• Title/Summary/Keyword: connecting rod small end

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Failure Analysis of Connecting Rod at Small End (커넥팅로드 소단부 파단의 해석)

  • 민동균;전병희;김낙수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.382-390
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    • 1995
  • Failure of connecting rod in automotive engine may cause catastrophic situation. The corner radius at small end has an effect on stress raising. To investigate the stress distribution in connecting rod during operation, the finite element analysis was used by giving possible maximum tension and compression. Excessive sizing after forging connecting rod may result in the tensile residual stress which lower the fatigue life and cause premature failures. It was shown that when the sizing amount is too large, the location of high tensile residual stress coincide with that of high stress amplitude during operation through the elastic-plastic finite element analysis. The endurance limit moves down due to the surface finish and decarburization, which combines with the movement of resultant stress points to dangerous range. It was concluded that the precise control of sizing and enough corner radius are necessary to a reliability of connecting rod.

Wear Analysis at the Interface of Connecting-Rod Small-End Bushing and Piston-Pin Boss with a Floating Piston-Pin at Constant Angular Velocity during Engine Firing (엔진 파이어링동안 일정 축 각속도에서 비고정식 피스톤-핀과 연결봉-소단부 부싱 및 피스톤-핀 보스의 접촉면 마모해석)

  • Chun, Sang Myung
    • Tribology and Lubricants
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    • v.36 no.3
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    • pp.168-192
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    • 2020
  • In recently designed diesel engines, the running conditions for piston-pin bearings have become severe because of the higher combustion pressure and increased temperature. Moreover, the metal removal from the bushing material has strongly reduced the ability of the antifriction material to accept asperity contacts. Therefore, it is necessary to find ways of reducing wear scar on the connecting-rod small-end bushing and piston-pin boss bearing related to the higher combustion pressure on the power cell of an engine. In this work, the position and level of material removal from the surfaces of the bushing and bearing under such severe operating conditions - for example, maximum power and torque conditions of a passenger car diesel engine - are estimated for several combinations of surface roughness. First, piston-pin rotating motion is investigated by calculating the friction coefficient at piston-pin bearings, the oil film thickness, and the frictional torques induced by hydrodynamic shear stress. Subsequently, the wear scarring on the surfaces of a connecting-rod small-end bushing and two piston-pin boss bearings related to piston-pin rotational motion is numerically calculated under the maximum power and torque operating conditions. This work is helpful to determine the reasonable surface roughness of the bushing and bearing for reducing wear volume occurring at the interface between a bearing and a shaft.

Robust Design of Connecting Rod (커넥팅로드 강건 설계 방안)

  • Han, Moonsik;Yang, Chulho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.1
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    • pp.142-147
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    • 2014
  • Finite element analysis along with DOE scheme has been performed to obtain robust design of connecting rod assembly. An analysis was conducted with five loading steps. Fatigue analysis was done using commercial software FEMFAT and fatigue safety factors at the interested regions such as shank area of small end and big end were calculated. 27 design cases using 3 factors with 3 levels are constructed by design of experiment. Each case is simulated to find the most influential factors. Response for this study, maximum Von-Mises stress, has been used to determine main factors of connecting rod assembly. Among the 3 factors, compression load affected the response greatly. However, bolt assembly load and width of shank flat area showed a little influence to the response. Interaction effects among factors considered did not occur. Connecting rod assembly considered in this study showed its sensitivity to the noise factor such as compression load rather than design factor such as width of flat shank area.

Robust Design of Connecting Rod Using Variable Stress (변동 응력을 이용한 커넥팅 로드 강건 설계)

  • Lee, Seungwoo;Kim, Hangyu;Lee, Taehyun;Yang, Chulho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.6
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    • pp.716-723
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    • 2016
  • A connecting rod is a crucial part for transmitting an explosive force to the crankshaft in the engine. Stress concentration in connecting rod due to the accumulation of the repeated load may initiate micro crack and result in a crucial break down of the component. Two approaches are adopted to obtain a robust design of connecting rod. Inner and outer array matrix based on combinations of control factors and noise factors are constructed for using Taguchi method. Calculated stress results for each element of matrix are plotted in the Goodman diagram. Robust design approach by Taguchi method reduces stress concentration occurred in small end fillet area of the default model. Variable stress approach using Goodman diagram also confirms a robust design by Taguchi method.

