• Title/Summary/Keyword: Surface Intensity

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Stress Intensity factor Analysis for Three-Dimensional Cracks in Inhomogeneous Materials (비균질재료의 3차원 균열에 대한 응력확대계수 해석)

  • 김준수;이준성
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.4
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    • pp.197-203
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    • 2003
  • Accurate stress intensity factor analyses and crack growth rate of surface -cracked components in inhomogeneous materials are needed fur reliable prediction of their fatigue life and fracture strengths. This paper describes an automated stress intensity factor analysis of three-dimensional (3D) cracks in inhomogeneous materials. 3D finite element method (FEM) was used to obtain the stress intensity factor fur subsurface cracks and surface cracks existing in inhomogeneous materials. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in a plate subjected to uniform tension is calculated, and compared with Raju-Newman's solutions. Then the system is applied to analyze cladding effect of subsurface cracks in inhomogeneous materials. The results were compared with those surface cracks in homogeneous materials. It is clearly demonstrated from these analyses that the stress intensity factors for subsurface cracks are less than those of surface cracks. Also, this system is applied to analyze cladding effect of surface cracks in inhomogeneous materials.

Stress Intensity Factor Analysis for Surface Crack in Inhomogeneous Materials (비균질재료의 표면균열에 대한 응력확대계수 해석)

  • 김준수;이준성
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.816-819
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    • 2002
  • Accurate stress intensity factor analyses and crack growth rate of surface-cracked components in inhomogeneous materials are needed for reliable prediction of their fatigue lift and fracture strengths. This paper describes an automated system for analyzing the stress intensity factors of three-dimensional (3D) cracks in inhomogeneous materials. 3D finite element method (FEM) was used to obtain the stress intensity factor for subsurface cracks and surface cracks existing in inhomogeneous materials. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in a plate subjected to uniform tension is calculated, and compared with Raju-Newman's solutions. Then the system is applied to analyze cladding effect of subsurface cracks in inhomogeneous materials. The results were compared with those surface cracks in homogeneous materials. It is clearly demonstrated from these analyses that the stress intensity factors for subsurface cracks are less than those of surface cracks.

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Determination of Stress Intensity Factors for Embedded Elliptical Crack in Turbine Rotor (터빈축차내에 내재된 타원균열의 응력세기계수 결정)

  • 이강용;김종성;하정수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.5
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    • pp.1229-1242
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    • 1995
  • The thermal shock stress intensity factors of semi-elliptical surface crack in finite plate and the stress intensity fractors of embedded elliptical crack in turbine rotor is determined by means of Vainshtok weight function method. In case of semi-elliptical surface crack, the solution is compared with previous solution. The stress intensity factor for embedded elliptical crack in turbine rotor loaded by centrifugal and thermal loading is also determined. In this case, the value of stress intensity factor is larger at crack contour near internal radius surface and is almost constant at the crack contour farther from internal radius surface.

Effect of the yield criterion on the strain rate and plastic work rate intensity factors in axisymmetric flow

  • Lyamina, Elena A.;Nguyen, Thanh
    • Structural Engineering and Mechanics
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    • v.58 no.4
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    • pp.719-729
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    • 2016
  • The main objective of the present paper is to study the effect of the yield criterion on the magnitude of the strain rate and plastic work rate intensity factors in axisymmetric flow of isotropic incompressible rigid perfectly plastic material by means of a problem permitting a closed-form solution. The boundary value problem consisting of the axisymmetric deformation of a plastic tube is solved. The outer surface of the tube contracts. The radius of the inner surface does not change. The material of the tube obeys quite a general yield criterion and its associated flow rule. The maximum friction law is assumed at the inner surface of the tube. Therefore, the velocity field is singular near this surface. In particular, the strain rate and plastic work rate intensity factors are derived from the solution. It is shown that the strain rate intensity factor does not depend on the yield criterion but the plastic work rate intensity factor does.

A study on the Measurement of Field Transmission Loss through Doors in Buildings Using the Surface Intensity Method. (Surface Intensity 법에 의한 건물내 출입문의 차음성능 현장측정에 관한 연구)

  • 손장열;오재응;김흥식
    • The Journal of the Acoustical Society of Korea
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    • v.4 no.2
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    • pp.3-12
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    • 1985
  • The surface intensity method is a relatively new tool which can identify the noise source or path and measure the radiation power. One microphone and one accelerometer are used in this new technique. In this study, this new technique has been used to measure the field transmission loss trough doors. The results of the experiment indicate that the surface intensity method produces reliable data and can be applied to the transmission loss measurement.

