• Tribology and Lubricants
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• v.10 no.1
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• pp.62-68
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• 1994

The analysis of statically indeterminate bearing-shaft system was investigated. The moment loads and misalignment angles which were induced in the ball bearings were determined, and the influence of span length of this system on the moment loads and fatigue lives was identified. The sliding and spinning speeds between balls and raceways which affected the performance of ball bearing evaluated. The equation to estimate the cage speed of ball bearing under moment loads was proposed. This equation had been verified by the test results of measuring of cage speed, which was useful to the prediction of ball bearing under moment loads.

• Journal of the Korean Geosynthetics Society
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• v.5 no.1
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• pp.9-14
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• 2006

The reinforced soil retaining wall structures of serious types with environmental are widely expanding more and more in Korea, which divided conventional type's reinforced soil retaining wall on segmental retaining wall. The causes of most crack occurred at block in reinforced soil retaining wall structure caused by the differential settlement of foundation. It is difference of settlement for significant factor that with overall slope stability. In this study, design assessment of foundation bearing capacity related to differential settlement of foundation ground was considered. And, also, through case study, the countermeasure methods and its application were suggested that the bearing capacity of foundation had to stabilize. The foundation ground in charge of bearing capacity should be affected by the resisting force of sliding, because the foundation parts of reinforced soil retaining wall were belongs to potential slope sliding area in overall stabilizing including retaining wall structures. Therefore, the analyzing or the designing of bearing capacity for foundation should be considered control capacity on the overall slope sliding.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2597-2605
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• 1994

The wear behavior of two types of $Si_3N_4$ exposed to high and low humidity was examined at various sliding speeds, using bearing steel as disk material under pin-on-disk type sliding conditions. Higher wear rates were obtained at a high humidity than at a low humidity. As the sliding speed was increased, the wear rates were decreased and the effect of humidity on the wear rates of $Si_3N_4$ was reduced. The result that the $Si_3N_4$ pin showed higher wear rate under the high humidity condition was explained by the decrease in microhardness of $Si_3N_4$ due to the chemisorbed moisture on the pin and plowing action by the hard particles of $Fe_2O_3$ from the disk. An increase in the sliding speed is supposed to reduce the effect of humidity on the wear rate of $Si_3N_4$ by raising the average temperature of the disk surface and the local temperature at pin-disk contact point.

• Earthquakes and Structures
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• v.16 no.6
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• pp.641-654
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• 2019

This paper investigates the seismic response of a typical non-navigable continuous girder bridge isolated with friction sliding bearings of the Hong Kong-Zhuhai-Macao link projects in China. The effectiveness of the friction pendulum system (FPS) and accuracy of the numerical model were evaluated by a 1/20 scaled bridge model using shaking table tests. Based on the hysteretic properties of friction pendulum system (FPS), double concave friction pendulum (DCFP), and triple friction pendulum system (TFPS), seismic response analyses of isolated bridges with the three sliding-type bearings are systematically carried out considering soil-pile interaction under offshore soft clay conditions. The fast nonlinear analysis (FNA) method and response spectrum are employed to investigate the seismic response of isolated offshore bridge structures. The numerical results show that the implementation of the three sliding-type bearings effectively reduce the base shear and bending moment of the reinforced concrete pier, at the cost of increasing the absolute displacement of the bridge superstructure. Furthermore, the TFPS and DCFP bearings show better isolation effect than FPS bearing for the example continuous girder bridge.

• Smart Structures and Systems
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• v.17 no.5
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• pp.709-724
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• 2016

This study investigates the optimum design parameters of a superelastic friction base isolator (S-FBI) system through a multi-objective genetic algorithm to improve the performance of isolated buildings against near-fault earthquakes. The S-FBI system consists of a flat steel-PTFE sliding bearing and superelastic NiTi shape memory alloy (SMA) cables. Sliding bearing limits the transfer of shear across the isolation interface and provides damping from sliding friction. SMA cables provide restoring force capability to the isolation system together with additional damping characteristics. A three-story building is modeled with S-FBI isolation system. Multiple-objective numerical optimization that simultaneously minimizes isolation-level displacements and superstructure response is carried out with a genetic algorithm in order to optimize S-FBI system. Nonlinear time history analyses of the building with optimal S-FBI system are performed. A set of 20 near-fault ground motion records are used in numerical simulations. Results show that S-FBI system successfully control response of the buildings against near-fault earthquakes without sacrificing in isolation efficacy and producing large isolation-level deformations.

• Journal of Drive and Control
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• v.9 no.4
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• pp.26-31
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• 2012

Friction reduction between sliding hydraulic machine components is required to improve efficiency and reliability of hydraulic machineries. It is recently reported that surface texturing on sliding bearing surfaces can reduce the friction force highly. In this paper, numerical analysis is carried out to investigate the effect of dimple numbers and inlet boundary pressures on the lubrication characteristics of a parallel sliding bearing using a commercial computational fluid dynamics (CFD) code, FLUENT. The results show that the pressure distribution, load capacity, dimensionless friction force and leakage with dimple number and their locations, and inlet pressures. The overall lubrication characteristics are highly affected by dimple numbers and boundary pressure. The numerical method adopted and results can be used in design of efficient hydraulic machine components.

