• Title/Summary/Keyword: Elastic Pipe

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Experimental study on pullout capacity on friction type steel pipe rock bolt to use elastic restoring force and existing rock bolts (탄성복원력을 이용한 마찰형 강관 록볼트 및 기존 록볼트에 대한 인발력 실험연구)

  • Moorak Son;Jihyun Kim
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.6
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    • pp.459-468
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    • 2023
  • In this study, an experiment on pullout capacity was conducted of rock bolts using grouting materials such as cement mortar and resin, which are widely used, and a newly proposed steel pipe friction type rock bolt using elastic restoring force, and the results were compared and analyzed. The experimental results showed that the pullout capacity on the rock bolts with cement mortar under a dry condition (no ground water) was relatively larger than the rock bolts with resin and the steel pipe. Nevertheless, the friction type steel pipe rock bolt to use elastic restoring force is expected to be useful in the field particularly where groundwater exists and it affects the loss and curing of grouting materials such as cement mortar or resin. In addition, it was found to have the advantage of being easy and quick to install.

Behavior of Buried Pipe under Embankment (성토하에 매설된 관의 거동)

  • 강병희;윤유원
    • Geotechnical Engineering
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    • v.4 no.1
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    • pp.49-58
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    • 1988
  • The stresses on the buried steel pipe under embankment are analysed by the elasto-plastic theory using FEM to study the influences of the geometry of soil-conduit pipe system and the elastic modulus of the fill on the pipe responses . The geometry of the system considered in this study includes the height of embankment, the thickness of the pipe, and the width and the depth of the trench . By comparing the stresses computed by Marston-Spangler's pipe theory with those obtained from the elasto-plastic theory, Marston-Spangler's theory was discussed and analysed . It is found that the stress distribution around the pipe by elasto- plastic analysis is similar to that by Spangler's flexible pipe theory when the geometrical ratio (diameter/thickness) of the steel pipe is 400. And Spangler's flexible pipe theory does not seem to be suitable to analyse the buried steel pipe of which the geometrical ratio is lower than 200. The vertical loads by the rigid pipe theory are always larger than those by the flexible pipe theory regardness of the variations in the geometry of soil-conduit pipe system considered above and the elastic modulus of the fill.

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Analysis of the Elbow Thickness Effect on Crack Location and Propagation Direction via Elastic-Plastic Finite Element Analysis (탄소성 유한요소 해석을 통한 곡관 두께에 따른 파손 위치 및 균열 진전 방향 분석)

  • Jae Yoon Kim;Jong Min Lee;Yun Jae Kim;Jin Weon Kim
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.18 no.1
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    • pp.26-35
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    • 2022
  • When piping system in a nuclear power plant is subjected to a beyond design seismic condition, it is important to accurately determine possibility of crack initiation and, if initiation occurs, its location and time. From recent experimental works on elbow pipes, it was found that the crack initiation location and crack propagation direction of the SA403 WP316 stainless steel elbow pipe were affected by the pipe thickness. In this paper, the crack initiation location and crack propagation direction for SA403 WP316 stainless steel elbow pipes with different thickness were analyzed via elastic-plastic finite element analysis. Based on FE results, the effect of the pipe thickness on different crack initiation location and crack propagation direction was analyzed using ovality, stress and strain components. It was also confirmed that the presence of internal pressure had no effect on the crack initiation location and crack propagation direction.

Plastic loads of pipe bends under combined pressure and out-of-plane bending (면외 굽힘하중과 내압의 복합하중을 받는 곡관의 소성하중)

  • Lee, Kuk-Hee;Kim, Yun-Jae;Park, Chi-Yong;Lee, Sung-Ho;Kim, Tae-Ryong
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1836-1841
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    • 2007
  • Based on three-dimensional (3-D) FE limit analyses, this paper provides plastic limit and TES(Twice-Elastic-Slope) loads for pipe bends under combined pressure and out-of-plane bending. The plastic limit loads are determined from FE limit analyses based on elastic-perfectly-plastic materials using the small geometry change option, and the FE limit analyses using the large geometry change option provide TES plastic loads. A wide range of parameters related to the bend geometry is considered. Based on the FE results, closed-form approximations of plastic limit and TES plastic load solutions for pipe bends under out-of-plane bending are proposed.

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Closed-Form Plastic Collapse Loads of Pipe Bends Under Combined Pressure and In-Plane Bending (압력과 모멘트의 복합하중을 받는 곡관의 소성 붕괴하중 예측식 개발)

  • Oh Chang-Sik;Kim Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.8 s.251
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    • pp.1008-1015
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    • 2006
  • Based on three-dimensional (3-D) FE limit analyses, this paper provides plastic limit, collapse and instability load solutions for pipe bends under combined pressure and in-plane bending. The plastic limit loads are determined from FE limit analyses based on elastic-perfectly plastic materials using the small geometry change option, and the FE limit analyses using the large geometry change option provide plastic collapse loads (using the twice-elastic-slope method) and instability loads. For the bending mode, both closing bending and opening bending are considered, and a wide range of parameters related to the bend geometry is considered. Based on the FE results, closed-form approximations of plastic limit and collapse load solutions for pipe bends under combined pressure and bending are proposed.

