• 풍력에너지저널
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• 제3권1호
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• pp.61-67
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• 2012

The loading test of wind turbine pitch and yaw bearings have been conducted using special test rig designed for the test of large slewing bearings. Test type was fatigue test that applied fatigue load to each bearing and followed the defined test process. Measurement data during test were rotational torque and raceway temperature, and inspected key components by disassembling the bearing after all test finished. As a results, the raceway temperature during test did not exceed the operational temperature range of lubricant and rotational torque was reduced as the bearing's rotational cycle increased. In the inspection of key components, some plastic deformation and flaking were detected at some raceway sections while other components such as ball, spacer and seal remain indefective conditions.

• Tribology and Lubricants
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• 제39권2호
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• pp.76-80
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• 2023

This paper describes an experimental investigation of the effect of cooling flow rate on gas foil thrust bearing (GFTB) performance. In a newly developed GFTB test rig, a non-contact type pneumatic cylinder provides static loads to the test GFTB and a high-speed motor rotates a thrust runner up to the maximum speed of 80 krpm. Force sensor, torque arm connected to another force sensor, and thermocouples measures the applied static load, drag torque, and bearing temperature, respectively, for cooling flow rates of 0, 25, and 50 LPM at static loads of 50, 100, and 150 N. The test GFTB with the outer radius of 31.5 mm has six top foils supported on bump foil structures. During the series of tests, the transient responses of the bearing drag torque and bearing temperature are recorded until the bearing temperature converges with time for each cooling flow rate and static load. The test data show that the converged temperature decreases with increasing cooling flow rate and increases with increasing static load. The drag torque and friction coefficient decrease with increasing cooling flow rate, which may be attributed to the decrease in viscosity and lubricant (air) temperature. These test results suggest that an increase in cooling flow rate improves GFTB performance.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.199-206
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• 2002

This paper describes a reliability characteristics of an air foil journal bearing for high speed turbomachinery at room temperature. To verify the reliability of air foil journal bearing, lift-off characteristics, load carrying capacity, and 10,000 cycle start-stop test were performed with motor driven test rig. Lift-off test shows the relationship between the rotating speed of the shaft and the frictional torque with bearing surface. About load carrying capacity, the tested air foil journal bearing produced a load capacity of 500N at an operating speed of 15,000rpm, which is compared with results of numerical analysis and empirical coefficients. Finally, The trends in change of start torque, stop torque, and bearing temperature were shown during 10,000 cycle start-stop test of an air foil journal bearing. from the results of this work, an air foil bearing will be done well, as a supported bearing for high speed turbo-compressor.

• 한국유체기계학회 논문집
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• 제6권2호
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• pp.7-14
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• 2003

This paper describes reliability characteristics of an air foil journal bearing for high-speed turbomachinery at a room temperature. To verify the reliability of air foil journal bearing, lift-off characteristics, load carrying capacity, and 10,000 cycle start-stop test were performed with a motor-driven test rig. A lift-off test shows the relationship between the rotating speed of the shaft and the frictional torque with bearing surface. About a load-carrying capacity, the tested air foil journal bearing produced a load capacity of 500N at an operating speed of 15,000rpm, which is compared with results of numerical analysis and empirical coefficients. Finally, the trends in change of start torque, stop torque, and bearing temperature were shown during a 10,000-cycle start-stop test of an air foil journal bearing. We found that an air foil bearing performs well, as a supported bearing for the high-speed turbocompressor.

• Tribology and Lubricants
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• 제34권5호
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• pp.183-190
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• 2018

Tilting pad journal bearing is widely used for steam turbines because of its excellent dynamic stability. As the turbine capacity increases, power loss in the bearings becomes a matter of concern. Power loss in tilting pad journal bearings can be reduced by increasing the bearing clearance and reducing the pad arc length. In this study, the tilting pad journal bearing is tested by changing the seal tooth clearance to verify the static characteristics of the bearing. Bearing power loss and bearing metal temperature are evaluated to compare the bearing's performance and reliability for several test cases. The test bearing is a tilting pad journal bearing with 300.62mm inner diameter and 120.00mm active length. The bearing power loss, its metal temperature, and oil film thickness are measured and evaluated based on the rotor's rotational speed, oil flow rate, and bearing load. Test results show that a tilting pad journal bearing with large seal tooth clearance has 40% lower power loss compared with a bearing with a small seal tooth clearance. As the seal tooth clearance is increased, the power loss of the tilting pad journal bearing decreases. However, with respect to the bearing metal temperatures, a detuning point is observed that makes the minimum bearing metal temperature. Moreover, as the seal tooth clearance is increased, the oil film thickness increases due to high viscosity.

