• Title/Summary/Keyword: Plastic analysis method

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Finite Element Analysis of a Cold Forging Process Having a Floating Die (부유금형을 가진 냉간단조 공정의 유한요소해석)

  • 류찬호;전만수
    • Transactions of Materials Processing
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    • v.9 no.2
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    • pp.159-164
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    • 2000
  • In this paper, a computer simulation technique for the forging process having a floating die is presented. The penalty rigid-plastic finite element method is employed together with an iteratively force-balancing method, in which the convergence is achieved when the floating die part is in force equilibrium within the user-specified tolerance. The force balance is controled by adjusting the velocity of the floating die in an automatic manner. An application example of a three-stage cold forging process is given.

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3-D Analysis of Hot Forging Processes using the Mesh Compression Method (격자압축법을 이용한 3차원 단조공정해석)

  • Hong, J.T.;Yang, D.Y.
    • Proceedings of the KSME Conference
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    • 2001.06c
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    • pp.492-497
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    • 2001
  • In the finite element analysis of metal forming processes using general Lagrangian formulation, element nodes in the mesh move and elements are distorted as the material is deformed. The excessive degeneracy of mesh interrupts finite element analysis and thus increases the error of plastic deformation energy. In this study, a remeshing scheme using so-called mesh compression method is proposed to effectively analyze the flash which is generated usually in hot forging processes. In order to verify the effectiveness of the method, several examples are tested in two-dimensional and three-dimensional problems.

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A Study on the Prediction and Control of Angular Distortion in Thick Weldments (후판 구조의 각변형 예측 및 제어에 관한 연구)

  • Kim, Sang-Il
    • Journal of Ocean Engineering and Technology
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    • v.22 no.6
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    • pp.100-105
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    • 2008
  • The block assembly of ship consists of a series of heat processes such as cutting, bending, welding residual stress relaxation and fairing With the fast development of computers, the thermal elasto-plastic analysis method has become a versatile tool for practical applications in the ship production. If numerical analysis is proved to be an advantageous tool to predict the residual deformation due to various heat processes, the optimum methods which can remove the welding distortion can be presented at each assembly stage, which will result in great progress in improving the accuracy of block assembly. In order to minimize the weld-induced angular distortion in thick weldments, this paper proposes the optimum groove design for various plate thickness as the distortion control method. The validity of this method has been substantiated by a number of numerical simulations and experiments.

A Case Study of Analysis and Design for the Tunnel Stablization in Fault Zone by FRP Reinforced Grouting Method (FRP보강 그라우팅에 의한 단층대의 터널 안정성 분석 및 설계 사례 연구)

  • 박종호;최용기;박영목;권오엽;이재봉
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.121-128
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    • 2001
  • This is a case study of stability analysis and reinforcement design for the tunnel where the collapse of the entrance slops occured along the fault zone developed in the bed rock. According to the site investigation, the main factor of sliding is the influence of fault gouge and heavy rainfall. Considering the in-situ condition, the versatile reinforcement methods is needed, and so the close investigation on the site area was accompanied with the stability analysis of tunnel and slops. The FRP(Fiberglass reinforced plastic) grouting method improved the defect of Steel Umbrella Arch Method, such as oxidation, low work efficiency, the material's heavy weight, is adapted as the reinforcement methods.

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Improved refined plastic hinge analysis accounting for local buckling and lateral-torsional buckling

  • Thai, Huu-Tai;Kim, Seung-Eock;Kim, Jongmin
    • Steel and Composite Structures
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    • v.24 no.3
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    • pp.339-349
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    • 2017
  • In this paper, a conventional refined plastic hinge analysis is improved to account for the effects of local buckling and lateral-torsional buckling. The degradation of flexural strength caused by these effects is implicitly considered using practical LRFD equation. The second-order effect is captured using stability functions to minimize modeling and solution time. An incremental-iterative scheme based on the generalized displacement control method is employed to solve the nonlinear equilibrium equations. A computer program is developed to predict the second-order inelastic behavior of space steel frames. To verify the accuracy and efficiency of the proposed program, the obtained results are compared with the existing results and those generated using the commercial finite element package ABAQUS. It can be concluded that the proposed program proves to be a reliable and effective tool for daily use in engineering design.

Analysis of plastic deformation through axisymmetric backward extrusion using upper-bound method (上界解法에 의한 軸對稱 後方押出의 塑性變形 解析)

  • 한철호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.3
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    • pp.330-336
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    • 1989
  • In analyzing the axisymmetric backward extrusion process a new method of analysis using upper-bound theorem is proposed in which the plastic zone and dead metal zone cam be predicted. Experiments are carried out with commercial aluminum. The metal flow on the meridional plane has been visualized experimentally by using the gridded specimens. It is shown that the theoretical results both in extrusion load and deformation pattern are in good agreement with the experimental results and they can be used for effective punch and die design to consider various process parameters in axisymmetric backward extrusion.

