• Title/Summary/Keyword: Hoop

Search Result 342, Processing Time 0.024 seconds

Weld Residual Stress According to the Ways of Heat Input in the Simulation of Weld Process using Finite Element Analysis (유한요소법을 이용한 용접공정 모사 시 입열 방법에 따른 용접잔류응력의 영향)

  • Yang, Jun-Seog;Park, Chi-Yong;Lee, Kyoung-Soo
    • Proceedings of the KSME Conference
    • /
    • 2008.11a
    • /
    • pp.98-103
    • /
    • 2008
  • This paper is to discuss distribution of welding residual stresses of a ferritic low alloy steel nozzle with dissimilar metal weld using Alloy 82/182. Two dimensional (2D) thermo-mechanical finite element analyses are carried out to simulate multi-pass welding process on the basis of the detailed and fabrication data. On performing the welding analysis generally, the characteristics on the heat input and heat transfer of weld are affected on the weld residual stress analyses. Thermal analyses in the welding heat cycle process is very important process in weld residual stress analyses. Therefore, heat is rapidly input to the weld pass material, using internal volumetric heat generation, at a rate which raises the peak weld metal temperature to $2200^{\circ}C$ and the base metal adjacent to the weld to about $1400^{\circ}C$. These are approximately the temperature that the weld metal and surrounding base materials reach during welding. Also, According to the various ways of appling the weld heat source, the predicted residual stress results are compared with measured axial, hoop and radial through-wall profiles in the heat affected zone of test component. Also, those results are compared with those of full 3-dimensional simulation.

  • PDF

Results and analyses for simulational round robin on welding residual stress prediction in nuclear power plant nozzle (원전 노즐 용접부 잔류응력 예측에 대한 유한요소 해석 Round Robin 결과 및 분석)

  • Song, Tae-Kwang;Bae, Hong-Yeol;Kim, Yun-Jae;Lee, Kyoung-Soo;Park, Chi-Yong;Yang, Jun-Seog;Huh, Nam-Su;Kim, Jong-Wook;Park, June-Soo;Song, Min-Sup;Lee, Seung-Gun;Kim, Jong-Sung;Yu, Seung-Cheon;Chang, Yoon-Suk
    • Proceedings of the KSME Conference
    • /
    • 2008.11a
    • /
    • pp.79-82
    • /
    • 2008
  • In this paper, results of simulational round robin test on residual stress prediction was provided. Welding residual stress is one of the reasons for primary water stress corrosion cracking in PWR. Therefore, quantifying the welding variables and defining the recommendation for prediction welding residual stress is important. Through the round robin test, it is known that compressive axial and hoop residual stress occurs in dissimilar metal weld and pre-existing residual stress distribution in dissimilar metal weld was affected by similar metal weld due to short length of safe end.

  • PDF

Composite action of hollow concrete-filled circular steel tubular stub columns

  • Fu, Qiang;Ding, Fa-xing;Zhang, Tao;Wang, Liping;Fang, Chang-jing
    • Steel and Composite Structures
    • /
    • v.26 no.6
    • /
    • pp.693-703
    • /
    • 2018
  • To better understand the influence of hollow ratio on the hollow concrete-filled circular steel tubular (H-CFT) stub columns under axial compression and to propose the design formula of ultimate bearing capacity for H-CFT stub columns, 3D finite element analysis and laboratory experiments were completed to obtain the load-deformation curves and the failure modes of H-CFT stub columns. The changes of the confinement effect between core concrete and steel tube with different hollow ratios were discussed based on the finite element results. The result shows that the axial stress of concrete and hoop stress of steel tube in H-CFT stub columns are decreased with the increase of hollow ratio. AfteGr the yield of steel, the reduction rate of longitudinal stress and the increase rate of circumferential stress for the steel tube slowed down. The confinement effect from steel tube on concrete also weakened slowly with the increase of hollow ratio. Based on the limit equilibrium method, a simplified formula of ultimate bearing capacity for the axially loaded H-CFT stub columns was proposed. The predicted results showed satisfactory agreement with the experimental and numerical results.

