• Title, Summary, Keyword: 한계하중

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Mis-Match Limit Load Analyses and Fracture Mechanics Assessment for Welded Pipe with Circumferential Crack at the Center of Weldment (용접부 중앙에 원주방향균열이 있는 배관에 대한 강도불일치 한계하중 해석 및 파괴역학 평가)

  • Song, Tae-Kwang;Jeon, Jun-Young;Shim, Kwang-Bo;Kim, Yun-Jae;Kim, Jong-Sung;Jin, Tae-Eun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.1
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    • pp.19-26
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    • 2010
  • In this paper, limit load analyses and fracture mechanics analyses were conducted via finite element analyses for the welded pipe with circumferential crack at the center of the weldment. Systematic changes for strength mismatch ratio, width of weldment, crack shape and thickness ratio of the pipe were considered to provide strength mismatch limit load. And J-integral calculations based on reference stress method were conducted for two materials, stainless steel and ferritic steel. Reference stress defined by provided strength mis-match limit load gives much more accurate J-integral.

Lower Bound Net-Section Limit Loads for Circumferential Part-Through Surface Cracked Pipes under Combined Pressure and Bending (내압과 굽힘의 복합하중을 받는 원주방향 표면균열 배관에 대한 하한계 실단면 한계하중)

  • Oh, Chang-Kyun;Kim, Jong-Sung;Jin, Te-Eun;Kim, Yun-Jae
    • Proceedings of the KSME Conference
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    • pp.1772-1777
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    • 2007
  • This paper provides plastic limit loads of pipes with constant-depth, circumferential part-through surface cracks under combined pressure and bending. A key issue is to postulate discontinuous hoop stress distributions in the net-section. Validity of the proposed limit load solutions is checked against the results from three-dimensional (3-D) finite element (FE) limit analyses using elastic-perfectly plastic material behavior.

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Limit Loads for Pipe Bends under Combined Pressure and in-Plane Bending Based on Finite Element Limit Analysis (압력과 모멘트의 복합하중을 받는 곡관에 대한 유한요소 한계하중 해석)

  • Oh Chang-Sik;Kim Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.5
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    • pp.505-511
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    • 2006
  • In the present paper, approximate plastic limit load solutions fur pipe bends under combined internal pressure and bending are obtained from detailed three-dimensional (3-D) FE limit analyses based on elastic-perfectly plastic materials with the small geometry change option. The present FE results show that existing limit load solutions for pipe bends are lower bounds but can be very different from the present FE results in some cases, particularly for bending. Accordingly closed-form approximations are proposed for pipe bends under combined pressure and in-plane bending based on the present FE results. The proposed limit load solutions would be a basis of defective pipe bends and be useful to estimate non-linear fracture mechanics parameters based on the reference stress approach.

Limit Loads for Pipe Bends under Combined Pressure and in-Plane Bending Based on Finite Element Limit Analysis (압력과 모멘트의 복합하중을 받는 곡관에 대한 유한요소 한계하중 해석)

  • Oh C.S.;Kim Y.J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.401-402
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    • 2006
  • In the present paper, approximate plastic limit load solutions for pipe bends under combined internal pressure and bending are obtained from detailed three-dimensional (3-D) FE limit analyses based on elastic-perfectly plastic materials with the small geometry change option. The present FE results show that existing limit load solutions for pipe bends are lower bounds but can be very different from the present FE results in some cases, particularly for bending. Accordingly closed-form approximations are proposed for pipe bends under combined pressure and in-plane bending based on the present FE results. The proposed limit load solutions would be a basis of defective pipe bends and be useful to estimate non-linear fracture mechanics parameters based on the reference stress approach.

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Limit Loads for Piping Branch Junctions with Local Wall-thinning under Internal Pressure and In-plane Bending (감육이 존재하고 내압과 굽힘하중의 복합하중을 받는 T 분기관의 한계하중)

  • Han, Jae-Jun;Lee, Kuk-Hee;Kim, Yun-Jae;Lee, Sung-Ho;Park, Chi-Yong
    • Proceedings of the KSME Conference
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    • pp.299-304
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    • 2008
  • This paper presents plastic limit loads of piping branch junctions with local wall thinning under combined pressure and in-plane bending, based on systematic three-dimensional finite element limit analyses using elastic-perfectly plastic materials. An ideal branch junction without weld or reinforcement around the intersection is considered with two locations of wall thinning; one in the run pipe, and the other in the branch pipe. Based on FE results, effects of thinning geometries on plastic limit moments are quantified and simple approximations of plastic limit loads are proposed.

