• Title/Summary/Keyword: Thermo elasto-plastic analysis

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A Study on the Distortion Control Characteristics of the STS 304 Multi-pass Butt Weldment by Tensioning Method (인장하중법에 따른 STS 304 다층 맞대기 용접부의 변형 제어 특성에 관한 연구)

  • Kim, Ha-Geun;Lee, Dong-Ju;Shin, Sang-Beom
    • Journal of Welding and Joining
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    • v.28 no.3
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    • pp.73-78
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    • 2010
  • The purpose of this study is to develop the control technology of the welding distortion caused by Auto NG-GTA(Narrow Gap-GTA) welding process at the STS 304 multi-pass butt weldment. Heat input model for Auto NG-GTA welding process was established and verified by measuring temperature change and molten pool shape at the bead-on-plate weldment. With the heat input model developed, the effect of tension load on the welding distortion at the STS 304 multi-pass butt weldment was evaluated using the thermo-elasto-plastic FE analysis. In accordance with FEA results, the angular distortion and transverse shrinkage sharply decreased with an increase in tension load. This result indicated that tensioning method was an effective countermeasure against the welding distortion of the STS 304 multi-pass butt weldment.

Study on the Deformation Behavior by Spot Heating for thin plate (박판 점 곡직 시 변형 특성에 관한 연구)

  • Jang, Gyeong-Bok;Park, Jung-Gu;Jo, Si-Hun;Jang, Tae-Won
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.285-287
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    • 2005
  • During fabrication of deck house block in passenger ships, the problem of unexpected large deformation and distortion frequently occurs. In this case, line and spot heating method were widely used to correct the distortion of thin plate structure. Spot heating was especially used for the case under 5mm thickness. Few papers are available on the working conditions of spot heating method but only little information on deformation control. In this study, evaluation was carried out on the temperature distribution of spot heating methods using FEA and practical experiments for various heating time. IIn FEA, heat input model was established using Tsuji's double Gaussian heat input mode (Tsuji, I., 1988). This model was verified by comparing with experimental data. Also radial shrinkage and angular distortion due to spot heating were determined and compared with experimental results. Thermo elasto-plastic analysis was performed using commercial FE code, MSC/MARC. Radial shrinkage and angular distortion were measured using 3D measuring apparatus. Based on these results, simplified analysis model for deformation by spot heating was established.

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A Study on the Distortion Control Characteristics of the STS 304 Multi-pass Butt Weldment by the Tensioning Method (인장하중법에 따른 STS 304 다층 맞대기 용접부의 변형 제어 특성에 관한 연구)

  • Kim, Ha-Keun;Lee, Dong-Ju;Shin, Sang-Beom
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.101-101
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    • 2009
  • The purpose of this study is to develop the control technology of the welding distortion caused by Auto NG-GTA welding process at the STS 304 multi-pass butt weldment. For it, heat input model for Auto NG-GTA welding process was established and verified by measuring temperature change and molten pool shape at the bead-on-plate weldment. With heat input model developed, the effect of the tension load on the amount of welding distortion at the STS 304 multi-pass butt weldment was evaluated using the thermo-elasto-plastic FE analysis. In accordance with FEA results, the angular distortion and transverse shrinkage sharply decreased with an increase in tension load. This result indicates that tensioning method was verified as a countermeasure against the welding distortion of STS 304 multi-pass butt weldment.

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A Study on Fatigue Life Prediction of Welded Joints Through Fatigue Test and Crack Propagation Analysis (피로실험 및 균열진전 해석을 통한 용접부의 피로수명 예측에 관한 연구)

  • Y.C. Jeon;Y.I. Kim;J.K. Kang;J.M. Han
    • Journal of the Society of Naval Architects of Korea
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    • v.38 no.3
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    • pp.93-106
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    • 2001
  • T-joint and hopper knuckle joint models are typical welded joints in ship structure, which are very susceptible to fatigue damage under service condition. Fatigue test and fracture mechanical analysis were performed on these joints to find out characteristics of fatigue behavior. Unified S-N curve was developed from the test results of these two types of joint using hot spot stress concept, and also propagation life was also estimated using Paris' crack propagation law. Residual stress effect on propagation life was considered in calculating propagation life, as was done with thermo-elasto-plastic FE analysis and residual stress intensity factor calculation. Fatigue life of similar kinds of welded joint could be predicted with this unified S-N curve and fracture mechanical analysis technique.

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3D Finite Element Simulation of Pellet-Cladding Mechanical Interaction (3차원 유한요소를 이용한 핵연료와 피복관 기계적 거동 해석)

  • Seo, Sang Kyu;Lee, Sung Uk;Lee, Eun Ho;Yang, Dong Yol;Kim, Hyo Chan;Yang, Yong Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.5
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    • pp.437-447
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    • 2016
  • In a nuclear power plant, the fuel assembly, which is composed of fuel rods, burns, and the high temperature can generate power. The fuel rod consists of pellets and a cladding that covers the pellets. It is important to understand the pellet-cladding mechanical interaction with regard to nuclear safety. This paper proposes simulation of the PCMI. The gap between the pellets and the cladding, and the contact pressure are very important for conducting thermal analysis. Since the gap conductance is not known, it has to be determined by a suitable method. This paper suggests a solution. In this study, finite element (FE) contact analysis is conducted considering thermal expansion of the pellets. As the contact causes plastic deformation, this aspect is considered in the analysis. A 3D FE module is developed to analyze the PCMI using FORTRAN 90. The plastic deformation due to the contact between the pellets and the cladding is the major physical phenomenon. The simple analytical solution of a cylinder is proposed and compared with the fuel rod performance code results.