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틸팅 패드 베어링의 트라이볼로지 특성 평가를 위한 유막두께 측정 방법 연구
김미루(Mi-Ru Kim),이득우(Deug-Woo Lee),이승준(Seung-Jun Lee),시티 누르파딜라 빈티 자이니(Siti Nurfadilah Binti Jaini),정재호(Jae-Ho Jung) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.5
In studies on lubrication analyses, researchers have investigated mixed lubrication as well as hydrodynamic lubrication. One of these published studies concerns lubrication analysis by considering not only the surface roughness but also the slope parameter of the friction surface; in the study, the relative slope of the pad bearing surface was confirmed to influence the friction characteristics. However, verification of whether the lubrication analysis values are comparable to those of the friction tests is yet to be conducted. In this study, to experimentally verify the results of this previous lubrication analysis, we developed an experimental device to derive the slope parameter and analyzed the results. The film thickness was calculated by analyzing the slope parameter obtained from the friction tests and was then used as the input value for lubrication analysis.
Potential energy savings of air lubrication technology on merchant ships
Kim Young-Rong,Steen Sverre 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-
As the reduction of greenhouse gas emissions has become an important issue, measures and devices to reduce energy consumption are in increasing demand. In this study, the potential energy saving due to the application of air lubrication technology in merchant ships is analyzed. We propose a simplified empirical model, covering three different air lubrication technologies, based on the experimental results and assumptions taken in the existing studies. The bottom surface area covered with air is important for the efficiency of the air lubrication system, according to the sensitivity analysis. From the global fleet analysis, net-percentage power saving varies according to the operational profile as well as the technology. Net-percentage power savings of 2e5% from air bubble, 8e14% from air layer, and 16e22% from air cavity technology were obtained assuming calm-water conditions. The methodology can be adopted in early design stage and fleet-wide analyses of various energy-saving measures.
조성찬(Sungchan Cho) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The characteristics of whole engine lubrication network are influenced by bearing dynamic behavior. This paper presents a numerical study to investigate the effects of connecting rod bearing deformation by bolt pretension, rotating and reciprocating inertia and cylinder pressure. 1-D system analysis was conducted for whole lubrication network analysis while the bearing deformation analysis results were obtained by structure analysis. Oil flow through bearing was calculated by FVM analysis. Oil pressure drop and oil flow variance under different load cases were compared each other.
이필호,이상원,Se-Hwa Lim,이수홍,고한서,신승원 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.9
The objective of this study was to investigate the thermal characteristics of a micro-scale grinding process using nanofluid minimum quantity lubrication (MQL) with experimental and numerical analyses. In the experimental analysis, a series of micro-scale grinding experiments were conducted with the miniaturized machine tool system, and the sub-surface grinding temperatures and tangential grinding forces were measured with an embedded thermocouple and a load cell, respectively. For numerical analysis, a computational fluid dynamics (CFD) approach was adopted to build a new thermal and flow model for the micro-scale grinding process with consideration of the input heat flux, while the grinding energy partition was also estimated using a response surface method (RSM). The grinding temperatures estimated from the numerical analysis displayed good agreement with experimental values, thus validating the proposed thermal model. The grinding temperatures, grinding heat flux into the workpiece and grinding energy partition under the nanofluid MQL were also found to be much lower than those in the cases of compressed air lubrication and pure MQL.
마이크로 버블 발생장치와 결합된 오일 플러싱 장치 개발
홍성호,이경희,정남화 한국트라이볼로지학회 2022 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.38 No.3
This paper reports the development of an oil flushing system combined with a microbubble generator. Oil flushing plays a crucial role in regulating the lubricant’s performance during the lubricant replacement process. Moreover, harmful contaminants, such as sludge, wear particles, and rust, from piping systems or lubrication system can be removed by oil flushing. Oil flushing aims to increase the system’s efficiency using a dedicated flushing oil, increasing of the supply pressure and generating a vortex. In addition, it helps the mechanical system or equipment achieve peak performance and reduces the potential for premature failure. However, the contaminant-removal applications of existing oil flushing system are limited. In this research, we aim to improve the performance of oil flushing system by incorporating a microbubble generator, which uses the venture effect to generate microbubbles and mixes them with lubricant. The microbubbles in the blended lubricant remove contaminants from the lubrication system more effectively. Structural mechanics and fluid dynamics are analyzed through fluid-structure interaction (FSI) analysis, and the numerical analysis results are used for the designing the system. The magnitude of the maximum stress is investigated based on the pressure results obtained by the CFD analysis; through the CFD analysis, the mixing ratio of air (bubble) and lubricant is evaluated using the volume of fluid (VOF) model according to the working conditions.