An experimental study on friction measurement of piston-ring assembly of a SI engine (가솔린 기관의 피스톤-링 결합체 마찰력 측정에 관한 실험적 연구)

  • 이동원;윤정의;김승수
    • Journal of the korean Society of Automotive Engineers
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    • v.12 no.4
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    • pp.66-74
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    • 1990
  • Friction between piston-ring assembly and cylinder wall of a spark ignition engine was evaluated under various engine operating conditions utilizing a grasshopper linkage system. The friction force was estimated by the force balance relation at the small end of connecting rod. Three forces were chosen to be measured for the objective. They were gas pressure inside the cylinder, inertia force of the piston-ring assembly, and the force exerted by the connecting rod. These forces were measured by a piezo type pressure sensor, an accelerometer and strain gauges, respectively. Comparisons were made with the frictional force evaluated by the conventional method where the assumption of constant rotational speed of engines was adopted. Due to the variation of rotational speed of engines, the conventional method was found to lead to a large error in the evaluation of the frictional force.

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Simulation of the Initial Wear and Lubrication Performance of Marine Engine Components (선박엔진 부품의 성능 향상을 위한 초기 마모 및 윤활 해석 연구)

  • Cha, Su-Bin;Lee, Hyang;Chung, Koo-Hyun
    • Tribology and Lubricants
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    • v.38 no.6
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    • pp.227-234
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    • 2022
  • Recently, the demand for improving energy efficiency has rapidly increased because of the growing concerns over environmental issues. In this work, the tribo-test and simulation for the initial wear and lubrication performance were performed for the piston pin in the small end system of the connecting rod of a marine engine, to obtain useful data for improving the efficiency of marine engine systems. In addition, a diamond-like carbon (DLC) coating was applied to the piston pin to explore feasibility of eliminating the bush used in the system. The initial wear and lubrication characteristics between the uncoated piston pin and bush were compared with that between the DLC-coated piston pin and connecting rod in the tribo-test. The simulation for the wear and lubrication performance according to the wear progression was conducted based on the data obtained from the test. The wear characteristics were quantitatively assessed by the wear depth and wear volume, and the lubrication performance was characterized with the change of pressure and minimum oil film thickness with respect to the crank angle. It was found that the DLC-coated piston pin may provide better initial wear characteristics and lubrication performance. The results of this work may provide fundamental information for marine engines with improved efficiency.

Study on the Rotating Motion of a Piston Pin of Full Floating Type (비고정식 피스톤 핀의 회전운동에 관한 연구)

  • Chun, Sang-Myung
    • Tribology and Lubricants
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    • v.23 no.3
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    • pp.95-102
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    • 2007
  • In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. Moreover, the lead removal from the bush material has strongly reduced the capability of the anti friction material to accept asperity contacts. In this paper, before trying to find the pressure distributions on the oil film of piston pin bearings by the unsteady two dimensional thermohydrodynamic lubrication analysis in order to do the optimum design of the bearings of piston pin, it will be investigated the tendancy of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress.

Pin-Boss Bearing Lubrication Analysis of a Diesel Engine Piston Receiving High Combustion Pressure (고 연소압을 받는 디젤엔진 피스톤의 핀-보스 베어링 윤활해석)

  • Chun, Sang-Myung;Ha, Dae-Hong
    • Tribology and Lubricants
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    • v.24 no.3
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    • pp.133-139
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    • 2008
  • In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated the effects on the film pressure distribution due to the change in maximum combustion pressure.

A Study on Effects of the Changes in Lower Combustion Pressures and Pressure-Viscosity Index on Pin-Boss Bearing Lubrication of a Diesel Engine Piston Receiving High Combustion Pressure (연소실 저압변화와 압력-점도지수가 디젤엔진 고압피스톤의 핀-보스 베어링 윤활에 미치는 영향 연구)

  • Chun, Sang-Myung
    • Tribology and Lubricants
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    • v.24 no.2
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    • pp.55-62
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    • 2008
  • In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated how the changes in combustion pressure at exhaust and intake stroke and the pressure-viscosity index effect on the film pressure distribution.

Pin-Boss Stress Analysis Coupled with Oil Film Pressure of a Diesel Engine Piston Receiving 200 bar Combustion Pressure (200 bar 연소압을 받는 디젤엔진 피스톤 핀-보스의 유막 압력을 고려한 응력해석)

  • Chun, Sang-Myung;Lee, J.S.;Joo, D.H.;Park, S.J.
    • Tribology and Lubricants
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    • v.24 no.4
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    • pp.196-204
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    • 2008
  • In this study, the pressure distributions on the oil film of piston pin bearings are found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. The lubrication analysis is carried out together with an equation related with the oil pressure-viscosity index. The oil film pressure distribution is used as an input data for pressure boundary conditions at the piston pin-boss surface. Finally, the piston pin-boss stress distribution coupled with the thermal stress is calculated, and then compared with the results of the stress analysis which is not counted with the oil film pressure boundary condition.