• Title/Summary/Keyword: 마찰 모델

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Interrelationship Between the Drift-flux Model and the Two-fluid Model (드리프트 플럭스 모델과 2-유체 모델 사이의 상관 관계)

  • No, Hee-Cheon
    • Nuclear Engineering and Technology
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    • v.25 no.2
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    • pp.233-236
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    • 1993
  • For one-dimensional two-phase flow without phase change and without axially-temporally rapid change of pressure, the interrelationship between the drift-flux model and the two-fluid model is studied. It is derived on the basis of the fact that the vapor conservation equation is related to the momentum equation by the drift flux. Starting from the two-fluid model, we obtain the interfacial friction expressed in terms of drift-flux parameter. Also, by deriving the void propagation equation, the drift-flux is shown to have jnterrelationship with forces in the two-fluid model.

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Prediction methods for two-phase flow frictional pressure drop of FC-72 in parallel micro-channels (병렬 마이크로 채널에서 FC-72의 2상 유동 마찰 압력 강하 예측)

  • Choi, Yong-Seok;Lim, Tae-Woo;You, Sam-Sang
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.7
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    • pp.821-827
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    • 2014
  • In this study, an experimental study was performed to predict the two-phase frictional pressure drop of FC-72 in parallel micro-channels. The parallel micro-channels consist of 15 channels with depth 0.2 mm, width 0.45 mm and length 60 mm. And tests were performed in the ranges of mass fluxes from 152.2 to $584.2kg/m^2s$ and heat fluxes from 7.5 to $28.3kW/m^2$. The experimental data was compared and analyzed with existing correlations to predict the pressure drop. The existing methods to predict the pressure drop used the homogeneous model and the separated model. In this study, the new correlation was proposed by modified existing correlation using the separated model, and the new correlation predicted consequently with the experimental data within MAE of 9.6%.

Friction-induced ignition and initiation modeling of HMX, RDX and AP based energetic materials (마찰 하중에 의한 HMX, RDX, AP기반 고에너지물질의 발화특성모델링 연구)

  • Gwak, Min-Cheol;Yoo, Ji-Chang;Yoh, Jai-Ick
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.11a
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    • pp.283-287
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    • 2008
  • The heat released during the external frictional motion is a factor responsible for initiating energetic materials under all types of mechanical stimuli including impact, drop, or penetration. We model the friction-induced ignition of HMX, RDX and AP/HTPB propellant using the BAM friction apparatus and one-dimensional time-to-explosion apparatus whose results are used to validate the friction ignition mechanism and the deflagration kinetics of energetic materials, respectively. The ignition times for each energetic sample due to friction are presented.

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Finite Element Analysis for Friction Noise with Respect to the Friction Curve of Several Materials (재질 별 마찰곡선을 반영한 마찰소음 유한요소 해석 연구)

  • Baek, Jongsu;Nam, Jaehyeon;Do, Hyuncheol;Kang, Jaeyoung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.5
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    • pp.449-455
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    • 2016
  • This study provides the finite-element (FE) squeal-model predicting friction-induced noise with respect to several friction materials that have different friction characteristics. The friction curve and the corresponding friction noise were measured for four friction materials (Cu, Ni, Al, Mg) using the pin-on-disk and reciprocating friction system. The slope of the friction curve linearized at the sliding velocity was applied to the FE model. The unstable modes in the complex eigenvalue analysis were shown to correspond to the squeal frequencies that existed in the experiment.

A Study of Friction in Microfoming Using Ring Compression Tests and Finite Element Analysis (링 압축시험과 유한요소해석을 이용한 미세성형 공정에서의 마찰특성에 관한 연구)

  • Kim, Hong-Seok;Kim, Geung-Rok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.10
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    • pp.1471-1478
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    • 2010
  • Microforming processes have recently attracted considerable attention from industry and academia since they enable the production of microscale parts using various materials at a high production rate, minimize material loss, and provide parts with excellent mechanical properties. However, for successful development and applications of the microforming process it is critical to take the tribological size effect into consideration because previous studies have shown that traditional friction models for macroscale forming generate significantly erroneous results in the case of microforming. In this paper, we performed scaled ring compression experiments to investigate the tribological size effect of aluminum and brass materials in microforming. The sensitivity of the interfacial friction to the deformation characteristics of the ring was quantitatively analyzed by the finite element analysis. In addition, a friction model based on slip line field and upper boundary techniques was used to theoretically explain the friction mechanism in microforming.