Numerical evaluation of buried composite and steel pipe structures under the effects of gravity

  • Toh, William;Tan, Long Bin;Tse, Kwong Ming;Raju, Karthikayen;Lee, Heow Pueh;Tan, Vincent Beng Chye
    • Steel and Composite Structures
    • /
    • v.26 no.1
    • /
    • pp.55-66
    • /
    • 2018
  • In this paper, the response of an underground fibreglass reinforced plastic (FRP) composite pipe system subjected to realistic loading scenarios that may be experienced by an actual buried pipeline is investigated. The model replicates an arbitrary site with a length of buried pipeline, passing through a $90^{\circ}$ bend and into a valve pit. Various loading conditions, which include effects of pipe pressurization, differences in response between stainless steel and fibreglass composite pipes and severe loss of bed-soil support are studied. In addition to pipe response, the resulting soil stresses and ground settlement are also analysed. Furthermore, the locations of potential leakage and burst have also been identified by evaluating the contact pressures at the joints and by comparing stresses to the pipe hoop and axial failure strengths.

Nonlinear Analysis of End-to-End Anastomosis Using Sub-modeling (Sub-modeling을 이용한 end-to-end 문합의 비선형 해석)

  • Han, Geun-Jo;Kim, Tae-Hyung;Ahn, Sung-Chan;Shim, Jae-Joon
    • Proceedings of the KSME Conference
    • /
    • 2001.06a
    • /
    • pp.877-882
    • /
    • 2001
  • A finite element analysis of end-to-end artery/PTFE anastomosis has been presented in this study to evaluate the distribution of compliance and stresses in the vicinity of the anastomosis due to any mismatch in compliance characteristics. The artery wall was assumed to be made of linear isotropic material in this simplified model and a nonlinear analysis and convergency study with respect to increasing meshed element numbers were performed with a mean artery pressure loading of the artery-PTFE model. Also, sub-modeling method was introduced to progress the accuracy of the finite element analysis. The results are as follow : 1. A hypercompliant zone on the artery side was observed around 4.0mm from the anastomosis and a high hoop stresses in the wall of artery and PTFE was dominent. 2. An artery displays large deformation so that nonlinear analysis and sub-modeling method was used. 3. An anastomosis with the thinner thickness and larger diameter PTFE (C type) could reduce the compliance disagreement.

  • PDF

Development and Clinical Application of a New Nitinol Stent (새로운 나이티놀 스텐트의 개발과 임상적용)

  • Park, S.S.;Kim, T.H.;Huh, S.J.;Song, H.Y.;Choi, S.P.;Kim, C.S.
    • Proceedings of the KOSOMBE Conference
    • /
    • v.1997 no.11
    • /
    • pp.343-346
    • /
    • 1997
  • A new type of stent was invented using a Nitinol wire. The hoop strength of the new stent was found to be 2 times larger than that of the Cragg or Memotherm stents. However, the longitudinal flexibility of the new stent was inferior to both the Cragg and Memotherm stents. This new stent seems to be useful or the treatment of stenosis with straight configuration, but need to be improved or use in tortuous stenotic region. The stent was applied to the patients with esophargeal stenosis and showed a good result.

  • PDF

Stress Distribution of Buried Concrete Pipe Under Various Environmental Conditions

  • Lee, Janggeun;Kang, Jae Mo;Ban, Hoki;Moon, Changyeul
    • Journal of the Korean GEO-environmental Society
    • /
    • v.17 no.12
    • /
    • pp.65-72
    • /
    • 2016
  • There are numerous factors that affect stress distribution in a buried pipe, such as the shape, size, and stiffness of the pipe, its burial depth, and the stiffness of the surrounding soil. In addition, the pipe can benefit from the soil arching effect to some extent, through which the overburden and surcharge pressure at the crown can be carried by the adjacent soil. As a result, the buried pipe needs to support only a portion of the load that is not transferred to the adjacent soil. This paper presents numerical efforts to investigate the stress distribution in the buried concrete pipe under various environmental conditions. To that end, a nonlinear elasto-plastic model for backfill materials was implemented into finite element software by a user-defined subroutine (user material, or UMAT) to more precisely analyze the soil behavior surrounding a buried concrete pipe subjected to surface loading. In addition, three different backfill materials with a native soil were selected to examine the material-specific stress distribution in pipe. The environmental conditions considering in this study the loading effect and void effects were investigated using finite element method. The simulation results provide information on how the pressures are redistributed, and how the buried concrete pipe behaves under various environmental conditions.