이안성(An Sung Lee),이동환(Dong Whan Lee),나언주(Uhn Joo Na) 한국트라이볼로지학회 2003 한국트라이볼로지학회 학술대회 Vol.36 No.-
In high-speed gas-levitation applications a high compressibility number often brings a numerical difficulty in predicting generated pressure profiles by causing erroneous sudden pressure overshootings and oscillations in the trailing-edge. To treat the problem, in this study an exact exponential high-order shape function is introduced in the FE lubrication analyses. It is, shown by various examples that the high-order shape function scheme can subdue successfully pressure overshootings and oscillations.
열처리 생략강의 인발특성 향상을 위한 윤활제와 피막제의 기계적 거동 고찰
이상준(Sang-Jun Lee),유위경(Ui-Kyung Yoo),이영석(Young-Seog Lee),변상민(Sang-Min Byon) 한국기계가공학회 2008 한국기계가공학회지 Vol.7 No.4
In this research, we developed a pilot wire-drawing machine as well as wire end-pointing roller. Using these machines, we performed a pilot wire-drawing test at different coating material and lubricant when the reduction ratio is 10 %. To inversely compute the friction coefficient between the coating layer of wire and the surface of die for a specific lubricant, we carried out a series of three dimensional finite element analysis. Results show that the drawing force is varied with the coating material of wire at the same reduction ratio and lubricant. It is noted that the frictional coefficient in drawing is dependent on the coupled property of coating material and lubricant, indicating the best coating material for a given lubricant.
김영창(Young Chang Kim),김진우(Jin Woo Kim),김정섭(Jung Sub Kim),이상원(Sang Won Lee) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.5
This paper discusses flow characteristics of nanofluid minimum quantity lubrication (MQL) in the milling process of a titanium alloy by usingnumerical analysis. A mist of nanofluids including nanodiamond and hexagonal boron nitride (hBN) particles is sprayed into a tool-workpiece interface with conditions varying by spray angle and flow rate. The milling. Are experimentally measured and minimized by the determined optimal spray angle and flow rate. The subsequent numerical analysis based on a computational fluid dynamics (CFD) approach is conducted to calculate the penetration ratios of the nanofluid droplets into a tool. At the experimentally obtained optimal spray angle and flow rate of the nanofluids’ mist, the calculated ratio of penetration is highest and, therefore, the optimal spray conditions of the nanofluids are numerically validated.
Multiscale Interface Stress Characterisation in Cold Rolling
Chuhan Wu,Liangchi Zhang,Peilei Qu,Shanqing Li,Zhenglian Jiang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
This paper provides a comprehensive review on the multiscale characterisation of interface stresses in cold rolling considering both the random asperity deformation and lubrication. The characterisation of the microscopic interface friction wasanalysed with the efects of lubricant shearing, asperity sliding, lubricant additives and oil-in-water emulsion. Multiscalemodelling of rolling under diferent lubrication regimes was discussed in detail. Some open problems for further studieswere also summarised.
탄소성 유한요소법을 이용한 드로우비드 성형 및 인발공정 해석
정동원,이상제 濟州大學校 工科大學 産業技術硏究所 1998 尖端技術硏究所論文集 Vol.9 No.1
During the sheet metal forming, it is often necessary to control the rate of metal flow into the die cavity. The control of metal flow can be achieved through the blankholder, lubricant, draw-bead, or a combination. In this study among the conditions, examines the draw-bead. The role of control or restraining beads is to provide enough tension to deform the material plastically over the punch face, and to ensure proper shape fixing of the part. In this study, an elasto-plastic/static-implicit FE program is used for the analysis. It was assumed the result of numerical analysis is applicable to the practical industrial process by analyzing the draw-bead forming and traction process with erection.