• Tribology and Lubricants
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• v.13 no.2
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• pp.52-59
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• 1997

An experimental study is presented for the characteristics of the high temperature superconductor as an application of the repulsive type magnetic bearing. A ring shaped YBCO type superconductor and Neodium permanent magnets are employed for the experiment. For the case of field cooling, superconductor shows strong repulsive force, which is due to the Meissner effect, as the gap between the superconductor and the magnet gets closer. The repulsive force variation with respect to the gap change shows hysterisis characteristics. The area of the loop of the hysterisis curve represents the dissipation of energy, which reveals that the magnetic bearing with superconductor has large damping. The effect of the initial gap and the magnetic flux density on the repulsive force is analyzed experimentally and the static stiffness variation is calculated from the measured repulsive force variation. The relative sliding velocity between the superconductor and the magnet has little effect on the repulsive force which is quite different from the usual sliding element bearing. As the initial gap for the field cooling becomes larger, the maximum repulsive force at the minimum gap increases and approaches to the value for the case of zero field cooling.

• Geomechanics and Engineering
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• v.31 no.6
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• pp.599-614
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• 2022

One of the methods of stabilizing retaining walls, embankments, and deep excavations is the implementation of plate anchors (like the Geolock wall anchor systems). Back-to-back Mechanically Stabilized Earth (BBMSE) walls are common stabilized earth structures that can be used for bridge ramps. But so far, the analysis of the interactive behavior of two back-to-back anchored walls (BBAW) by double-plates anchors (constructed closely from each other and subjected to the limited-breadth vertical loading) including interference of their failure and sliding surfaces has not been the subject of comprehensive studies. Indeed, in this compound system, the interaction of sliding wedges of these two back-to-back walls considering the shear failure wedge of the foundation, significantly impresses on the foundation bearing capacity, adjacent walls displacements and deformations, and their stability. In this study, the effect of horizontal distance between two walls (W), breadth of loading plate (B), and position of vertical loading was investigated experimentally. In addition, the comparison of using single and equivalent double-plate anchors was evaluated. The loading plate bearing capacity and displacements, and deformations of BBAW were measured and the results are presented. To evaluate the shape, form, and how the critical failure surfaces of the soil behind the walls and beneath the foundation intersect with one another, the Particle Image Velocimetry (PIV) technique was applied. The experimental tests results showed that in this composite system (two adjacent-loaded BBAW) the effective distance of walls is about W = 2.5*H (H: height of walls) and the foundation effective breadth is about B = H, concerning foundation bearing capacity, walls horizontal displacements and their deformations. For more amounts of W and B, the foundation and walls can be designed and analyzed individually. Besides, in this compound system, the foundation bearing capacity is an exponential function of the System Geometry Variable (SGV) whereas walls displacements are a quadratic function of it. Finally, as an important achievement, doubling the plates of anchors can facilitate using concrete walls, which have limitations in tolerating curvature.

• Tribology and Lubricants
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• v.11 no.1
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• pp.27-36
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• 1995

Maximum allowable PV values of oilless composite bearing materials (70% epoxy-resin/30% Graphite) were measured and compared at various types of test rigs that have different contact geometry and the operating conditions. Test results showed that material failure was mainly characterized by the sharp increase in both coefficient of friction and surface temperature, and different PV values were measured under different Contact geometry. The discrepancy in measurement of PV values was analyzed in the light of theoretical frictional heating analysis. Results show that surface temperature rise depends on its contact geometry, and PV values could be overestimated in the testing conditions of high sliding velocity. Test data of different contact geometry were normalized by using a normalized contact pressure and sliding velocity; it showed a good correlation. This work suggests that normalized PV values could be more effective in evaluating bearing materials than conventional PV values for a design parameter of journal bearings.

• The KSFM Journal of Fluid Machinery
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• v.9 no.5 s.38
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• pp.7-13
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• 2006

In the present study, we develop an analysis module to be applicable to design of sliding thrust bearings. The pressure equation is solved by using the finite element method. Average lubricant temperature is obtained from using the energy balance method. The module developed has been applied to three types of thrust bearing, such as tapered-land thrust bearings of angular and diamond types, and tilting-pad thrust bearings. Effects of the dam of the tapered-lad thrust bearings have also been investigated. It has been seen that the tapered-land thrust bearings of angular type result in the highest load capacity, while the tilting pad thrust bearings result in the lowest lubricant temperature. It has also been seen that the dam in the tapered-land thrust bearings increases both the load capacity and lubricant temperature.