Design and Stress Analysis of 600 kJ SMES Model Coil (600 kJ SMES 모델 코일의 설계와 Stress 해석)

  • Park, Myung-Jin;Kwak, Sang-Yeop;Lee, Seoung-Wook;Kim, Woo-Seok;Hahn, Seoung-Young;Choi, Kyeong-Dal;Han, Jin-Ho;Lee, Ji-Kwang;Jung, Hyun-Kyo;Seong, Ki-Chul;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
    • /
    • 2006.07b
    • /
    • pp.871-872
    • /
    • 2006
  • 본 논문은 600 kJ SMES 모델 코일의 설계와 전자기력에 의한 모델코일의 스트레스의 해석에 관한 연구 결과를 나타낸다. 모델 코일의 설계에 적용된 초전도 선재는 77 K, 자기자계 하에서 115 A인 강화 선재이며, 모델 코일은 두 개의 팬케이크 코일로 구성한 모듈 코일 3개를 적층한 형태로 총 6개 더블 팬케이크 코일로 구성되어있다. 모델 코일의 임계전류는 전류를 인가하였을 때 코일에서의 최대 수직방향 자장을 이용해 Load Line을 나타내고, 이를 운전온도인 20 K에서의 $B-I_c$ 곡선에 적용하여 결정하였으며 236 A이다. 운전전류는 임계전류의 80%인 165 A로 결정하였으며, 이는 n-Value 손실을 고려한 값이다. 또한 해석적 방법을 이용해 코일에 전류를 인가하였을 때 전자기력에 의한 모델 코일의 radial stress와 hoop stress를 계산하여 나타내었다.

  • PDF

Analysis of Stress by Electromagnetic Force in a Small HTS Single Pancake Coil (소형 고온초전도 싱글 팬케이크 코일의 전자기력에 의한 Stress 해석)

  • Park, Myung-Jin;Kwak, Sang-Yeop;Lee, Seoung-Wook;Kim, Woo-Seok;Hahn, Seoung-Young;Choi, Kyeong-Dal;Han, Jin-Ho;Lee, Ji-Kwang;Jung, Hyun-Kyo;Seong, Ki-Chul;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
    • /
    • 2006.07b
    • /
    • pp.869-870
    • /
    • 2006
  • 일반적으로 초전도선재를 이용한 코일의 전자기력에 의한 스트레스 계산에 있어서는 코일의 전류밀도분포와 자속밀도분포의 선형적인 관계를 이용하나 아직까지 초전도체 특유의 비선형적인 특성을 이용한 스트레스의 계산은 미비하다. 본 논문에서는 13턴의 소형 싱글팬케이크 코일을 초전도의 특성을 적용해 해석하고 인가전류가 $0.3I_c,\;0.5I_c,\;0.8I_c$ 인 경우에 대해서 전자기력에 의한 코일의 스트레스를 유한요소법으로 계산하였다. 계산 결과 코일의 radial stress와 hoop stress는 모두 코일의 자속밀도분포와 유사한 모습을 나타내었다.

  • PDF

Higher order static analysis of truncated conical sandwich panels with flexible cores

  • Fard, Keramat Malekzadeh
    • Steel and Composite Structures
    • /
    • v.19 no.6
    • /
    • pp.1333-1354
    • /
    • 2015
  • A higher order analytical solution for static analysis of a truncated conical composite sandwich panel subjected to different loading conditions was presented in this paper which was based on a new improved higher order sandwich panel theory. Bending analysis of sandwich structures with flexible cores subjected to concentrated load, uniform distributed load on a patch, harmonic and uniform distributed loads on the top and/or bottom face sheet of the sandwich structure was also investigated. For the first time, bending analysis of truncated conical composite sandwich panels with flexible cores was performed. The governing equations were derived by principle of minimum potential energy. The first order shear deformation theory was used for the composite face sheets and for the core while assuming a polynomial description of the displacement fields. Also, the in-plane hoop stresses of the core were considered. In order to assure accuracy of the present formulations, convergence of the results was examined. Effects of types of boundary conditions, types of applied loads, conical angles and fiber angles on bending analysis of truncated conical composite sandwich panels were studied. As, there is no research on higher order bending analysis of conical sandwich panels with flexible cores, the results were validated by ABAQUS FE code. The present approach can be linked with the standard optimization programs and it can be used in the iteration process of the structural optimization. The proposed approach facilitates investigation of the effect of physical and geometrical parameters on the bending response of sandwich composite structures.