A Study on the Fault Process and Equipment Analysis of Plastic Ball Grid Array Manufacturing Using Data-Mining Techniques

  • Sim, Hyun Sik
    • Journal of Information Processing Systems
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    • v.16 no.6
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    • pp.1271-1280
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    • 2020
  • The yield and quality of a micromanufacturing process are important management factors. In real-world situations, it is difficult to achieve a high yield from a manufacturing process because the products are produced through multiple nanoscale manufacturing processes. Therefore, it is necessary to identify the processes and equipment that lead to low yields. This paper proposes an analytical method to identify the processes and equipment that cause a defect in the plastic ball grid array (PBGA) during the manufacturing process using logistic regression and stepwise variable selection. The proposed method was tested with the lot trace records of a real work site. The records included the sequence of equipment that the lot had passed through and the number of faults of each type in the lot. We demonstrated that the test results reflect the real situation in a PBGA manufacturing process, and the major equipment parameters were then controlled to confirm the improvement in yield; the yield improved by approximately 20%.

Effect of Strength Parameter a in the Generalized Hoek-Brown Failure Criterion and the Reinforcement Thickness on the Elasto-plastic Behavior of Circular Tunnel (일반화된 Hoek-Brown 파괴조건식의 강도정수 a와 터널 보강깊이가 원형터널의 탄소성 거동에 미치는 영향)

  • Lee, Youn-Kyou;Park, Kyung-Soon
    • Explosives and Blasting
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    • v.26 no.2
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    • pp.20-28
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    • 2008
  • In the design stage of a tunnel, the wall convergence is commonly estimated through an elasto-plastic analysis of the tunnel, which has been a topic drawing many researcher's attention so far. Despite its importance, however, the elasto-plastic behavior of a circular tunnel excavated in a generalized Hoek-Brown rockmass is still poorly understood. In this study, a simple munerical method based on Lee & Pietruszczak (2008) for the elasto-plastic analysis of a circular tunnel surrounded by reinforced annulus is proposed. It is assumed that the tunnel is excavated in a strain-softening rockmass obeying the generalized Hoek-Brown failure condition. The commercial code FLAC is used for the verification of the proposed method. The influence of the Hoek-Brown strength parameter a and the thickness of the reinforcement annulus on the elasto-plastic behavior around the tunnel was discussed by conducting some example analyses. The results show that the influence of these two parameters on the distribution of stresses and displacements is substantial.

A Study of Predicting Method of Residual Stress Using Artificial Neural Network in $CO_2$Arc welding

  • Cho, Y.;Rhee, S.;Kim, J.H.
    • International Journal of Korean Welding Society
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    • v.1 no.2
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    • pp.51-60
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    • 2001
  • A prediction method for determining the welding residual stress by artificial neural network is proposed. A three-dimensional transient thermo-mechanical analysis has been performed for the $CO_2$ arc welding using the finite element method. The first part of numerical analysis performs a three-dimensional transient heat transfer analysis, and the second part then uses the results of the first part and performs a three-dimensional transient thermo-elastic-plastic analysis to compute transient and residual stresses in the weld. Data from the finite element method are used to train a back propagation neural network to predict the residual stress. Architecturally, the fully interconnected network consists of an input layer for the voltage and current, a hidden layer to accommodate the failure mechanism mapping, and an output layer for the residual stress. The trained network is then applied to the prediction of residual stress in the four specimens. It is concluded that the accuracy of the neural network predicting method is fully comparable with the accuracy achieved by the traditional predicting method.

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Simplified Collapse Analysis of Ship Transverse Structures (선체 횡구조물의 단순화된 최종 강도 해석)

  • P.D.C.,Yang
    • Bulletin of the Society of Naval Architects of Korea
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    • v.26 no.4
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    • pp.57-66
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    • 1989
  • In this paper, a theory for the static analysis of large plastic deformations of 3-dimensional frames, aiming at application to the collapse analysis of ship structures, is presented. In the frame analysis formulation, effects of shear deformations are included. A plastic hinge is inserted into the field of a beam end, and post. failure deformation of the plastic hinge is characterized by finite rotations and extensions. In order to model deep web frames of ship's structures into a framed structures, collapse of thin-walled plate girders is investigated. The proposed analysis method is applied to several ship structural models in the references.

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