• Title/Summary/Keyword: incremental deformation

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Lateral deformation capacity and stability of layer-bonded scrap tire rubber pad isolators under combined compressive and shear loading

  • Mishra, Huma Kanta;Igarashi, Akira
    • Structural Engineering and Mechanics
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    • v.48 no.4
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    • pp.479-500
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    • 2013
  • This paper presents the experimental as well as analytical study conducted on layer-bonded scrap tire rubber pad (STRP) isolators to develop low-cost seismic isolators applicable to structures in developing countries. The STRP specimen samples were produced by stacking the STRP layers one on top of another with the application of adhesive. In unbonded application, the STRP bearings were placed between the substructure and superstructure without fastening between the contact surfaces which allows roll-off of the contact supports. The vertical compression and horizontal shear tests were conducted with varying axial loads. These results were used to compute the different mechanical properties of the STRP isolators including vertical stiffness, horizontal effective stiffness, average horizontal stiffness and effective damping ratios. The load-displacement relationships of STRP isolators obtained by experimental and finite element analysis results were found to be in close agreement. The tested STRP samples show energy dissipation capacity considerably greater than the natural rubber bearings. The layer-bonded STRP isolators serve positive incremental force resisting capacity up to the shear strain level of 150%.

A Study on the Angle of Localization of a Metal Specimen under Uniaxial Tension with Plane Strain Condition (평면 변형 조건에서 일축 인장력을 받는 금속 재료의 불연속 변위 각에 대한 연구)

  • Park, Jae-Gyun;Kim, Mi-Rim
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.3
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    • pp.275-281
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    • 2011
  • When a flat bar type metal specimen for general tension test is subject to incremental uniaxial tension, a narrow plastic shear band, so called luders band, is generated at some instance. This band typically has an angle to the axis of specimen and many early researches have been done to investigate the condition and angle of this localized deformation phenomenon by many researchers. This study follows the procedure of Thomas(1961) under plane stress boundary condition. $J_2$ plasticity theory, balance of linear momentum, and constitutive equations are used to derive the angle of luders band under plain strain boundary condition. The result was confirmed by other angle based on acoustic tensor theory.

Elasto-plastic Loading-unloading Nonlinear Analysis of Frames by Local Parameter Control (국부변수 조절을 통한 프레임의 탄소성 하중-제하 비선헝 해석)

  • 박문식
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.14 no.4
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    • pp.435-444
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    • 2001
  • Even todays, accurate and efficient algorithms for the large deformation analysis of elastoplastic frame structures lack due to the complexities of kinematics, material nonlinearities and numerical methods to cater for. The author suggests appropriate beam element based upon the incremental formulation from the 3D rod theory where Cauchy stress and engineering strain are variables to incorporate plasticity equations so that objectivity may be satisfied. A rectum mapping methods which can integrate and satisfy yield criteria efficiently is suggested and a continuation method which has global convergency and quadratic speed is developed as well. leading-unloading example problems are tested and the ideas are proved to be valuable.

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Fracture Analysis Based on the Critical-CTOA Criterion (임계 CTOA조건을 이용한 파괴해석)

  • 구인회
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.9
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    • pp.2223-2233
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    • 1993
  • An engineering method is suggested to calculate the applied load versus crack extension in the elastic-plastic fracture. The condition for an increment of crack extension is set by a critical increment of crack-up opening displacement(CTOD). The ratio of the CTOD increment to the incremental crack extention is a critical crack-tip opening angle(CTOA), assumed to be constant for a material of a given thickness. The Dugdale model of crack-tip deformation in an infinite plate is applied to the method, and a complete solution for crack extension and crack instability is obtained. For finite-size specimens of arbitrary geometry in general yielding, an approximate generalization of the Dugdale model is suggested so that the approximation approaches the small-scale yielding solution in a low applied load and the finite-element solution in a large applied load. Maximum load is calculated so that an applied load attains either a limit load on an unbroken ligament or a peak load during crack extension. The proposed method was applied to three-point bend specimens of a carbon steel SM45C in various sizes. Reasonable agreements are found between calculated maximum loads and experimental failure loads. Therefore, the method can be a viable alternative to the J-R curve approach in the elastic-plastic fracture analysis.

Ultimate Load Analysis of Axisymmetric Shells of Revolution Subjected to External Pressure (외압(外壓)을 받는 축대칭(軸對稱) Shell의 한계하중(限界荷重)에 관한 연구(硏究))

  • J.B.,Kim;C.Y.,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.20 no.4
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    • pp.1-8
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    • 1983
  • This paper describes the application of the finite element method to the large deflection elastic plastic analysis and ultimate load calculation of axisymmetric shell of revolution with initial imperfection subjected to external pressure. The nonlinear equilibrium equations are linearized by the successive incremental method and are solved by the combination of load increment and iteration scheme with considering plastic deformation theory. To get the more realistic effect of large deflection, corrected coordinats and directions of applied load ar every load increment steps are used. The effects of the plasticity, initial imperfection and the shape of shells on the ultimate load of clamped circular cap under external pressure are investigated. Consequently, the following conclusions are obtained; (1) At same geometric parameter $\lambda$, each shape of clamped circular caps yield same elastic ultimate loads in both cases, i.e. with and without initial imperfections, whereas, in the case of elastic-plastic state the shell becomes thicker, the ultimate loads are getting smaller. (2) The effects of initial imperfection to ultimate load are most significant in the elastic case and are more senstive in the elastic-plastic state with the thinner shells.

