• Journal of the Korean Society of Manufacturing Process Engineers
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• v.1 no.1
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• pp.101-108
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• 2002

In the grinding process, the degree of the sharpness in wheel gram affects the surface roughness and the dimensional accuracy. If a wheel with dull grains is used, the grinding force will be increased and the surface roughness deteriorated. To produce a precision component, the magnitude of parameters related to the wear amount of a grinding wheel has to be limited. In this study, a variation of the grinding force and the surface roughness were measured to seek the machining characteristics of the W A and CBN wheels. From the wear amount of the grinding wheel and the removal rate of workpiece, the grinding ratio was calculated. And also the wheel life was determined at a rapid decreasing point of the grinding ratio. The difference between the surface of wheel-workpiece before grinding and after wheel life was clearly verified with a microscopic photo.

• Tribology and Lubricants
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• v.39 no.3
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• pp.94-101
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• 2023

Automotive wheel bearings are a critical component of vehicles that support their weight and facilitate rotation. Life and stiffness are significant performance characteristics of wheel bearings. Designing wheel bearings involves finding optimal design variables that satisfy both performances. CO₂ emission reduction and fuel efficiency regulations attribute to the recent increase in design requirements for lightweight and compact automotive parts while maintaining performance. However, achieving a design that maintains performance while reducing weight poses challenges, as performance and weight are generally inversely proportional. In this study, we perform design optimization of automotive wheel bearings considering life and stiffness. We develop a program that calculates the basic rated life and modified rated life based on international standards for evaluating the life of wheel bearings. We develop a regression equation using regression analysis to address the time-consuming stiffness analysis during repetitive analysis. We perform ANOVA and main effect analyses to understand the statistical characteristics of the developed regression equation. Furthermore, we verify its reliability by comparing the predicted and test results. We perform design optimization using the developed life prediction program, stiffness regression equation and weight regression equation. We select bearing specifications and geometry as design variables, weight as the cost function, and life and stiffness as constraints. Through design optimization, we investigate the influence of design variables on the cost function and constraints by comparing the initial and optimal design values.

• International Journal of Railway
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• v.1 no.3
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• pp.83-88
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• 2008

Since the 1990's the fleet of the Dutch Railways showed a dramatic decrease in wheel tyre life. This lifetime reduction led to an unacceptable increase in life cycle costs. Therefore Lloyd's Register Rail has proposed to NedTrain to investigate the possibilities of improving the wheel tyre life. Three improvements were determined as most promising and relatively easy to achieve: - Profile optimisation for Rolling Contact Fatigue (RCF) reduction - a new wheel profile has been developed with a better resistance against rolling contact fatigue of the wheel tread. The profile has been implemented on single deck intercity trains and shows an increase in wheel tyre life of 30%. - Selection of improved wheel tyre materials - combining information from literature and experiences of manufacturers five alternative wheel tyre materials have been selected and are now being tested in practice. - Optimisation of the maintenance strategy - an alternative, preventative maintenance regime has been developed. With this Scraping regime, during short term maintenance every wheel is reprofiled. Higher mileages are reached and savings on life cycle costs up to 50% and more have been achieved. Unplanned maintenance goes down with $30{\sim}60%$. The results from field tests, using a reference group for comparison, and preliminary results after implementation show that the increase in wheel tyre life that is achieved with this project is significant. The results will continue to be monitored using the asset management tool 'Wheel Watch', that was specially developed for this project and is also described in this paper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.341-349
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• 2005

Damage often occurs on the surface of railway wheel by wheel-rail contact fatigue. It should be removed before reaching wheel failure, because wheel failure can cause derailment with loss of life and property. The increase or decrease of the contact fatigue life by the metal removal of the contact surface were shown by many researchers, but it has not explained precisely why fatigue life increases or decreases. In this study, the effect of metal removal depth on the contact fatigue life for railway wheel has been evaluated by applying finite element analysis. It has been revealed that the residual stress and the plastic flow are the main factors determining the fatigue life. The railway wheel has the initial residual stress formed during the manufacturing process, and the residual stress is changed by thermal stress induced by braking. It has been found that the initial residual stress determines the amount of metal removal depth. Also, the effects of the initial residual stress and metal removal on the contact fatigue lift has been estimated, and an equation is proposed to decide the optimal metal removal depth for maximizing the contact fatigue life.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.692-697
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• 2004

