• Title/Summary/Keyword: Contact condition

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Prediction of Poor Contact by Analysis of Electrical Signal and Thermal Characteristics (전기적 신호와 열적특성 분석에 의한 접촉불량 예측)

  • Lee, Heung-Su;Kim, Doo-Hyun;Kim, Sung-Chul;Kim, Yoon-Bok
    • Journal of the Korean Society of Safety
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    • v.27 no.3
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    • pp.36-41
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    • 2012
  • Electrical Connections often cause fires due to poor contact. Occurrence rate of these fires tends to increase annually. The reason why poor contacts occur is often because it is the low mechanical pressure at the contact points. A typical connection method using mechanical pressure is a screw terminal type. This study reviewed these poor contact cases in the screw terminals. In order to get reproduction of such cases, two types of experiments were conducted. the first one was conducted under the normal contact condition, and the other one was conducted under the poor contact condition that screw terminal of breaker was loosen and did not meet the requirements of toque value. In both types of experiments, compulsory vibration was adopted as a variable to aggravate poor contacts. Each of various current values(4.5A, 9.0A, 13.5A) is input. In these experiments, relationships of a contact, electrical signal such as current and electric pulse by ZCT and thermal characteristics according to vibration effect are analyzed. The suggested data and results in this study provide the useful resources helping to investigate fires due to poor contact, and they develop the detector for poor contact and finally reduce the electrical fire occurrence rate.

A Study on the Contact Force and Temperature Distribution of Lip Seals (립실의 접촉력 및 온도분포 해석에 관한 연구)

  • 김청균;전인기;김종억
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.6
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    • pp.1559-1566
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    • 1994
  • Using the finite element method, the contact force, contact band width and temperature distribution of lip seals analyzed for the interference including some nonlinearities such as material nonlinearity, geometrical nonlinearity and nonlinear contact boundary condition. The calculated results showed that the contact stress concentrated on the contact zone between the garter spring and the rubber toward the flex side, the contact edge of lip seals. The high contact forces due to the increased interference separate the sealing gap between the lip edge and the rotating shaft. This may lead to leak the sealed oil.

Finite Element Analysis of Electrical Double Layers near Triple Contact Lines

  • Kang Kwan Hyoung;Kang In Seok;Lee Choung Mook
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.491-494
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    • 2002
  • To assess the electrostatic interaction of surfaces at the triple contact line, the electrostatic field is analyzed by using the finite element method. The Helmholtz free energy is used as a functional which should be minimized under an equilibrium condition. The numerical results are compared with the nonlinear analytical solution for a two-dimensional charged interface and linear solution for a wedge shaped geometry, which shows fairly good agreement. The method is applied to the analysis of electrostatic influence on the contact angle on a charged substrate. The excess free energy found to increase drastically as the contact angle approaches to zero. This excess free energy Plays an opposite role to the Primary electrocapillary effect, as the contact angle gets smaller. This enables an alternative explanation for the contact-angle saturation phenomenon occurring in electrical control of surface tension and contact angle.

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Analysis of Dynamic Characteristics of Contact Slider Over Practical Disk Surface (실제 디스크 표면 데이터에 대한 접촉 슬라이더의 동적 안정성 해석)

  • 박경수;전정일;박영필;박노철
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.160-165
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    • 2002
  • The flying height of contact slider is determined by vertical and pitching motions. This paper performed the computer simulation for flying height change of contact slider. It is changed by many parameters, contact stiffness. contact damping, all bearing stiffness ratio and so on. So computer simulation analysis is performed for knowing for what change of these parameters influences in flying height of contact slider. The practical recording zone surface is gotten by using SPM. In recording zone, flying height is simulated for each parameter. the settling time which the flying height of contact slider is lower than 10nm is analyzed over practical disk surface for changing each parameter. Through these results, the contact slider can be analyzed for more accuracy dynamic characteristics.

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Conditions for Assuming Hertzian Stress for the Contact between a Circular Pin and Hole (원형 핀과 구멍의 접촉에서 헤르츠 응력장 가정을 위한 조건)

  • Kim, Hyung-Kyu
    • Tribology and Lubricants
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    • v.31 no.5
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    • pp.189-194
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    • 2015
  • This paper focuses on the conformal contact problem. A typical example of conformal contact is the contact between a pin and hole. In particular, this paper focuses on the condition for assuming a contact stress field to be a Hertzian pressure profile by using well-known classical solutions associated with Hertzian contact. Persson first developed the conformal contact analysis method around half a century ago, but there have been no significant improvements since then. The present research also adopted this method, but developed new solutions from the viewpoint of application to structural design. The analysis began with a comparison between Persson°Øs conformal contact stress and the Hertzian stress fields. The next step was to check the differences in the normalized stress values of both. This study used the tolerance for the difference in the peak stresses of Persson°Øs solution and the Hertz solution to validate the Hertzian assumption. This gave the range for the difference in radii of the pin and hole when the contact force and mechanical properties of the material are specified. The results showed that, at a tolerance of 5%, the Hertzian assumption is valid if half of the contact angle is less than 35°ý. In addition, the Hertzian assumption holds even for a relatively long contact length, in contrast to the general incomplete contact problem. This paper discusses these results along with other aspects of the application to the design.