• Steel and Composite Structures
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• 제41권5호
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• pp.731-746
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• 2021

The purpose of this paper is to investigate the axial bearing capacity and residual properties of steel reinforced recycled aggregate concrete (SRC) column after elevated temperature. A total of 48 SRC columns were designed for the static loading test after elevated temperature. The variables include replacement ratios, designed temperature, target duration, thicknesses of cover concrete, steel ratios and stirrup spacing. From this test, the mass loss ratio and stress load-deformation curve were obtained, and the influence of various parameters on residual bearing capacity were analyzed. ABAQUS was used to calculate the temperature field of specimens, and then got temperature damage distribution on the cross-section concrete. It was shown that increasing of the elevated temperatures leaded to the change of concrete color from smoky-gray to grayish brown and results in reducing the bearing capacity of SRC columns. The axial damage and mechanism of SRC columns were similar to those of reinforced natural aggregate concrete columns at the same temperatures. Finally, the calculation method of axial compressive residual bearing capacity of SRC columns recycled concrete columns after high temperature was reported based on the test results and finite element analysis.

• Tribology and Lubricants
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• 제18권2호
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• pp.153-159
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• 2002

This paper describes a durability characteristics of an air-lubricated bump foil journal bearing for high speed turbomachinerys at room temperature. At first, lift-off test and load capacity test were performed to understand the general characteristics of an air-lubricated bump foil Journal bearing. A 52 N weighted bump foil bearing sleeve was lilted off from a rotating Journal at about 3,000 rpm, and produced a load capacity of 500 N at an operating speed of 15,000 rpm. The next was 500 cycles lift-off test with an air-lubricated bump foil journal bearing that had a molybdenum disulfide(MoS$_2$) solid lubricant coated top foil. Data from measuring bearing torque and temperature and the observation of rubbing surfAce were included in results. Therefore the results of this work will aid in proving durability of air-lubricated bump foil journal bearings.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.212-219
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• 2001

This paper describes a durability characteristics of an air-lubricated bump foil journal bearing for high speed turbomachinerys at room temperature. At first, lift-off test and load capacity test were performed to understand the general characteristics of an air-lubricated bump foil journal bearing. A 52N weighted bump foil bearing sleeve was lifted off from a rotating journal at about 3,000rpm, and produced a load capacity of 500N at an operating speed of 15,000rpm. The next was 500 cycles lift-off test with an air-lubricated bump foil journal bearing that had a molybdenum disulfide(MoS$_2$) solid lubricant coated top foil. Data from measuring bearing torque and temperature and the observation of rubbing surface were included in results. Therefore the results of this work will aid in proving durability of air-lubricated bump foil journal bearings.

• Earthquakes and Structures
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• 제6권2호
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• pp.127-140
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• 2014

Laminated rubber bearing is very popular base isolation of earthquake engineering pertaining to the passive structural vibration control technologies. Rubber used in fabricating NRB and LRB can be easily attacked by various environmental factors such as oxygen, heat, light, dynamic strain, and organic liquids. Among these factors, this study carried out thermal aging test to investigate the effect of thermal aging on the mechanical properties of laminated rubber bearings in accelerated exposure condition of $70^{\circ}C$ temperature for 168 hours. The compressive-shear test was carried out to identify the variation of compressive and shear properties of the rubber bearings before and after thermal aging. In contrast to tensile strength and elongation tests, the hardness of rubber materials showed the increasing tendency dependent on exposure temperature and period. Based on the test results, the property changes of rubber bearing mainly aged by heat are quantitatively presented.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.497-504
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• 2005

This paper presents the results of experimental studies on the equipment isolation effect considering the floor response. For this purpose, shaking table tests were performed. For the measuring the floor response, numerical analysis was performed. For the isolation for the equipment, Natural Rubber Bearing(NRB), High Damping Rubber Bearing(HDRB) and Friction Pendulum System(FPS) were used. Finally, it is presented that the isolation systems used in this test can be adopted for the small equipment isolation. But the rubber bearing used in this study affected to the temperature change very sensitively.