• Proceedings of the KSME Conference
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• 2005.11a
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• pp.112.2-112.2
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.203-204
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• 2009

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.442-453
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• 2003

This study investigates the safety assessment of the potential for fretting-wear damages on steam generator (SG) U-tubes caused by foreign object in operating nuclear power plants. The operating SG shell-side flow field conditions are obtained from three-dimensional SG flow calculation using the ATHOS3 code. Modal analyses are performed for the finite element modelings of U-tubes to get the natural frequency, corresponding mode shape and participation factor. The wear rate of U-tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted. Also, discussed in this study is the effect of the flow velocity and vibration of the tube on the remaining life of the tube.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.67-72
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• 2004

Fundamentally, slip displacement should be known to solve the problem related to the fretting wear. For this, methods for measuring the slip displacement range in the contact surface of the tube and the supports were introduced and analyzed in this study. Also the increment of the slip displacement during a cycle was calculated using the revised formulas. As a result, the slip displacement newly evaluated was much higher ($7{\sim}50$ times) than that previously evaluated especially in the case of the gap existence. This enables to explain the severe wear found when there was a gap between the tube and the supports.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.78-83
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• 1999

Fretting Wear Behavior and Characteristics were investigated with Inconel 690 tube which is used in Nuclear Power Plant. Fretting Wear Tester has been engaged in the study of characteristics on tube fretted induced to various factors, i.e. vibration amplitude, contact type, material properties load support geometry, environmental effect Test has been performed in air and at room temperature. Wear volume rate has been approximately estimated as a function of normal load.

• Tribology and Lubricants
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• v.22 no.1
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• pp.8-13
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• 2006

Sliding wear tests have been performed to evaluate the effect of normal load decrease on the wear depth of nuclear fuel rods in room temperature air. The objectives of this study are to quantitatively evaluate the supporting ability of spacer grid springs, to estimate the wear depth by using the contacting force decrease and to compare the wear behavior with increasing test cycles (up to $10^7$) at each spring condition. The result showed that the contacting load decrease depends on the spring shape and the applied slip amplitude. The estimated wear depth is smaller when compared with measured wear depth. Based on the test results, the wear mechanism, the role of wear debris layer and the spring shape effect were discussed.

• International Journal of Automotive Technology
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• v.7 no.1
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• pp.75-82
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• 2006

Fretting corrosion widely known as a degradation mechanism refers to the combination of fretting wear and corrosion such as oxidation. This paper critically reviews the works published previously on fretting corrosion of electrical connectors. Various experimental approaches such as testing machines, material selection, testing environments, acceleration testing techniques and preventing methods are addressed. Future research prospects are suggested.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.59-62
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• 2001

Flow induced vibration in steam generators has caused dynamic interactions between tubes and contacting materials resulting in fretting wear . Series of experiments have been performed to examine the wear properties of Inconel 690 steam generator tubes in various environmental conditions. For the present study, the test rig was designed to examine the fretting wear and rolling wear properties in high temperature(room temperature - 290。C) water. The test was performed at constant applied load and sliding distance to investigate the effect of test temperature on wear properties of the steam generator tube materials. To investigate the wear mechanism of material, the worn was observed using scanning electron microscopy. The weight loss increase at higher test temperature was caused by the decrease of water viscosity and the mechanical property change of tube material. The mechanical property changes of steam generator tube material, such as decrease of hardness or yield stress in the high temperature tests. From the SEM observation of worn surfaces, the severe wear scars were observed in specimens tested at the higher temperature.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.256-261
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• 2004

To evaluate the effect of spring shape on the fretting wear of nuclear fuel rod, sliding wear tests were performed using three kinds of space grid springs in room temperature air and water. With increasing slip amplitude, wear volume of each spring gradually increased. It is apparently shown that spring with convex shape had a relatively high wear resistance compared with concave shape springs. It is suggested that the ratio of the wear volume to the worn area can be suggested as an efficient and valid parameter to evaluate the wear resistibility of a fuel grid spring.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.6 s.261
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• pp.701-709
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• 2007

To clarify the characteristics of surface damage due to fretting in press-fitted shaft, experimental methods were applied to small scale specimen with different bending load condition. Fatigue tests and interrupted fatigue tests of press-fitted specimen were carried out by rotate bending fatigue test. Macroscopic and microscopic characteristics were examined using scanning electron microscope (SEM), optical microscope or profilometer. It is found that small fatigue cracks are nucleated early in life regardless of bending stress, and thus the most portion of fatigue life on press fits can be considered to be crack propagation process. Most of surface cracks are initiated near the contact edge, and multiple cracks are nucleated and interconnected. Furthermore, the fretting wear rates at the contact edge are increased rapidly at the initial stage of total fatigue life. It is thus suggested that the fatigue crack nucleation and propagation process is strongly related to the evolution of surface profile by fretting wear in press fits.