• Title/Summary/Keyword: 관통길이 비

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Evaluation of Crack Growth Estimation Parameters of Thick-Walled Cylinder with Non-Idealized Circumferential Through-Wall Cracks (비 이상화된 원주방향 관통균열이 존재하는 두꺼운 배관의 균열 성장 매개변수 계산)

  • Han, Tae-Song;Huh, Nam-Su;Park, Chi-Yong
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.2
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    • pp.138-146
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    • 2013
  • The present paper provides the elastic stress intensity factors(SIFs) of thick-walled cylinder with non-idealized circumferential through-wall cracks. For estimating these elastic SIFs, the systematic three-dimensional(3D) elastic finite element(FE) analyses were performed. In order to consider practical shape of thick-walled cylinder and non-idealized circumferential through-wall crack, the values of thickness of cylinder, reference crack length and crack length ratio were systematically varied. As for loading conditions, axial tension, global bending and internal pressure were considered. In particular, in order to calculate the SIFs of thick-walled cylinder with non-idealized circumferential through-wall crack from those of thick-walled cylinder with idealized circumferential through-wall crack, the correction factor representing the effect of non-idealized crack on the SIFs were proposed in this paper. The present results can be applied to accurately evaluate the rupture probabilities of nuclear piping considering actual crack growth behaviors.

The elastic bucking strength of axially compressed tubular member with through-gusset connection (관통한 가셋트판이 부착된 압축 강관 부재의 탄성좌굴내력)

  • Kim, Woo-Bum;Lim, Ji-Youn
    • Journal of Korean Society of Steel Construction
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    • v.13 no.2
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    • pp.133-141
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    • 2001
  • A tubular member holding an axially through-gusset connection is often used to transmit axial compression in a steel truss structures. The elastic buckling loads of the member is affected by the stiffness ratio($\beta$) and the length ratio(G) because of two elements with different properties. In current code, however, the strength is evaluated with an effective length factor k=0.9 without considering the above effect. Therefore this study analyzed a theoretical mechanism based on the elasticity theory and performed a finite element analysis to investigate the influence parameters on the elastic buckling strength of axially loaded member.

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A Study on Puncture Properties of Short-fiber Reinforced Rubber (단섬유 강화고무의 관통 특성 연구)

  • Ryu, Sang-Ryeoul;Lee, Dong-Joo
    • Composites Research
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    • v.19 no.6
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    • pp.16-22
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    • 2006
  • The puncture properties under various conditions were investigated for the optimum conditions to yield the best properties. Fiber aspect ratio(AR: length of fiber/diameter of fiber), interphase condition and fiber content were considered as variables which impact the puncture force and friction force. The puncture force of short-fiber reinforced rubber increases up to 3.4 times compared to the virgin material. The better interphase condition shows the higher puncture force at given fiber AR and fiber content. The friction force of the matrix and reinforced rubber with a fiber AR below 155 does not exist. The friction force of the reinforced rubber with the good interphase condition and high fiber AR is higher than puncture force of matrix. Overall, it was found that the interphase condition, fiber AR and fiber content have an important effect on the puncture properties.

Estimates of Elastic Fracture Mechanics Parameters for Thick-Walled Pipes with Slanted Axial Through-Wall Cracks (두꺼운 배관에 존재하는 축방향 경사관통균열의 탄성파괴역학 매개변수 계산)

  • Han, Tae-Song;Huh, Nam-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.12
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    • pp.1521-1528
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    • 2012
  • The present paper provides the elastic stress intensity factors (SIFs) and the crack opening displacements (CODs) of a thick-walled pipe with a slanted axial through-wall crack. For estimating these elastic fracture mechanics parameters, systematic three-dimensional elastic finite element (FE) analyses were performed by considering geometric variables, i.e., thickness of pipe, reference crack length, and crack length ratio, affecting the SIFs and CODs. As for loading condition, the internal pressure was considered. Based on the FE results, the SIFs and CODs of slanted axial through-wall cracks in a thickwalled pipe along the crack front and the wall thickness were calculated. In particular, to calculate the SIFs of a thick-walled pipe with a slanted axial through-wall crack from those of a thick-walled pipe with an idealized axial through-wall crack, a slant correction factor representing the effect of the slant crack on the SIFs was proposed.

Effects of Specimen Size and Testing Velocity on Puncture Properties of Short-fiber Reinforced Chloroprene Rubber (시편 크기 및 시험속도가 단섬유 강화 클로로프렌 고무의 관통 특성에 미치는 영향)

  • Ryu, Sang-Ryeoul;Lee, Dong-Joo
    • Composites Research
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    • v.20 no.6
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    • pp.28-33
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    • 2007
  • The puncture properties of short-fiber reinforced rubber were investigated as functions of fiber aspect ratio(AR: length of fiber/diameter of fiber), fiber content, specimen size and testing velocity. The puncture stresses of the matrix and short-fiber reinforced rubber decreased with specimen size, and increased with testing velocity at same specimen size. As the fiber AR increased the puncture stress at given fiber content also increased. The problem of the specimen shape was investigated by the comparison of the tensile strength with puncture stress. The forces acting in the membrane wall of the matrix and the short-fiber reinforced rubber showed a similar data regardless of specimen size. And those increased with testing velocity at same specimen size. As the fiber AR increased the force acting in the wall at given fiber content also increased. Overall, it was found that the specimen size, testing velocity had an important effects on the puncture properties.