Modelling and Development of Control Algorithm of Endoscopy

  • Ma, Weichao;Lee, Sanghyuk
    • Journal of Convergence Society for SMB
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    • v.4 no.2
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    • pp.33-39
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    • 2014
  • In this paper, basic backgrounds about capsule endoscopy are introduced, and the aims and objectives are also illustrated. Methodology and mathematical model for LuGre model were investigated to analyse system characteristics. A nonlinear friction model, the stick-slip motion system based on LuGre friction model was used to simulate the motion of capsule endoscopy inside human body. Under the different situation, LuGre friction model was simulated by Matlab Simulink software. The entire cycle of motion and the influence of parameters towards to velocity are fully simulated.

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Effect of Shear Reinforcement and Compressive Stress on the Shear Friction Strength of Concrete (콘크리트의 전단마찰 내력에 대한 횡보강근 및 압축응력의 영향)

  • Hwnag, Yong-Ha;Yang, Keun-Hyeok
    • Journal of the Korea Concrete Institute
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    • v.28 no.4
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    • pp.419-426
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    • 2016
  • This study examined the effect of transverse reinforcement and compressive stress on the shear friction performance at the shear interface intersecting two structural elements with various concrete types. From the prepared 12 push-off test specimens, various characteristics at the interface were measured as follows: crack propagation, shear load-relative slip relationship, initial shear cracking strength, ultimate shear friction strength, and shear transfer capacity of transverse reinforcement. The configuration of transverse reinforcement and compressive strength of concrete insignificantly influenced the amount of relative slippage at the shear friction plane. With the increase of applied compressive stress, the shear friction capacity of concrete tended to increase proportionally, whereas the shear transfer capacity of transverse reinforcement decreased, which was insignificantly affected by the configuration type of transverse reinforcement. The empirical equations of AASHTO-LRFD and Mattock underestimate the shear friction strength of concrete, whereas Hwang and Yang model provides better reliability, indicating that the mean and standard deviation of the ratios between measured shear strengths and predictions are 1.02 and 0.23, respectively.

Quantitative Analysis of Friction Weld Strength by Acoustic Emission (AE법에 의한 마찰용접강도의 정량해석)

  • Oh, S. K.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.7 no.2
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    • pp.226-232
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    • 1983
  • 회전수를 용접변수로 했을 때 이종강봉 및 이종강관의 마찰용접에 있어서 소성변형중에 발생한 AE(acoustic emission)량과 용접후의 냉각중에 발생한 AE량의 총량을 측정해석하고, 용접표면상 에 0.635mmR의 반원 노치를 가공했을 때의 용접부 인장강도를 구하여, AE총량과 용접부강도와 의 상관관계실험식 모델을 만들었고, 이들과 관계계산식과의 비교 조사와 95%신뢰성을 검증하였 고, 이종강의 마찰용접 중에 용접강도와 품질을 검토관리할 수 있는 기본자료가 되게 하였다.

A Study on Development of Model Materials Showing Similar Flow Characteristics of Hot Mild Steel at Various Temperatures (고온 연강 유동특성을 상사하는 모델재료 개발에 관한 연구)

  • 이종헌;김영호;배원병;이원화
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.5
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    • pp.1161-1171
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    • 1993
  • Model materials are developed to achieve similarity of flow patterns for mild steels in forming processes at high temperatures. The model materials consist of pure plasticine and one or two additives such as resin and lanolin. To verify the similarity of flow patterns between physical modeling and compression of mild steels at high temperatures, ring and compression tests have been carried out with the developed-model materials at various strain rates, temperatures and lubricants. The test results are in good agreement with the flow patterns obtained from upsetting of a mild steel at high temperatures.

On the Modeling and Simulation of Friction for an Automotive Clutch (자동차 클러치의 마찰 모델과 시뮬레이션)

  • 이병수;이재천
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.2
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    • pp.116-125
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    • 2003
  • Four models for stick-slip friction are presented and are adopted for a numerical simulation study for a manual transmission clutch damper in idle mode. Meaning of parameters for friction models are explained and proper values are suggested. Also explained ate the reason why those specific values for the parameters are chosen. Preferable model for the clutch damper In Idle mode is discussed in terms of calculation efficiency and fidelity of the model based on real measured data. For clutch damper idle mode simulation studies, all four models perform equally well.