Finite Element Based Stress Concentration Factors for Pipes with Local Wall Thinning (유한요소해석을 이용한 국부 감육배관에 대한 응력집중계수 제시)

  • Son, Beom-Goo;Kim, Yun-Jae;Kim, Young-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.7
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    • pp.1014-1020
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    • 2004
  • The present work complies the elastic stress concentration factor for a pipe with local wall thinning, based on detailed three-dimensional elastic FE analysis. To cover practically interesting cases, a wide range of pipe and defect geometries are considered, and both internal pressure and global bending are considered. Resulting values of stress concentration factors are tabulated for practical use, and the effect of relevant parameters such as pipe and defect geometries on stress concentration factors are discussed. The present results would provide valuable information to estimate fatigue damage of the pipe with local wall thinning under high cycle fatigue.

Buckling Behavior of Corrugated Steel Pipe under External Uniform Pressure (등분포하중을 받는 파형강관의 좌굴거동)

  • Ahn, Woo Cheul;Han, Taek Hee;Lim, Nam Hyoung;Kang, Young Jong
    • Journal of Korean Society of Steel Construction
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    • v.15 no.1
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    • pp.33-40
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    • 2003
  • There are two basic concepts about concerning the buckling analysis of a buried pipe. One concept considers the soil around the pipe asn elastic continuum mediaum. The other concept holds that the pipe is sup ported by an elastic spring, which replaces the effects of the surrounding soil (the Winkler model). Theise buckling analysis is based on plane analysis, without considering the corrugation effect and the length effect. This paper thus presents a parametric study using the Finite Element Method (FEM) for the Winker model and proposes a buckling strength formula after examining a 3D analysis considering the corrugation effect and the length effect, thatwhichhelp in estimating the critical buckling strength of such CSP

A Study on the Bending Process for Precision Pipe Forming (정밀 파이프 성형을 위한 벤딩 공정 개발에 관한 연구)

  • Kim, Hyun-Jin;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.6
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    • pp.58-65
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    • 2007
  • The arbitrarily-bended pipe is widely used in a heat exchanger system. Thus, the pipe bending process has important role in performance and productivity of heat exchanger system. The purpose of this study is to investigate the bending process for manufacturing of sound pipe. And, the spring-back effect and the variation of pipe thickness should be controlled effectively. The change of spring-back ratio and the thickness variation of pipe according to the change of bending radius, bending angle and pipe thickness are analyzed by FEM analysis. The analytic results are compared with the experimental data, accordingly the results show good agreement. The method of the analysis can be applied for manufacturing of precision bended pipe.

Ramifications of Structural Deformations on Collapse Loads of Critically Cracked Pipe Bends Under In-Plane Bending and Internal Pressure

  • Sasidharan, Sumesh;Arunachalam, Veerappan;Subramaniam, Shanmugam
    • Nuclear Engineering and Technology
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    • v.49 no.1
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    • pp.254-266
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    • 2017
  • Finite-element analysis based on elastic-perfectly plastic material was conducted to examine the influence of structural deformations on collapse loads of circumferential through-wall critically cracked $90^{\circ}$ pipe bends undergoing in-plane closing bending and internal pressure. The critical crack is defined for a through-wall circumferential crack at the extrados with a subtended angle below which there is no weakening effect on collapse moment of elbows subjected to in-plane closing bending. Elliptical and semioval cross sections were postulated at the bend regions and compared. Twice-elastic-slope method was utilized to obtain the collapse loads. Structural deformations, namely, ovality and thinning, were each varied from 0% to 20% in steps of 5% and the normalized internal pressure was varied from 0.2 to 0.6. Results indicate that elliptic cross sections were suitable for pipe ratios 5 and 10, whereas for pipe ratio 20, semioval cross sections gave satisfactory solutions. The effect of ovality on collapse loads is significant, although it cancelled out at a certain value of applied internal pressure. Thinning had a negligible effect on collapse loads of bends with crack geometries considered.

Stress Fields Along Semi-Elliptical Interfacial Crack Front with Yield-Strength-Mismatch (항복강도 불일치 반타원 계면균열 선단에서의 응력장)

  • Choi, Ho-Seung;Lee, Hyung-Yil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.1
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    • pp.126-137
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    • 2003
  • Many research works have been performed on the J-T approach for elastic-plastic crack-tip stress fields in a variety of plane strain specimens. To generalize the validity of J-T method, further investigations are however needed fur more practical 3D structures than the idealized plane strain specimens. The present study deals mainly with 3D finite element (FE) modeling of welded plate and straight pipe, and accompanying elastic, elastic-plastic FE analyses. Manual 3D modeling is almost prohibitive, since the models contain semi-elliptical interfacial cracks which require singular elements. To overcome this kind of barrier, we develop a program generating the meshes fur semi-elliptical interfacial cracks. We then compare the detailed 3D FE stress fields to those predicted with J-T two parameters. The validity of J-T approach is thereby extended to 3D yield-strength-mismatched weld joints, and useful information is inferred fur the design or assessment of pipe welds.