Using the minimization of the maximum energy response level of the upper structure subjected to an earthquake as an objective function, and with the constraints that the bearing failure probability is no more than 5% and the second shape factor of the bearing is less than 5, a calculation method for the two optimal design parameters is presented. In this optimization process, the radial basis function (RBF) response surface was applied, instead of the implicit objective function and constraints, and a sequential quadratic programming (SQP) algorithm was used to solve the optimization problems. By considering the uncertainties of the structural parameters and seismic ground motion input parameters for the optimization of the bearing design, convex set models (such as the interval model and ellipsoidal model) are used to describe the uncertainty parameters. Subsequently, the optimal bearing design parameters were expanded at their median values into first-order Taylor series expansions, and then, the Lagrange multipliers method was used to determine the upper and lower boundaries of the parameters. Moreover, using a calculation example, the impacts of site soil parameters, such as input peak ground acceleration, bearing diameter and rubber shore hardness on the optimization parameters, are investigated.

Unsteady Thrust Force Loading of a Turbocharger Rotor During Engine Operation

The bearing system of a turbocharger has to keep the rotor in the specified position and thus has to withstand the rotor forces that result from turbocharger operation. Hence, its components need to be designed in consideration of the bearing loads that have to be expected. The applied bearing system design also has significant influence on the overall efficiency of the turbocharger and impacts the performance of the combustion engine. It has to ideally fulfill the trade-off between bearing friction and load capacity. For example, the achievable engine’s low end-torque is reduced, if the bearing system produces more friction losses than inherently unavoidable for safe and durable operation because a higher portion of available turbine power needs to be employed to compensate bearing losses instead of providing boost pressure. Moreover, also transient turbocharger rotor speed up can be compromised and hence the response of the turbocharged combustion engine to a load step becomes less performant than it could be. Besides the radial bearings, the thrust bearing is a component that needs certain attention. It can already contribute to approximately 30% of the overall bearing friction, even if no load is applied and this portion further increases under thrust load. It has to withstand the net thrust load of the rotor under all operating conditions resulting from the superimposed aerodynamic forces that the compressor and the turbine wheel produce. A challenge for the determination of the thrust forces appearing on engine is the nonsteady loading under pulsating conditions. The thrust force will alternate with the pulse frequency over an engine cycle, which is caused by both the engine exhaust gas pressure pulses on the turbine stage and—to a smaller amount—the nonsteady compressor operation due to the reciprocating operation of the cylinders. The conducted experimental investigations on the axial rotor motion as well as the thrust force alternations under on-engine conditions employ a specially prepared compressor lock nut in combination with an eddy-current sensor. The second derivative of this signal can be used to estimate the occurring thrust force changes. Moreover, a modified thrust bearing—equipped with strain gauges—was used to cross check the results from position measurement and thrust force modeling. All experimental results are compared with an analytical thrust force model that relies on the simultaneously measured, crank angle resolved pressure signals before and after the compressor and turbine stage. The results give insight into the axial turbocharger rotor oscillations occurring during an engine cycle for several engine operating points. Furthermore, they allow a judgment of the accuracy of thrust force modeling approaches that are based on measured pressures.

Optimum Design of Lead-Rubber Bearing System Under the Non-Stationary Random Earthquake Ground Motion

Optimum Design of Lead-Rubber Bearing System Under the Non-Stationary Random Earthquake Ground Motion

Modeling and Analysis of Coupling Performance Between Passive Magnetic Bearing and Hybrid Magnetic Radial Bearing for Magnetically Suspended Flywheel

In this paper, the design and development of a novel magnetic bearing (MB) system which consists of a passive magnetic bearing (PMB) with two pairs of passive permanent magnet rings and hybrid magnetic radial bearing (HMRB) used in magnetic bearing flywheel (MBFW) of control moment gyroscope (CMG) for agile satellite application are presented. The models of PMB and HMRB are proposed and their performances of force-current, force-position, and torque-angle are analyzed using the equivalent magnetic circuit method, finite element method (FEM), and equivalent magnetic charge method. The coupling forces between x and y position degrees of freedom (DOFs) of the HMRB, between the coil current in x-axis and y-axis, between the radial and the axial position DOF of the HMRB, and the coupling force and torque between the translating motion along the x (or y) axis and the rotary motion around x (or y) axis. These coupling problems of the novel MB system are proposed and clarified in this paper. An example is given to clarify the mathematical models and the coupling problems, and the linearized model is proposed for controller design of the MB system.

The effects of dimensional manufacturing tolerances on stability of a symmetric hydrodynamic journal bearing rotor system – an experimental investigation

The importance of gross dimensions on the design and operation of hydrodynamic journal bearing system are widely understood, however, the effects of manufacturing tolerances have only been macroscopically analysed. Building on previous theoretical analyses, an experimental investigation on the effect of dimensional manufacturing tolerances is presented. Importantly, the study looks at individual effects and combined effects. The experimental data suggested that the error created by manufacturing tolerances in estimating the onset of oil film instability can be as much as ±20 per cent, depending on the steady state operating position. This finding shows that in order to minimize the effect of manufacturing tolerances on system stability, the hydrodynamic journal bearing system should be designed to operate at a modified Sommerfeld number greater than 0.1, where the effects of manufacturing tolerances on system stability are negligible.