• Title/Summary/Keyword: Residual Deformation

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Application of Tensioning Method to Deformation Control of Thin Plate Fillet Weld (박판 필릿용접시 변형제어를 위한 장력법 적용)

  • Lee, Joo-Sung;Park, Jae-Woo
    • Journal of Ocean Engineering and Technology
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    • v.22 no.1
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    • pp.64-69
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    • 2008
  • As it has been well appreciated from the viewpoint of efficiency, The weld-induced deformation control is one of the most important issues in marine structure production. In the case of thin plate block, weld-induced deformation is more serious than in the case of relatively thick plate block. The heat affect zone of thin plates is wider than that of thick plates with the same heat input. Among weld-induced deformations, the buckling deformation by the shrinkage and residual stress in the weld line direction is one of the most serious deformation types. This paper is concerned with controlling buckling deformations for the thin plate fillet welds, by using the tensioning method. A numerical analysis was carried out to illustrate several dominant buckling modes due to compressive residual stress in the fillet weldsof thin plates. Then, weld tests were carried out for 20 specimens with varying plate thickness, and with different magnitudes and directions for the tension load. The results graphically represented to shaw the effect of the tensioning method in reducing the weld-induced deformation. From the present findings, it was seen that the tensioning method is a useful way to control weld-induced deformations in the fillet welds of thin plates.

Investigation into a Chemical Cracking and the Measurement of Stress in a Polycarbonate Specimen through Deformation Jig (변형지그를 이용한 폴리카보네이트 시편의 케미컬 크랙킹 및 응력측정에 관한 연구)

  • Yoo, Seo Jeong;Hong, Hyoung Sik;Lyu, Min-Young
    • Polymer(Korea)
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    • v.38 no.5
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    • pp.645-649
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    • 2014
  • The causes of residual stress in an injection molded part are high temperature variation and shear stress during molding process. Chemical cracking test is one of the methods of measuring residual stress and cracks are developed according to the degree of residual stress. In this study, the relationship between chemical cracking and exerted stress have been investigated. Deformation jig was designed and used to give a stress through deformation in a specimen. Specimens were molded by a hot press using polycarbonate (PC) and annealed to remove residual stresses in the specimens. Specimens were fixed in the deformation jig and immersed into the solvent to create cracks in the specimens. Solvents were prepared by using tetrahydrofuran and methyl alcohol. As stress accordance with the deformation in the specimen increased, the frequency and density of cracks in the specimen also increased. The results of this study can be used for the measurement of residual stress quantitatively in an injection molded PC product using a chemical cracking method.

A Fundamental Study on Forecast of the Thin Plate Welding Deformation by Numerical Simulation (수치시뮬레이션에 의한 박판 용접 변형 예측에 관한 기초적 연구)

  • 김종명;박창수;김영표;방한서
    • Journal of Welding and Joining
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    • v.21 no.1
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    • pp.93-98
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    • 2003
  • For construction of steel structures, thin steel plates have been often used and welding is the main manufacturing process. However, welding processes cause some problems(welding residual stresses, welding deformations, etc.). In these problems, welding deformation is extremely harmful to the safety of structures especially. Therefore, in this study, a numerical analysis program based on large deformation plate theory has been developed to analyze and predict the welding deformation in thin plates. From the result of numerical analyse, we can find two parameters, thermal cycles and mechanical restraints affecting the welding deformation of structures. It is considered that large difference of thermal cycles and mechanical restraints in the width direction bring about welding deformation. Results of simulation have the same tendency of deformation distribution in width direction as experimental formulas.

Effects by Applying Mode of Single Overload on Propagation Behavior of Fatigue Crack (단일과대하중의 작용모드가 피로균열의 전파거동에 미치는 영향)

  • 송삼홍;이정무
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.6
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    • pp.109-116
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    • 2004
  • In this study, when variable-amplitude load with various applying mode acts on the pre-crack tip, we examined how fatigue cracks behave. Hence aspects of the deformation caused by changing the applying mode of single overload and propagation behavior of fatigue crack were experimentally examined: What kinds of the deformation would be formed at pre-crack and its tip\ulcorner What aspects of the residual plastic deformation field would be formed in front of a crack\ulcorner How aspects of the plastic zone could be evaluated\ulcorner As applying mode of single overloading changes, the deformation caused by tensile and shear loading variously showed in each applying mode. The different aspects of deformation make influence on propagation behavior of cracks under constant-amplitude fatigue loading after overloading with various modes. We tried to examine the relationship between aspects of deformation and fatigue behavior by comparing the observed deformation at crack and crack propagation behavior obtained from fatigue tests.