Damage often occurs on the surface of railway wheel by wheel-rail contact fatigue. It should be removed before reaching wheel failure, because wheel failure can cause derailment with loss of life and property. The increase or decrease of the contact fatigue life by the metal removal of the contact surface were shown by many researchers, but it has not explained precisely why fatigue life increases or decreases. In this study, the effect of metal removal depth on the contact fatigue life for railway wheel has been evaluated by applying finite element analysis. It has been revealed that the residual stress and the plastic flow are the main factors determining the fatigue life. Finally, the contact fatigue life according to metal removal has been estimated.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.3
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• pp.59-65
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• 2002

In the grinding process, the degree of the sharpness in wheel grain affects the surface roughness and the dimensional accuracy. If a wheel with dull grains is used, te grinding force will be increased and the surface roughness deteriorated. To produce a precision component, the magnitude of parameters related to the wear amount of a grinding wheel has to be limited. In this study, a variation of the grinding force and the surface roughness were measured to seek the machining characteristics of the WA and CBN wheels. From the wear amount of the grinding wheel and the removal rate of workpiece, the grinding ratio was calculated. And also the wheel life was determined at a rapid decreasing point of the grinding ratio. The difference between the surface of wheel-workpiece before grinding and after wheel life was clearly verified with a microscopic photo.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.670-673
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• 2002

Automotive wheel bearings are one of the most important components to guarantee the service life of a passenger car. The endurance life of a bearing is affected by many parameters such as material properties, heat treatment, lubrication conditions, temperature, loading conditions, bearing geometry, internal clearance and so on. In this paper, we analyze the relation between loads and deformations of wheel bearing units. On the basis of it we calculate the endurance life of wheel bearing units and analyze the contribution of bearing geometric parameters on the endurance life by using Taguchi method.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.137-143
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• 2008

For most bearings, it is a common requirement to have long durability. Especially wheel bearing fatigue life is the most important in automotive quality. The contact fatigue life analysis of automotive wheel bearing considering real raceway rough surface is presented in this paper. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions; the subsurface stress field is obtained using rectangular patch solutions. Mesoscopic multiaxial fatigue criterion which can yield satisfactory results for non-proportional loading is then applied to predict fatigue damage. Suitable counting method and damage rule were used to calculate the fatigue life of random loading caused by rough surface. The life analysis considering real rough surface of wheel bearing raceway is in good agreement with the experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.6
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• pp.498-505
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• 2010

In-Wheel System is a high-efficiency system to supply a new concept of platform which raises the efficiency of motor drive system and applies it to an environment-friendly automobile by installing a highly efficient electric motor directly to wheels and removing factors of power train. The proliferation of these systems is directly related to the safety of our lives, so check the reliability of the part in the development phase and should be certified. Reliability is the ability of a system or component to perform its required functions under stated conditions for a specified period of time. This paper presents to the verification methods for durability, one of reliability assessments of the Motor, the study calculated acceleration and deceleration torque and the effective torque from driving conditions of In-Wheel Motor, and based on this, it reduced the test time and suggested the verification methods of In-Wheel Motor reliability through the accelerated life test.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1072-1077
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• 2002

A degree of sharpness in wheel grains affects the surface roughness and dimensional accuracy in the grinding process. If a wheel with dull grains is used, the grinding force is increased and the surface roughness is deteriorated. In ovder to produce a precision component economically, the magnitude of the wear amount in the grinding wheel has to be limited. In this study, experimental evaluation of a wheel life varying with the grinding ratio and static grinding force was conducted. The grinding ratio and grinding force were measured to seek the grinding performance of the WA wheel. The relationship between the grinding ratio and static grinding force was presented.