• Tribology and Lubricants
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• v.11 no.5
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• pp.162-171
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• 1995

The application of reciprocating engine crankshaft bearings is of particular importance and interest among the plain bearing, not only because the sheer volume of intemal combustion engines now produced, but because the severe operating conditions they are subjected to. Demands for better performances of crankshaft bearings have provide an important impetus in the development of bearings and bearing materials. As engine design progresses toward higher outpt and higher efficiency, crankshaft bearings must perform under more seveve operating conditions. Higher load, temperature, and speed as well as lower viscosity oil are applied to the bearing sysem, resulting in a smaller minimum oil film thickness. This means more solid-solid contact between the shaft and bearing, and the bearing is exposed to more danger of seizure. Some engines may experience bearing seizure problems. However, understanding about the seizure behavior and mechanism is far from being enough. Seizure resistance of a bearing-shaft system will be affected by the properties of the shaft and bearing, especially their materials and surface texture. Commonly used engine bearing materials include Al-Pb-Si, Al-Sn-Si, Al-Sn, and Cu-Pb with Pb-Sn-Cu overlay. These materials have very different properties. They showed different behaviors dering seizure tests and seizure may occur with different mechanism for different bearing material. Shaft materials also affect the seizure resistance of the system. Surface texture of the bearing and shaft have apparent effects on the lubrication and solid-solid contact pattern, and therefore will affect the seizure behavior of the system. Bearings and shafts which are made of different materials and have different surface textures have been tested and analyzed. Their effects on seizure resistance are discussed and possible seizure mechanisms for different beatings are presented in this paper.

• Structural Engineering and Mechanics
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• v.38 no.3
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• pp.361-384
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• 2011

Earlier studies on hollow-circular rubber bearings, all of which are conducted for steel-reinforced bearings, indicate that the hole presence not only decreases the compression modulus of the bearing but also increases the maximum shear strain developing in the bearing due to compression, both of which are basic design parameters also for fiber-reinforced rubber bearings. This paper presents analytical solutions to the compression problem of hollow-circular fiber-reinforced rubber bearings. The problem is handled using the most-recent formulation of the "pressure method". The analytical solutions are, then, used to investigate the effects of reinforcement flexibility and hole presence on bearing's compression modulus and maximum shear strain in the bearing in view of four key parameters: (i) reinforcement extensibility, (ii) hole size, (iii) bearing's shape factor and (iv) rubber compressibility. It is shown that the compression stiffness of a hollow-circular fiber-reinforced bearing may decrease considerably as reinforcement flexibility and/or hole size increases particularly if the shape factor of the bearing is high and rubber compressibility is not negligible. Numerical studies also show that the existence of even a very small hole can increase the maximum shear strain in the bearing significantly, which has to be considered in the design of such annular bearings.

• 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.

• Tribology and Lubricants
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• v.33 no.4
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• pp.168-186
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• 2017

This paper presents a wear analysis procedure for calculating the wear of journal bearings during the start-up and coast-down cycles of a motoring stripped-down single cylinder engine operating with a tilted shaft. In order to decide whether the lubrication state of a journal bearing is in the mixed-elasto-hydrodynamic lubrication regime, we utilize lift-off speed and MOFT (most oil film thickness) under mixed-elasto-hydrodynamic lubrication regime at the corresponding aligned shaft. We formulate an equation for the modified film thickness in a misaligned journal bearing considering the additional wear volume described in Part I of this study. For this, we use the calculation results of the degree of misalignment and tilting angle obtained after finding the eccentricities of the two bearings supporting the crankshaft of a single cylinder engine. In this Part II, we calculate the wear of journal bearings using the fractional film defect coefficient, the asperity load sharing factor, and the modified specific wear rate for the application of mixed-elasto-hydrodynamic lubrication regime. We show that the accumulated wear volume after turning the ignition switch on and off once, increases to ${\sigma}=39{\mu}m$ and then decreases from ${\sigma}=39{\mu}m$ with increasing in surface roughness.

• Tribology and Lubricants
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• v.7 no.1
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• pp.28-34
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• 1991

The performance of the counterrotating floating ring journal bearing is analysed with isothermal finite bearing theory. The effect of counterrotating speed of the sleeve on the performance of the bearing is investigated. It is shown that counterrotating floating ring journal bearings properly designed can have considerable load capacity at the same counterrotating speed, while conventional circular journal bearing with one fluid film cannot. Investigating the relationship between the frictional torques on the ring due to the inner and outer films and the rotational speed of the ring, the stability of the equilibrium state is identified and the operating characteristics of the counterrotating floating ring journal bearing according to the method of acceleration or deceleration of the rotational speeds of the journal and sleeve are clarified. It is theoretically confirmed that floating ring journal bearings can be used in counterrotating journal-bearing system and become good substitutes for rolling bearings in counterrotating systems.