Theoretical Approach to Welding Out-of Plane Oeformations in Thin Plate Structures (박판구조물의 용접 면외변형에 대한 이론 해석적 접근)

  • Seo, Sung-Il
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.5 s.143
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    • pp.466-471
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    • 2005
  • The out-of-plane deformation in thin plate structure has been a serious qualify problem. It has been known that the out-of-plane deformation is caused by the angular deformation of welded joint. However, experimental results show that the conventional theory based on angular deformation is not appropriate for prediction of the out-of-plane deformation in thin plate structure. In this study, large deformation plate theory is introduced to clarify the effect of residual stress on the out-of-plane deformation. A simple equation is proposed to predict the out-of-plane deformation. The results by the proposed method show good agreement with the experimental results.

Prediction of Steady-state Strip Profile during Hot Rolling - PartⅡ: Development of a Mathematical Model (열연 공정 정상상태 판 프로파일 예측 - PartⅡ: 수식 모델 개발)

  • Lee, J. S.;Hwang, S. M.
    • Transactions of Materials Processing
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    • v.25 no.1
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    • pp.61-66
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    • 2016
  • In the current study, we present a new model for the prediction of the strip profile and the residual stresses. This new approach is an analytical model that predicts the residual stresses from the effect of post-deformation. Since the residual stress cannot exceed the yield strength of the material, post-yielding may possibly occur in the post-deformation zone prior to the strip reaching the steady-state zone. The prediction accuracy of the proposed model is examined through comparison with the predictions from 3-D finite element (FE) simulations.

Effect of Peening on Low Temperature Fatigue Strength Behavior of STABILIZER BAR in Suspension Material (현가장치 STABILIZER BAR의 저온피로강도에 미치는 쇼트피닝의 영향)

  • Jung, Jae-Wook;Park, Keyoung-Dong
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.353-358
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    • 2004
  • We got the following characteristics from fatigue crack growth test carried out in the environment of room temperature and low temperature at $25^{circ}C$, $-60^{circ}C$, $-80^{circ}C$, and $-100^{circ}C$ in the range of stress ratio of 0.3 by means of opening mode displacement. And there is a difference between shot peened specimen and unpeened specimen. The purpose of this study is to predict the behavior of fatigue crack propagation as one of fracture mechanics on the compressive residual stress. Fatigue crack growth rate of shot peened metal was lower than that of unpeened metal. The compressive residual stress made an impact on tension and compression of the plasticity deformation in fatigue crack plasticity zone. That is. the constrained force about plasticity deformation was strengthened by resultant stress, which resulted from plasticity deformation and compressive residual stress in the process of fatigue crack propagation.

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Prediction of the Residual Stress for a Steel Plate after Roller Leveling - Part II : Integrated Model with Accelerated Cooling Model (롤러 레벨링 공정시 후판의 잔류응력 예측 - Part II : 가속냉각 모델을 통합한 모델)

  • Ye, H.S.;Hwang, S.M.
    • Transactions of Materials Processing
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    • v.22 no.1
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    • pp.11-16
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    • 2013
  • Despite its importance the control of roller leveling has primarily relied on the operator's experience and on operation tables. In order to effectively eliminate various shape defects, the optimal leveling condition for a specific mode of plate deformation needs to be determined as well as a careful evaluation as to whether or not the condition is still appropriate for other modes or not. A numerical model, which considers both computation efficiency and accuracy, has been developed. The variations of residual stress are studied according to the entry and the delivery intermeshes, respectively. The camber deformation decreases linearly as the entry intermesh increases. In contrast the curl deformation does not vary directly with the entry intermesh. Therefore, the optimum intermesh values need to be determined in order to simultaneously minimize both the camber and the curl deformation.

Behavior of Geosynthetic Reinforced Modular Block Walls under Sustained Loading (지속하중 재하시 보강토 옹벽의 거동특성 - 축소모형실험)

  • Yoo, Chung-Sik;Kim, Sun-Bin;Byun, Jo-Seph;Kim, Young-Hoon;Han, Dae-Hui
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.121-130
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    • 2006
  • Despite a number of advantages of reinforced earth walls over conventional concrete retaining walls, there exit concerns over long-term residual deformation when used as part of permanent structures. In view of these concerns, time-dependant deformation characteristics of geosynthetic reinforced modular block walls under sustained loads were investigated using reduced-scale model tests. The results indicated that a sustained load can yield appreciable magnitude of residual deformation, and that the magnitude of residual deformation depends on the loading characteristic as well as reinforcement stiffness.

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A study on the warpage and post-deformation in heat resistance test of automotive plastic components (자동차 플라스틱 부품의 내열변형 예측에 관한 연구)

  • Kim, H.Y.;Kim, J.J.;Kim, J.S.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.5
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    • pp.44-52
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    • 1996
  • A procedure predicting warpage and post-deformation due to heat resistance test is presented. The procedure is applied to the injection molding processes of automotive plastic components, which are the door trim and the instrument pannel. The warpage of products is obtained from the residual stress after filling, packing and cooling process, and the post deformation due to the heat resistance test is calculated in the structural analysis of the product at the ejection temperature with the initial condition of residual stress, the boundary conditions and heat resistance conditions. The analyses give some useful guide lines in the design of automotive plastic parts which should satisfy heat resistance regulation.

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