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Adjustment of Roll Gap for The Dimension Accuracy of Bar in Hot Bar Rolling Process (열간 선재 압연제품의 치수정밀도 향상을 위한 롤 갭 조정)

  • Kim, Dong-Hwan;Kim, Byung-Min;Lee, Young-Seog
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.6
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    • pp.96-103
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    • 2002
  • The objective of this study is to adjust the roll gap fur the dimension accuracy of bar in hot bar rolling process considering roll wear. In this study hot bar rolling processes fur round and oval passes have been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental from and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the effects of thermal softening of DCI (Ductile Cast Iron) roll material according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering curve. The new technique developed in this study for adjusting roll gap can give more systematically and economically feasible means to improve the dimension accuracy of bar with full usefulness and generality.

Rigid-Plastic FE Modeling of Frictional Contact Problems based on a Penalty Method (벌칙방법에 의한 마찰 접촉문제의 강소성 유한요소 모델링)

  • 장동환;황병복
    • Transactions of Materials Processing
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    • v.12 no.1
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    • pp.34-42
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    • 2003
  • This paper presents a rigid-plastic finite element method to handle the frictional contact problem between two deformable bodies experiencing large deformation. The variational formulation combined with incremental quasi-static model is employed for treating the contact boundary condition. The frictional behavior of the model obeys Coulomb's law of friction. The proposed contact algorithms are classified into two categories, one for searching contacting nodes and the other for calculating contact forces at the contact surface. A slave node and master contact segment are defined using the geometric condition of finite elements on the contact interface. The penalty parameter is used to limit the penetration between contacting bodies, and the finite elements are coupled with contact boundary elements.us gates and cavity thicknesses. Through this study we have observed that the jetting is related to the die swell of material. This means that the jotting is strongly affected by the elastic flow property rather than the viscous flow property in viscoelastic characteristics of molten polymer. Different resins have different elastic properties, and elastic flow behavior depends on the shear rate of flow, i.e. injection speed. Large die swell would eliminate jetting however, the retardation of die swell would stimulate jetting. In the point of mole design, reducing the thickness ratio of cavity to gate can reduce or eliminate jetting regardless of amount of elasticity of polymer melt.

Analysis of Failure Mechanism for Wire-woven Bulk Kaogme (Wire-woven Bulk Kagome 의 파손 메커니즘 분석)

  • Lee, Byung-Kon;Choi, Ji-Eun;Kang, Ki-Ju;Jeon, In-Su
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1690-1695
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    • 2007
  • Lightweight metallic truss structures with open, periodic cell are currently being investigated because of their multi-functionality such as thermal management and load bearing. The Kagome truss PCM has been proved that it has higher resistance to plastic buckling, more plastic deformation energy and lower anisotropy than other truss PCMs. The subject of this paper is an examination of the failure mechanism of Wire woven Bulk Kagome(WBK). To address this issue, the out-of-plane compressive responses of the WBK has been measured and compared with theoretical and finite element (FE) predictions. For the experiment, 2 multi-layered WBK are fabricated and 3 specimens are prepared. For the theoretical analysis, the brazed joints of each wire in WBK are modeled as the pin-joint. Then, the peak stress of compressive behavior and elastic modulus are calculated based on the equilibrium equation and energy method. The mechanical structure with five by five cells on the plane are constructed is modeled using the commercial code, PATRAN 2005. and the analysis is achieved by the commercial FE code ABAQUS version 6.5 under the incremental theory of plasticity.

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Adjustment of Roll Gap for the Dimension Accuracy of Bar in Hot Bar Rolling Process

  • Kim, Dong-Hwan;Kim, Byung-Min;Lee, Youngseog
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.1
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    • pp.56-62
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    • 2003
  • The objective of this study is to adjust the roll gap for the dimension accuracy of bar in hot bar rolling process considering roll wear. In this study hot bar rolling processes for round and oval passes have been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental form and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the effects of thermal softening of DCI (Ductile Cast Iron) roll material according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering curve. The new technique developed in this study for adjusting roll gap can give more systematically and economically feasible means to improve the dimension accuracy of bar with full usefulness and generality.

Development of Technique Predicting of the Wear of DCI Roll Using Carbon Steel in Hot Rod Rolling Process (탄소강 선재 압연공정의 DCI 롤 마멸 예측 기술의 개발)

  • Kim, Dong-Hwan;Kim, Byeong-Min;Lee, Yeong-Seok;Yu, Seon-Jun;Ju, Ung-Yong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.9
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    • pp.1736-1745
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    • 2002
  • The objective of this study is to predict the roll wear in hot rod rolling process. In this study hot rod rolling process for round and oval passes has been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental form and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the thermal softening of DCI (Ductile Cast Iron) roll according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering parameter curve. 3D wear program developed in this study might be used for adjusting the gap of rolls to set up a suitable rolling schedule for keeping dimensional tolerance of the product.