• Title/Summary/Keyword: Rough surface

Search Result 939, Processing Time 0.031 seconds

Contact Fatigue Life Prediction of Automotive Wheel Bearing (차량용 휠베어링의 접촉 피로수명 예측에 관한 연구)

  • Lee, Sang-Don;Moon, Kil-Hwan;Cho, Yong-Joo
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.16 no.3
    • /
    • pp.137-143
    • /
    • 2008
  • For most bearings, it is a common requirement to have long durability. Especially wheel bearing fatigue life is the most important in automotive quality. The contact fatigue life analysis of automotive wheel bearing considering real raceway rough surface is presented in this paper. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions; the subsurface stress field is obtained using rectangular patch solutions. Mesoscopic multiaxial fatigue criterion which can yield satisfactory results for non-proportional loading is then applied to predict fatigue damage. Suitable counting method and damage rule were used to calculate the fatigue life of random loading caused by rough surface. The life analysis considering real rough surface of wheel bearing raceway is in good agreement with the experimental results.

The Contact Fatigue Life Analysis of Rough Surfaces (거친 표면의 접촉피로 수명예측)

  • Chu Hyo-Jun;Lee San-Don;Cho Yong-Joo
    • Tribology and Lubricants
    • /
    • v.21 no.3
    • /
    • pp.136-141
    • /
    • 2005
  • Analytical model to calculate the contact fatigue life of rough surface is presented in this paper. The effect of surface roughness can be calculated by this model. Computational method and the theoretical basis are also discussed. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions; the subsurface stress field is obtained using rectangular patch solutions. Mesoscopic multiaxial fatigue criterion which can yield satisfactory results for non-proportional loading is then applied to predict fatigue damage. Suitable counting method and damage rule were used to calculate the fatigue life of random loading caused by rough surface. As a result of analysis the relationship between the life and the roughness as well as the most probable depth of the crack initiation is calculated.

A Study on the Centrifugal Barrel Machining of Round Face (원형단면의 정밀 원심 배럴가공에 관한 연구)

  • 고준빈;김우강;원종호
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.21 no.4
    • /
    • pp.179-185
    • /
    • 2004
  • Surface finish technology is highly demanded in the wide field of industry applications from ultra-precision parts to rough casting parts. Therefore, many kinds of surface finish technologies have been developed for each purpose. Because surface of a car's wheel cast is very rough it becomes the reason of the corrosion. This surface is coated to complement such problem but because surface is rough, the result of coating is not good and the coated metal peels off well. Therefore before the wheel is coated, it is necessary to grind the surface. In this study, we devised the plant to apply a barrel machining to improve the surface roughness and enhance the productivity. Also we could obtain the optimum barrel machining conditions for the proper surface roughness.

Numerical Analysis of Back Scattering from a Target over a Random Rough Surface Using DRTM

  • Yoon, Kwang-Yeol
    • Journal of electromagnetic engineering and science
    • /
    • v.10 no.2
    • /
    • pp.61-66
    • /
    • 2010
  • This paper is concerned with an analysis of the back scattering of electromagnetic waves from a target moving along random rough surfaces such as the desert, and sea. First, the discrete ray tracing method(DRTM) is introduced, and then, this method is applied to the back scattering problem in order to investigate the effect of the back scattering from random rough surfaces on the electric field intensities. Finally, numerical examples of various height deviations of the Gaussian type of rough surfaces are shown. It is numerically demonstrated that the back scattering is dominated by the diffractions related to the reflections from the random rough surfaces.

Transition of Turbulent Boundary Layer with a Step Change from Smooth to Rough Surface (표면 형상 변화에 따른 난류경계층 유동장 분석)

  • Lee, Jae Hwa
    • Journal of the Korean Society of Visualization
    • /
    • v.12 no.3
    • /
    • pp.15-20
    • /
    • 2014
  • Direct numerical simulation (DNS) dataset of a turbulent boundary layer (TBL) with a step change from smooth to rough surface is analyzed to examine spatially developing flow characteristics. The roughness elements are periodically arranged two-dimensional (2-D) spanwise rods with a streamwise pitch of ${\lambda}=8k$ ($=12{\theta}_{in}$), and the roughness height is $k=15{\theta}_{in}$, where ${\theta}_{in}$ is the inlet momentum thickness. The step change is introduced $80{\theta}_{in}$ downstream from the inlet. For the first time, full images from the DNS data with the step change from the smooth to rough walls is present to get some idea of the geometry of turbulent coherent structures over rough wall, especially focusing on their existence and partial dynamics over the rough wall. The results show predominance of hairpin vortices over the rough wall and their spanwise scale growth mechanism by merging.

