• Title/Summary/Keyword: surface roughness model

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The Prediction of Rubber Friction considering Road Characteristics (노면 특성을 고려한 고무 마찰 예측 연구)

  • Nam, Seungkuk;Oh, Yumrak;Jeon, Seonghee
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.4
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    • pp.105-110
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    • 2014
  • This paper presents the hysteresis friction of a sliding elastomer on various types of surfaces. The hysteresis friction is calculated by means of an analytical model which considers the energy spent by the local deformation of the rubber due to surface asperities. By establishing the fractal character of the surfaces, the contribution to rubber friction of roughness at different length scales is accounted for. High resolution surface profilometer is used in order to calculate the main three surface descriptors and the minimal length scale that can contribute to hysteresis friction. The results show that this friction prediction can be used in order to characterize in an elegant manner the surface morphology of various surfaces and to quantify the friction coefficient of sliding rubber as a function of surface roughness, load and speed.

Analysis of the Influence of Electrical Discharge Machining Parameters on Surface Roughness of CK45

  • Abedi, Esmail;Daneshmand, Saeed;Karimi, Iman;Neyestanak, A. A. Lotfi
    • Journal of Electrochemical Science and Technology
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    • v.6 no.4
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    • pp.131-138
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    • 2015
  • Electrical discharge machining is an unconventional machining process in which successive sparks applied to machine the electrically conductive materials. Any changes in electrical discharge machining parameters lead to the pieces with distinct surface roughness. The electrical discharge machining process is well applied for high hardness materials or when it is difficult to use traditional techniques to do material removing. Furthermore, this method is widely applied in industries such as aerospace, automobile, molding, and tool making. CK45 is one of the important steels in industrial and electrical discharge machining can be considered as a proper way for its machining because of high hardness of CK45 after thermal operation of the electrical discharge machining process. Optimization of surface roughness as an output parameters as well as electrical discharge machining parameters including current, voltage and frequency for electrical discharge machining of CK45 has been studied using copper tools and kerosene as the dielectric. For such a purpose and to achieve the precise statistical analysis of the experiment results design of experiment was applied while non linear regression method was chosen to assess the response of surface roughness. Then, the results were analyzed by means of ANOVA method and machining parameters with more effects on the desired outputs were determined. Finally, mathematical model obtained for surface roughness.

Study of Mass and Flow Resistance in a Square Ribbed Microchannel using Lattice Boltzmann Method

  • Taher, Mohammad Abu;Kim, Heuy-Dong;Lee, Yeon-Won
    • Journal of Power System Engineering
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    • v.18 no.6
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    • pp.207-214
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    • 2014
  • Mass and flow resistance in a square ribbed microchannel have been studied numerically using the Lattice Boltzmann Method. It has been build up on two dimensional nine velocity vectors model with single relaxation time method called the Lattice Bhatnagor-Gross-Krook model. To analyze the roughness effect on the flow resistance namely the friction factor and mass flow has been discussed at the slip flow regime, 0.01Kn0.10, where Kn is the Knudsen number. The wall roughness is considered by square microelements with a relative roughness height up to maximum 10% of channel height. The velocity profiles in terms of streamlines near the riblets are demonstrated to be responsible for the roughness effect. It is found that the roughness effect leads to increase the flow resistance with roughness height but it is decreased significantly with increasing the space between two roughness elements as well as the Knudsen number. In addition, the mass flow decreased linearly with increasing both roughness height and gap but significantly changed at the slip flow regime.

Modeling of chloride diffusion in concrete considering wedge-shaped single crack and steady-state condition

  • Yang, Keun-Hyeok;Cheon, Ju Hyun;Kwon, Seung-Jun
    • Computers and Concrete
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    • v.19 no.2
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    • pp.211-216
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    • 2017
  • Crack on concrete surface allows more rapid penetration of chlorides. Crack width and depth are dominant parameters for chloride behavior, however their effects on chloride penetration are difficult to quantify. In the present work, the previous anisotropic (1-D) model on chloride diffusion in concrete with single crack is improved considering crack shape and roughness. In the previous model, parallel-piped shape was adopted for crack shape in steady-state condition. The previous model with single crack is improved considering wedge shape of crack profile and roughness. For verifying the proposed model, concrete samples for nuclear power plant are prepared and various crack widths are induced 0.0 to 1.2 mm. The chloride diffusion coefficients in steady-state condition are evaluated and compared with simulation results. The proposed model which can handle crack shape and roughness factor is evaluated to decrease chloride diffusion and can provide more reasonable results due to reduced area of crack profile. The roughness effect on diffusion is evaluated to be 10-20% of reduction in chloride diffusion.

Process Effect on the RMS Roughness of CuInSe2 Thin Films Grown by MOMBE

  • Ko, Young-Don;Moon, Pyung;Yun, Il-Gu;Ham, Moon-Ho;Myoung, Jae-Min
    • Transactions on Electrical and Electronic Materials
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    • v.8 no.2
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    • pp.58-66
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    • 2007
  • In this paper, the process effect on the RMS roughness of the HfO2 thin films grown by metal organic molecular beam epitaxy was investigated. The measured RMS roughness is examined to characterize the surface morphology. In order to analyze the factor effects, the significant factors of both the main and the interaction effects were extracted through the effect analysis. In order to compare the regression model with the variable transformation, the effect of each factor and the model efficiency are calculated. The methodology can allow us to analyze the effects between the process parameters related to the process variability.

