• Transactions of the Korean Society of Machine Tool Engineers
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• 제10권1호
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• pp.65-70
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• 2001

The hear transfer mechanism initiating the friction welding is examined and a transient three dimensional heat conduc-tion model for the welding of two dissimilar cylindrical metal bars is investigated. The cylindrical metal bars are made of materials made of A2024 and SM 45C. Numerical simulations of heat flow are performed using the finite volume method. Respectively. Commercial FLUENT code is used in the heat flow simulation and maximum temperature and distribution of temperature are calculated. Temperature of friction welded joining face is compared with the temperature distribution measured by experiment and numerical simulation. The maximum temperature of friction welded joining face is lower than melting point of A2024-T6 aluminum alloy using insert metal. The temperature distribution of friction welded join- ing face with insert metal is more uniform than that of without inset metal.

• Journal of the Korean Society for Precision Engineering
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• 제22권6호
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• pp.159-167
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• 2005

This work focuses on the effects of crack free friction on Mode II stress intensity factors, $K_{II}$, for a vertical surface crack in a two-dimensional finite element model of TiN/steel subject to rolling contact. Results indicate that maximum $K_{II}$ values, which occur when the load is adjacent to the crack, may be significantly reduced in the presence of crack face friction. The reduction is more significant for thick coatings than for thin. Crack extension and increased layer thickness result in increased $K_{II}$ values. The effect of crack face friction on compressive $K_I$ values appears negligible. Comparative results are presented for $MoS_2/steel$ and diamond-like carbon(DLC)/Ti systems.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.341-349
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• 2001

Heat distortion of the non-contacting mechanical face seal is affected by friction heat between primary seal and seal sheet. The fluid or gas in mechanical face seal maintains operating gap, cooling friction heat and lubricates at the face of seal. So we designed face of seal for inclined face. inclined face of seal improves fluid or gas flow at the face of seal and it increases circumferential velocity at outer radius of the seal so temperature of the seal is decreased by low heat transfer coefficient at there. In this paper, inclined face seal are analysed numerically using finite element method for proof improve inclined face seal performance. Angle of the incline face used for FEA is from 50$^{\circ}$to 90$^{\circ}$and for explaining the effects of inclined face in seal, we get temperature, face distortion, and stress in the seal with variable operating gap and rotating speeds. Result of analysis shows that angle of the incline face is 60$^{\circ}$come to good thermal distortion characteristics.

• Tribology and Lubricants
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• 제27권5호
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• pp.240-248
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• 2011

Mechanical face seal installed in primary heat transport pump used for heavy water reactor prevents leakage of working fluid using thin working fluid film between primary seal ring and mating ring. If the leakage of working fluid exceeds the allowable volume, serious accident can be happened by the trouble of primary heat transport pump. The thinner fluid film exists between primary seal ring and mating ring, the less working fluid leaks out. On the other hand, if the thickness of fluid film is not enough, the life of mechanical face seal will be reduced by friction and wear. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the performance of mechanical face seals which have same deep straight groove and 11 different net coning values. As results, equilibrium clearance between primary seal ring and mating ring, leakage volume of working fluid, friction torque on sealing surface and stiffness of working fluid film were obtained. With increasing net coning value, equilibrium clearance and leakage volume increase, and friction torque and stiffness of fluid film decrease.

• Tribology and Lubricants
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• 제26권4호
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• pp.230-239
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• 2010

Mechanical face seal installed in boiler feedwater pump prevents leakage of working fluid using thin fluid film between stator and rotor. If the leakage of working fluid exceeds the allowable volume, serious malfunction of boiler feedwater pump will be happen. The thinner fluid film exists between stator and rotor, the less working fluid leaks out. However, if the thickness of fluid film is not enough, the wear of seal face will be increased. And it causes the decrease in life of mechanical face seal. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the static characteristics of wavy mechanical face seals which have 4 different wavy surface profiles on rotor. As a result, opening force, leakage volume of working fluid and friction torque were obtained. For the same minimum film thickness, the static characteristics of mechanical face seal were affected by the wavy surface profile which can change the thickness of working fluid film and pressure distribution.

• Journal of the Korean Geotechnical Society
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• 제35권12호
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• pp.7-13
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• 2019

In the case of the drilled shaft, one of the methods for calculating unit skin friction stress of rock socket parts is to measure the roughness of the excavated face. This method is to estimate the unit skin frictional resistance using a device which measures the roughness shape of the excavated face in the excavation step. In this study, the roughness shapes of the face of the rock socket part in the drilled shaft were measured directly in the perforated hole and the results are used to identify the characteristics of the unit skin friction of the bedrock. In addition, the static load test and the load transfer test were performed on the same pile to verify the result of the roughness test.

• Tribology and Lubricants
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• 제20권6호
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• pp.314-321
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• 2004

Thermal distortion of non-contacting mechanical seals with inclined rubbing surfaces is affected by friction heat between seal ring and seal seat. The circulation fluid along the inclined rubbing surfaces maintains cooling friction heat and lubrication between the sealing surfaces of mechanical seal with an inclined surface. Mechanical seals with inclined sealing surfaces may be useful for reducing the frictional heating and power loss because of the introduction of cooling fluids to the sealing gap between seal ring and seal seat. From the FEM computed result shows that the thermal behavior and von Mises stress of sealing faces with an inclined angle 60 are much reduced in comparison of the conventional mechanical face seal with rectangular sealing surfaces.

• Tribology and Lubricants
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• 제19권5호
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• pp.274-279
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• 2003

$Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.

• Tribology and Lubricants
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• 제28권2호
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• pp.70-80
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• 2012

Non-contact type mechanical face seals installed in mechanical systems prevent leakage of working fluid using thin working fluid film between stator and rotor. For that purpose, various kinds of surface profiles, grooves and conings have been applied on seal surfaces of stator and rotor to generate hydrodynamic and hydrostatic pressure. The thickness distribution of working fluid film is one of important factors which affect the working performances of mechanical face seal, and it is strongly affected by the surface height profiles of stator and rotor. Therefore, appropriate design of surface height profiles of stator and rotor is necessary to optimize the working performances and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to estimate the working performances of wavy mechanical face seals which have 36 coning combinations. As results, minimum thickness of working fluid film, leakage volume of working fluid and friction torque in static equilibrium condition of mechanical face seal, and stiffness of working fluid film were obtained. The results show that the working performances of mechanical face seal were affected by the coning combinations which can change the thickness distribution of working fluid film and pressure distribution in sealing region of mechanical face seal.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.457-464
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• 2000

Stereographic method is a general and basic method to analyse sliding failure potential of rock slope. Region of failure analysis using stereographic method extend to curved slope from straight slope in this paper, Curved slope is defined as the multi-face slope with free surface more than two face and has different characteristics from straight single face slope. Individual daylight envelopes of free surfaces are combined into total daylight envelope of multi-face slope. So, sliding envelope of multi-face slope is the daylight envelope except friction cone. Specially, If only single joint set is developed in the slope, single plane sliding(or plane failure) is impossible in the single-face straight slope, but possible in the multi-face slope. In the multi-face slope with only one joint set, single plane sliding occurs when orientation of sliding plane is between two side slope orientation in the sliding envelope.