A study for improve MCPs product surface about injection process (MCPs 사출 제품의 Gate 부근에 발생하는 Gas Flow Mark 개선을 위한 사출성형 공정 연구)

  • Hyun C.H.;Cha S.W.;Lee D.W.;Park Y.W.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2005.06a
    • /
    • pp.1710-1714
    • /
    • 2005
  • Micro Cellular Plastics create a sensation at polymer industrial for lowering product cost & overcoming a lowering of mechanical intensity. This research is surface quality research of MCPs product Through surface rough measurement. This experiment is carried out according to injection speed control with the surface rough & Product surface quality are searched

  • PDF

Effect of presurfacing on drying rate and drying defect of Quercus grosseserrata BI. (전평삭처리(前平削處理)가 물참나무의 건조속도(乾燥速度)와 건조결함(乾燥缺陷)에 미치는 영향(影響))

  • Han, Gyu-Seong;Jung, Hee-Suk
    • Journal of the Korean Wood Science and Technology
    • /
    • v.14 no.4
    • /
    • pp.29-39
    • /
    • 1986
  • To investigate the effect of presurfacing, both 25mm rough and pre surfaced oak boards (Quercus grosseserrata BI.) were dried in the same dry kiln condition. Drying curves, drying strains and drying defects of rough and presurfaced boards were compared. The results obatained are as follows. 1. Average drying rate of rough and presurfaced boards from green to 10% M.C. was 0.276%/hr. and 0.284%/hr., respectively. 2. At the early stage of drying, in case of rough boards, maximum tensile strain of outer slices was $-24.2{\times}10^{-4}$mm/mm and maximum compressive strain of innermost slices was $13.0{\times}10^{-4}$mm/mm, and in case of pre surfaced boards, maximum tensile strain of outer slices was $-14.5{\times}10^{-4}$mm/mm and maximum compressive strain of innermost slices was $28.1{\times}10^{-4}$mm/mm. And in both cases, stress reversal occurred at about 40% M.C.. 3. Maximum surface checking appeared at about 40% M.C.. Of the 10 rough boards. 6 hoards contained surface checks, but presurfaced boards did not contained surface checks after drying. And the results of end checking were similar to those of surface checking. But, honeycomb was not found in both cases. 4. Board shrinkage. warp and casehardening of presurfaced boards were similar to those of rough boards. But, collapse of prsurfaced boards was less than that of rough boards.

  • PDF

Rough surface characterization using off-axis digital holographic microscopy compensated with self-hologram rotation

  • Ibrahim, Dahi Ghareab Abdelsalam
    • Current Applied Physics
    • /
    • v.18 no.11
    • /
    • pp.1261-1267
    • /
    • 2018
  • In this paper, an off-axis digital holographic microscopy compensated with self-hologram rotation is presented. The process is implemented via subtracting the unwrapped phase maps of the off-axis parabolic hologram and its rotation $180^{\circ}$ to eliminate the tilt induced by the angle between the spherical object wave O and the plane reference wave R. Merit of the proposed method is that it can be done without prior knowledge of physical parameters and hence can reconstruct a parabolic hologram of $1024{\times}768$ pixels within tens of milliseconds since it doesn't require a digital reference wave. The method is applied to characterize rough gold bumps and the obtained results were compared with those extracted from the conventional reconstruction method. The comparison showed that the proposed method can characterize rough surfaces with excellent contrast and in realtime. Merit of the proposed method is that it can be used for monitoring smaller biological cells and micro-fluidic devices.

Discrete Ray Tracing Techniques for Wave Propagation Characteristic of Random Rough Surfaces (불규칙 조면의 전파 특성 해석을 위한 이산 광선 추적법)

  • Yoon, Kwang-Yeol
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.5 no.3
    • /
    • pp.233-238
    • /
    • 2010
  • In this paper, we have proposed discrete ray tracing method (DRTM) for numerical analysis of characteristics of electromagnetic propagation along 2D random rough surfaces. The point of the present method is to discretize not only rough surface but also ray tracing. The former helps saving computer memories and the latter does simplifying ray searching algorithm resulting in saving computation time. Numerical calculations are carried out for 2D random rough surfaces, and electric field distributions are shown to check the effectiveness of the proposed DRTM.

Precision Profile Measurement on Roughly Processed Surfaces (거친 가공표면 형상의 고정밀 측정법 개발)

  • Kim, Byoung-Chang;Lee, Se-Han
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.7 no.1
    • /
    • pp.47-52
    • /
    • 2008
  • We present a 3-D profiler specially devised for the profile measurement of rough surfaces that are difficult to be measured with conventional non-contact interferometer. The profiler comprises multiple two-point-diffraction sources made of single-mode optical fibers. Test measurement proves that the proposed profiler is well suited for the warpage inspection of microelectronics components with rough surface, such as unpolished backsides of silicon wafers and plastic molds of integrated-circuit chip package.

  • PDF