Change of Water Level in Vegetated Channels (식생된 수로에서의 수위변화 분석)

  • Kim, byeong-chan;Yun, seong-jun;Kim, min-jeong;Lee, jong-seok
    • Proceedings of the Korea Contents Association Conference
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    • 2008.05a
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    • pp.780-783
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    • 2008
  • This study developed a model that could calculate roughness using Manning's and Chezy coefficient for Yangjae-stream. The estimated roughness by model developed was used for roughness coefficient in the stream without water level-discharge data. Roughness coefficient was estimated using assumed and calculated water level about each discharge scale by unsteady flow analysis. As a result, error of water surface level by model was shown 1.29m, it was shown that the flow resistance tends to increase with the desity of vegetation.

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Determining Optimal Build Orientation in Fused Deposition Modeling for Minimizing Post Machining by Using Genetic Algorithm. (FDM(Fused Deposition Modeling) part의 후가공 최소화를 위한 최적성형방향 결정)

  • 안대건;김호찬;양화준;이일엽;장태식;정해도;이석희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.18-21
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    • 2003
  • Fused Deposition Modeling (FDM) parts are made by piling up thin layers that cause the stair stepping effect at the surface of FDM parts. This effect brings about poor surface roughness of the part and requires additional post machining such as manual finishing that is detrimental to the part geometry and time consuming. Determining optimal build orientation for FDM parts can be one solution to minimize the post machining. However, by using the CAD model, calculating the optimal build orientation is impractical due to heavy computing process. In order to calculate the optimal build orientation with high speed. the surface roughness model based on measured data and interpolation is newly developed in this research. Also. the genetic algorithm (GA) is applied for acquiring reliable solution. Finally, It is verified from the test that the presented approach is very efficient for reducing the additional post machining process fer FDM parts.

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Experimental Study of Ice Friction and Abrasion Test Methods for Polar Paint (극지용 도료의 빙마찰 및 빙마모 시험기법 연구)

  • Cho, Seong-Rak;Oh, Eun-Jin;Kim, Cheol-Hee;Lee, Jae-Man;Kim, Sung-Pyo
    • Journal of the Society of Naval Architects of Korea
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    • v.56 no.6
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    • pp.532-540
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    • 2019
  • This study describes a test method for evaluating the ice friction and abrasion performance of polar coatings. The evaluation methods of physical properties of general coatings for ocean-going vessels and polar coatings for ice-going vessels were investigated and their limitations were analyzed. We have also reviewed previous researches related to the development of polar paints and confirmed the necessity of developing test techniques. A flat steel plate was coated with several types of commercial coating, and cold model ice was used to cause ice friction and abrasion events between coated surface and ice. For evaluation of ice friction and abrasion performances, test procedures such as measurement of coating surface roughness, measurement of frictional force using model ice, implementation of ice abrasion and drying of coating surface were developed. The friction and abrasion characteristics of each coating are analyzed and summarized through the change of friction force and roughness data according to the progress of ice abrasion.

An Experimental and Analytical Study on the Impact Factors of Two-Span Continuous Plate Girder Bridge Due to Road Surface Roughness and Bump (노면조도와 단차를 고려한 2경간연속 판형교의 충격계수에 관한 실험 및 해석적 연구)

  • Park, Young Suk;Chung, Tae Ju
    • Journal of Korean Society of Steel Construction
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    • v.9 no.3 s.32
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    • pp.309-321
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    • 1997
  • The prediction of the dynamic response of a bridge resulting from passing vehicles across the span is a significant problem in bridge design. In this paper. the static and dynamic experiments are performed to understand the dynamic behavior of an actual two-span steel plate girder bridge. The road surface roughness of the roadway and bridge deck is directly measured by Intelligent Total Station. Numerical scheme to obtain the dynamic responses of the bridges in consideration of measuring road surface roughness and 3-D vehicle model is also presented. The bridge and vehicle are modeled as 3-D bridge and vehicle model, respectively. The main girder and concrete deck are modeled as beam and shell elements, respectively and rigid link is used for the structure between main girder and concrete deck. Bridge-vehicle interaction equations are derived and the impact factors of the responses for different vehicle speeds are calculated and compared with those predicted by several foreign specifications.

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Effects of coating material and cutting parameters on the surface roughness and cutting forces in dry turning of AISI 52100 steel

  • Keblouti, Ouahid;Boulanouar, Lakhdar;Azizi, Mohamed Walid;Yallese, Mohamed Athmane
    • Structural Engineering and Mechanics
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    • v.61 no.4
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    • pp.519-526
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    • 2017
  • In the present paper, the effects of cutting parameters and coating material on the performances of cutting tools in turning of AISI 52100 steel are discussed experimentally. A comparative study was carried out between uncoated and coated (with TiCN-TiN coating layer) cermet tools. The substrate composition and the geometry of the inserts compared were the same. A mathematical model was developed based on the Response Surface Methodology (RSM). ANOVA method was used to quantify the effect of cutting parameters on the machining surface quality and the cutting forces. The results show that feed rate has the most effect on surface quality. However, cutting depth has the significant effect on the cutting force components. The effect of coating layers on the surface quality was also studied. A lower surface roughness was observed when using PVD (TiCN-TiN) coated insert. A second order regression model was developed and a good accuracy was obtained with correlation coefficients in the range of 95% to 97%.