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A study on the Measurement of Field Transmission Loss through Doors in Buildings Using the Surface Intensity Method. (Surface Intensity 법에 의한 건물내 출입문의 차음성능 현장측정에 관한 연구)

  • Son, Jang Yeol;O, Jae Eung;Kim, Heung Sik
    • The Journal of the Acoustical Society of Korea
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    • v.4 no.2
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    • pp.3.1-3.1
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    • 1985
  • The surface intensity method is a relatively new tool which can identify the noise source or path and measure the radiation power. One microphone and one accelerometer are used in this new technique. In this study, this new technique has been used to measure the field transmission loss trough doors. The results of the experiment indicate that the surface intensity method produces reliable data and can be applied to the transmission loss measurement.

Contrast Enhancement Technique by Intensity Surface Stretching (명도 표면 스트레칭에 의한 화질 개선 기법)

  • Kim, Do-Hyeon;Jung, Ho-Young;Cha, Eui-Young
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.12
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    • pp.2398-2405
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    • 2007
  • This paper proposes a contrast enhancement technique which stretches the intensity surfaces of image to improve the quality of the digital photos. The proposed method enhances the contrast of image by stretching the intensity surface of the original image to the maximum range of the output image in proportion to the distances between the original intensity surface and upper, lower intensity surface, respectively. The upper and lower intensity surfaces are generated from the original intensity surface by gaussian smoothing. In the experiments, digital color images in a variety of illumination conditions were used and the proposed method was compared with other several existed image enhancement algorithms, which are histogram stretching, surface stretching, histogram equalization, gamma correction and retinex. It was proved that the experimental results were more natural visually without deterioration of gradation.

Estimation of Surface Profile Using Reflected Laser Beam Pattern (레이저 빔 반사 패턴을 이용한 표면 프로파일 추정)

  • 서영호;김화영;안중환
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.263-266
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    • 2002
  • An optical method for surface roughness estimation based on statistical analysis of the light intensity of a scattered laser beam pattern. The method is very simple but has a disadvantage that no more information than the averaged roughness is estimated. In this study a new try was conducted to derive more advanced surface information from the details of the light intensity distribution. Some periodic ripples among the light intensity distribution being assumed to relate with scratch left on the machined surface, a corresponding surface profile is estimated from the ripples using FFT and IFFT algorithm. IFFT technique is used to extract some dominant signal components among the intensity distribution. Compared to the measured profiles by a stylus type surf-tester, the profiles obtained through the proposed method are probably acceptable in a sense of the profile shape. Calibration of the amplitude needs more works in the future.

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Evaluation of Stress Intensity Factor after Penetration of Plate with Long Surface Crack (긴 표면균열재의 관통후 응력확대계수 평가)

  • Nam Kiwoo;Lee Jongrark
    • Journal of the Korean Institute of Gas
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    • v.4 no.1 s.9
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    • pp.33-39
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    • 2000
  • Stress intensity factor after penetration was discussed experimentally using long surface pre-cracked specimens of aluminum alloy 5083. The propagation behavior evaluation of long surface crack by equation proposed at penetration of short surface crack could be need modification to evaluate precisely because the error was high as aspect ratio is little. The modification of stress intensity factor with consideration of aspect ratio at penetration of long surface crack can be analyzed the behavior of crack penetration quantitatively.

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Decreasing Technique of the Electric-field Intensity on Transmission Conductor Surface using the Hybrid Conductor Bundle (2종소도체 배열방식을 적용한 송전도체 표면전계강도 저감기법)

  • Lee, Dong-Il;Sin, Gu-Yong;Kim, Jeong-Bu
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.7
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    • pp.542-549
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    • 1999
  • Corona discharges form at the surface of a transmission line conductor when the electric-field intensity on the conductor surface exceeds the breakdown strength of air. In order to decrease the electric-field intensity on the conductor surface, a new 6 conductor bundle has been studied. This bundle, hybrid conductor bundle, consists of using a larger subconductor at the bottom two conductor positions in the 6-conductor bundles of each phase of the line. The electric field on these two larger subconductors is reduced which in turn reduces the corona noise. It is shown that this is a better solution for decreasing the electric-field intensity than ether the conventional bundle or the asymmetric bundle proposed by EPRI.

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