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Estimation of Critical Height of Embankment to Mobilize Soil Arching in Pile-supported Embankment (말뚝지지성토지반 내 지반아칭이 발달할 수 있는 한계성토고의 평가)

  • Hong, Won-Pyo;Hong, Seong-Won
    • Journal of the Korean Geotechnical Society
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    • v.26 no.11
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    • pp.89-98
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    • 2010
  • A method to design a critical height of embankments is presented so as to mobilize fully soil arching in pile-supported embankments. The behavior of the load transfer of embankment weights on pile cap beams was investigated by a series of model tests performed on pile-supported embankments with relatively wide space between cap beams. The model tests explained that the behavior of the load transfer depended very much on the height of embankments, because soil arching could be mobilized in pile-supported embankments only under enough high embankments. The measured vertical loads on cap beams coincided with the predicted ones estimated by the theoretical equations, which have been presented in the previous studies on the basis of load transfer mechanisms according to either the punching shear failure mode during low filling stage or the soil arching failure mode during high filling stage. The mechanism of the load transfer was shifted beyond a critical height of embankment from the punching shear mechanism to the soil arching mechanism. Therefore, in order to mobilize soil arching in pile-supported embankments, the embankments should be designed at least higher than the critical height. A theoretical equation to estimate the critical height could be derived by equalizing the vertical loads estimated by the load transfer mechanisms on the basis of both the punching shear and the soil arching. The derived theoretical equation could predict very well the experimental critical height of embankment.

Limit Loads for Circular Wall-Thinned Feeder Pipes Subjected to Bending and Internal Pressure. (원형 감육이 발생한 중수로 피더관의 한계하중 평가)

  • Je, Jin-Ho;Lee, Kuk-Hee;Chung, Ha-Joo;Kim, Jong-Sung;Kim, Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.11
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    • pp.1675-1680
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    • 2010
  • Flow Accelerated Corrosion (FAC) occurring during in-service conditions results in localized wall-thinning in the feeder pipes of CANDU. The wall-thinning of the feeder pipes is the main degradation mechanisms affecting the integrity of piping systems. In this paper, we assess the integrity of wall-thinned feeder pipes by limit load analysis. The limit loads for wall-thinning feeder pipes subjected to in-plane bending and internal pressure were determined on the basis of finte element limit analyses. The limit loads are determined from the results of limit analyses of elasticperfectly-plastic materials using the large geometry change. Closed-form approximations of limit load solutions for wall-thinning feeder pipes subjected to in-plane bending and pressure are proposed.

Evaluation of fire resistance according to load ratio and limit temperature (하중비와 한계온도에 의한 강구조 부재의 내화성능평가법 제안)

  • Kwon, In-Kyu;Kim, Heung-Youl
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • pp.395-399
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    • 2010
  • 강구조 부재의 내화성능평가를 위한 비재하가열시험은 강재 허용온도로 평가되고 있으나, 강재의 허용온도 설정은 H형강 부재의 최대하중로 평가되는 한계용도와 고온에서의 강소재의 허용응력도 능력으로 설정되었으므로 실지 작용되는 강구조 부재의 하중조건과 다양한 부재의 종류 등의 관점에서 허용온도의 적용은 다소 불합리한 점이 있다고 판단된다. 따라서 본 연구에서는 강구조 건축물에서의 부재에 작용하는 하중에 따른 내화성능의 차이를 보이고 이에 따른 합리적인 내화성능 평가방법을 제안하고자 한다.

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A Study on Development of Structural Health Monitoring System for Steel Beams Using Strain Gauges (변형률계를 이용한 강재보의 건전도 평가 시스템 개발에 관한 연구)

  • Hahn, Hyun Gyu;Ahn, Hyung Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.1
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    • pp.99-109
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    • 2012
  • This study aimed to develop a Structural Health Monitoring System for steel beams in the manner of suggesting and verifying a theoretical formula for displacement estimation using strain gauges, and estimating the loading points and magnitude. According to the results of this study, it was found that when a load of 160kN (56% of the yield load) was applied, the error rate of the deflection obtained with a strain gauge at the point of maximum deflection compared to the deflection measured with a displacement meter was within 2%, and that the estimates of the magnitude and points of load application also showed the error rate of not more than 1%. This suggests that the displacement and load of steel beams can be measured with strain gauges and further, it will enable more cost-effective sensor designing without displacement meter or load cell. The Structural Health Monitoring System program implemented in Lab VIEW gave graded warnings whenever the measured data exceeds the specified range (strength limit state, serviceability limit state, yield strain), and both the serviceability limit state and strength limit state could be simultaneously monitored with strain gauge alone.

인공위성 노치예측해석 및 정현파가진시험 입력도출

  • Kim, Sung-Hoon;Kim, Jin-Hee;Hwang, Do-Soon;Lee, Ju-Hun;Jin, Ik-Min
    • Aerospace Engineering and Technology
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    • v.1 no.2
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    • pp.75-82
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    • 2002
  • This paper presents a summary of the input data, requirements and notch prediction analysis for sinusoidal excitation test of a satellite. In the notch prediction analysis, the loads at excitation points and internal loads at the important locations on satellite structure were obtained. After checking of limit loads and margin of safety for each location, the notched sinusoidal test inputs were generated using the results of the notch prediction analysis.

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