• Tribology and Lubricants
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• v.27 no.2
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• pp.71-76
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• 2011

In this study, the nondimensional load capacity of water hydrodynamic journal bearings is calculated. A generalized coordinate formulation is applied to handle the complexity of bearing geometry. A window-based analysis program is developed to analysis the cylindrical hydrostatic bearings. Load capacities are calculated according to some design parameters such as clearance, diameter of orifice, size of recesses and temperature. The results are presented and discussed.

• Tribology and Lubricants
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• v.18 no.5
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• pp.333-338
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• 2002

Results of theoretical investigations on acoustical properties of hydrodynamic journal bearings are presented. Nonlinear analysis including rotor imbalance is performed for a rotor-bearing system in order to obtain acoustical properties of hydrodynamic journal bearings. Furthermore, a cavitation algorithm, implementing the Jakobsson-Floberg-Olsson boundary condition, is adopted to predict cavitation regions in a fluid film. Acoustical properties of hydrodynamic journal bearings are identified through frequency analysis of oil pressure fluctuation calculated from the nonlinear transient analysis. The results show that the acoustical frequency spectra of the fluid film are pure tone spectra, containing the frequency of the shaft rotation and its super-harmonics. The analysis also shows that super-harmonics are predominant at the neighborhood of the fluid film reformation and rupture regions.

• Journal of Korean Society of Steel Construction
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• v.26 no.6
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• pp.559-570
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• 2014

In this study, compression and shear characteristics of laminated rubber bearings and lead rubber bearings with various parameters are investigated by using material and geometric nonlinear three-dimensional finite element analysis. Rubber coupon tests are performed to make a model of the laminated rubber bearings. In addition, the material constants of the rubber are calculated by the curve fitting process of stress-strain relationship. The finite element analysis and experimental tests of the laminate rubber bearings are used to verify the validity of the rubber material constants. It is seen that the compression behavior of the laminated rubber bearings and lead rubber bearings mainly varies depending on the first shape factors and their shear behavior significantly varies depending on the second shape factors. In addition, the horizontal stiffness and energy dissipation capacity of lead rubber bearing are increased when the diameter of a lead bar is increased.

• Journal of architectural history
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• v.28 no.3
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• pp.7-18
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• 2019

This study analyzed "Bukgwol Dohyeong (Drawing Plans for the Northern Section of Gyeongbokgung Palace)", which is an important source material for the restoration of the palace, by applying Paltaekron, the geomantic principle of bearings, in order to clarify the building layout principle of Gyeongbokgung Palace. Gyeongbokgung Palace shows the typical geographical conditions that meet the principle of Baesan Imsu (mountain in the back and water in the front) which takes Baegaksan Mountain as the main mountain and the overall layout of the buildings that meet the principle of 'Jeonchak Hugwan (narrow in the front and broad toward inside)' by using the natural topography that meets the principle of 'Jeonjeo Hugo (low in the front and higher toward back).' It is estimated that this layout and arrangement must have been led by geomantic principle of bearings. The analysis of the building layout plan of Gyeongbokgung Palace in the late Joseon Dynasty Period suggests the application of two methods: one is to divide central area from Gwanghwamun Gate to Geoncheongung Hall into eight layers and the other is to apply the bearings of the Eight Trigrams based on the building that becomes the center. As a result, the gate, main hall, and kitchen of all major buildings where the royal family lived are located in the auspicious bearings according to the geomantic principle of bearings while the spaces where people other than the royal family such as those who served the royal family and the officials operated in the palace or the hall that enshrines the ancestors such as Taewonjeong Hall are located in the ominous bearings. Therefore, the buildings of Gyeongbokgung Palace are arranged based on the geomantic principle of bearings.

• Tribology and Lubricants
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• v.2 no.2
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• pp.32-43
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• 1986

The mobility method is used for optimizing dynamically-loaded journal bearings. Connecting -rod bearings in both diesel and gasoline engines are optimized by parametric studies of bearing span and clearance. The inertia effect of the connecting-rod is also included in this study. Minimum film thickness, maximum film pressure, and friction loss are calculated to satisfy the design conditions in both engines.