SCALAR CURVATURE OF CONTACT CR-SUBMANIFOLDS IN AN ODD-DIMENSIONAL UNIT SPHERE

  • Kim, Hyang-Sook;Pak, Jin-Suk
    • Bulletin of the Korean Mathematical Society
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    • v.47 no.3
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    • pp.541-549
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    • 2010
  • In this paper we derive an integral formula on an (n + 1)-dimensional, compact, minimal contact CR-submanifold M of (n - 1) contact CR-dimension immersed in a unit (2m+1)-sphere $S^{2m+1}$. Using this integral formula, we give a sufficient condition concerning with the scalar curvature of M in order that such a submanifold M is to be a generalized Clifford torus.

On N(κ)-Contact Metric Manifolds Satisfying Certain Curvature Conditions

  • De, Avik;Jun, Jae-Bok
    • Kyungpook Mathematical Journal
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    • v.51 no.4
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    • pp.457-468
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    • 2011
  • We consider pseudo-symmetric and Ricci generalized pseudo-symmetric N(${\kappa}$) contact metric manifolds. We also consider N(${\kappa}$)-contact metric manifolds satisfying the condition $S{\cdot}R$ = 0 where R and S denote the curvature tensor and the Ricci tensor respectively. Finally we give some examples.

Influence of Stress Shape Function on Analysis of Contact Problem Using Hybrid Photoelasticity (광탄성 실험 하이브리드 법에 의한 접촉응력 해석시 응력형상함수의 영향)

  • Shin, Dong-Chul;Hawong, Jai-Sug
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.3
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    • pp.345-352
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    • 2013
  • In this research, a study on stress shape functions was conducted to analyze the contact stress problem by using a hybrid photoelasticity. Because the contact stress problem is generally solved as a half-plane problem, the relationship between two analytical stress functions, which are compositions of the Airy stress function, was similar to one of the crack problem. However, this relationship in itself could not be used to solve the contact stress problem (especially one with singular points). Therefore, to analyze the contact stress problem more correctly, stress shape functions based on the condition of two contact end points had to be considered in the form of these two analytical stress functions. The four types of stress shape functions were related to the stress singularities at the two contact end points. Among them, the primary two types used for the analysis of an O-ring were selected, and their validities were verified in this work.

Finite Element Analysis of the Contact Stress Characteristics in Scraper Seals (스크레이퍼 실의 접촉응력 특성에 관한 유한요소해석)

  • Kim, Chung-Kyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.6 s.165
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    • pp.895-902
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    • 1999
  • This paper deals with a numerical study of the tribological contact stress distributions of elastomeric lip seals for oscillating shafts when the sealing interference and band width between the lip ease or contact seals and the shaft are present. Using the finite element method the contact stress and band width of scraper seals are analyzed for the sealing interference including some nonlinearities such as geometrical nonlinearity, material nonlinearity and nonlinear contact boundary condition. The FEM results showed that the contact stress concentrated on the contacting lip zone between the contacting edge of lip and the shaft for the increased interference. In double lip scraper seals, ole maximum contact stress of the dust lip, which is used to exclude foreign contaminants is six times higher than that of the primary sealing lip, which is used to contain lubricants.

Study on the Fluid Film Thickness and Pressure of Elliptical Elastohydrodynamic Lubrication with Spin Effect for the Power Transmitting Contact in the Continuously Variable Transmission (무단 변속기의 동력전달 접촉에서 회전운동을 고려한 타원형상의 점접촉 탄성유체윤활연구)

  • Jang, Si-Youl
    • Tribology and Lubricants
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    • v.21 no.6
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    • pp.272-277
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    • 2005
  • Continuously variable transmission (CVT) of toroidal type has a elliptical shape of contact zone under the elastohydrodynamic lubrication (EHL) condition, where the power is transmitted only by shearing the lubricant. Due to the small contact area of elliptical shape, the traction of the shear behaviors of lubricant over the contact zone is under extremely high contact pressure over 1.0GPa. During the power transmission by shearing the fluid, many kinds of mechanical movements occur such as squeezing, sliding, rolling and spin. Among the movements, the spin effect that is the most undesirable contact behavior in transmitting the power frequently makes significant abnormal wear damage. In this work, the analysis of elliptical contact of EHL with spin effect is performed, which will give very useful information to understand the traction behaviors in toroidal type of CVT system.