Finite Element Analysis for the Penetration Phenomena of Shaped Charge Jets using Hydrodynamic Theory (Hydrodynamic 이론을 이용한 성형작약탄두 제트의 관통 현상에 관한 유한요소 해석)

  • Kang, Youngku
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.2
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    • pp.133-140
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    • 2019
  • In this paper, the penetration process of Shaped charge jet(SCJ) was simulated through finite element analysis to obtain physical quantities such as jet incidence velocity, penetration rate, and penetration increment. As a result of applying these physical quantities to the hydrodynamic theory, it was confirmed that the penetration efficiency of the jet with a high incident velocity is higher than that of the following slow jet. This efficiency decreased sharply when the jet was slower than the hydrodynamic limit(HL). On the other hand, the comparison of penetration increment and jet consumption over time showed that the length extension effect should be considered for SCJ's theoretical penetration analysis.

A Study on the Buckling Strength and Effective Length of Tubular Member with Gusset Plate Considering End Restraints (단부구속효과를 고려한 관통 가셋트 부착 강관부재의 좌굴내력 및 유효세장비 산정에 관한 연구)

  • Kim, Woo Bum
    • Journal of Korean Society of Steel Construction
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    • v.15 no.2
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    • pp.159-165
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    • 2003
  • A tubular member with through-gusset plate is often used to transmit axial compression in an electric transmission towers. In current code, the strength of tubular member is evaluated with an effective length factor k=0.9 without considering the deformation of boundary element. A buckling strength of member with end gusset plate is affected by stiffness ratio($\beta$) and the length ratio(G) between main tubular member and end gusset plate. In this study theoretical mechanism based on the elastic buckling behavior was investigated, and finite element analysis was performed to propose a formula for the buckling strength and effective length factor of tubular member in elsatic and inelastic ranges.

Study of Hypervelocity Penetration Characteristics of Segmented Tungsten Penetrator (분절형 텅스텐 관통자의 초고속 관통특성에 관한 연구)

  • Jo, Jong Hyun;Lee, Young Shin;Kim, Jae Hoon;Bae, Yong Woon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.8
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    • pp.953-960
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    • 2013
  • This study aimed to investigate the penetration characteristics of a segmented penetrator with normal and inclined angles. The length to diameter ratio (L/D) of the segmented penetrator was varied as 1.0, 0.5, and 0.25. Moreover, impact velocities of 1.5, 2.0, and 2.5 km/s and inclination angles of $15^{\circ}$, $30^{\circ}$, and $45^{\circ}$ were successively applied. The AUTODYN-3D code was used to simulate the penetration performance of the segmented penetrator. The results show that the penetration performance of the segmented penetrator with steel plates was obviously higher than that of the corresponding continuous penetrator with steel plates. The outstanding penetration performance of the segmented penetrator can be observed when the impact velocity was 2.0 km/s and L/D = 1. In this case, the penetration performance of the segmented penetrator was 7% higher than that of the corresponding continuous penetrator. This trend was attributable to the interaction between the reactive plate and the projectile. The extent of the interaction relies on the relative velocities of the plate and projectiles, inclination angle, and number of segmented penetrators. It was proven that the penetration performance of the segmented penetrator can be improved by increasing the impact velocity, number of segmented penetrators between segments, and penetrator length.

Study on Penetration Characteristics of Tungsten Cylindrical Penetrator (텅스텐 원형 관통자의 관통특성에 관한 연구)

  • Jo, Jong Hyun;Lee, Young Shin;Kim, Jae Hoon;Bae, Yong Woon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.9
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    • pp.1083-1091
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    • 2013
  • The design of missile require extremely small warheads that must be highly efficient and lethal. The penetration characteristics of each penetrator and the total number of penetrators on the warhead are obvious key factors that influence warhead lethality. The design of the penetrator shape and size are directly related to the space and weight of the warhead. The design of the penetrator L/D was directly related to the space and weight of the warhead. L and D are the length and the diameter of the projectile, respectively. The AUTODYN-3D code was used to study the effect of penetrator penetration. The objective of numerical analysis was to determine the penetration characteristics of penetrator produced by hypervelocity impacts under different initial conditions such as initial velocity, obliquity angle and L/D of penetrator. The residual velocity and residual mass were decreased with increasing initial impact velocity under $L/D{\leq}4$.

Fatigue Behavior of Before-and-After Penetration of Aluminium Plate with Long Surface Crack (긴 균열을 갖는 알루미늄판재의 관통전후 피로거동)

  • Nam Ki-Woo;Lee Jong-Rark;Ahn Seok-Hwan
    • Journal of the Korean Institute of Gas
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    • v.3 no.1
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    • pp.1-7
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    • 1999
  • Fatigue behavior of before-and-after penetration was examined experimentally using surface pre-cracked specimens of aluminium alloy 5083-0. The fatigue crack shape before penetration is almost semicircular, and the measured aspect ratio is larger than the value obtained by calculation using K values proposed by Newman-Raju. It is found that the crack growth behavior on the back side after penetration is unique and can be divided into three stages. By using a crack propagation rule in case of long surface crack, the change in crack shape after penetration can be evaluated quantitatively.

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