• Title/Summary/Keyword: Residual stress distribution

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A Study on the Influence Residual Stresses on Fatigue Crack Growth Behaviors in the Butt Welded Plate (Butt 용접판재에서의 피로균열성장거동에 미치는 잔류응력의 영향에 관한 연구)

  • 차용훈;정종안;채경수;김하식
    • Journal of the Korean Society of Safety
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    • v.8 no.2
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    • pp.64-71
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    • 1993
  • In this study, the purpose is to investigate the influence of initial residual stresses on the fatigue crack growth behaviors after the distribution of initial residual stresses Is measured when the crack is growing from the compressive residual stresses field to the tensile residual stress field. Also, the Influence of the variation of residual stress distribution on the fatigue crack growth behaviors at the crack tip is studied when the initial crack li applied on base metal, weld metal and HAZ respectively.

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A Study of the Development of the Stress Optic Law of Photoelastic Experiment Considering Residual Stress

  • Suh, Jae-guk;Hawong, Jai-sug;Shin, Dong-chul
    • Journal of Mechanical Science and Technology
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    • v.17 no.11
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    • pp.1674-1681
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    • 2003
  • Photoelastic experiment has two significant problems. The first problem is manufacturing a model specimen for complicated shapes of structures. The second problem is residual stress contained in the photoelastic model material. In this paper, the stress optic law that can be effectively used on photoelastic model materials with residual stress is developed. By using the stress optic law as developed in this research, we can obtain good results in photoelastic experiments using model material in which residual stress is contained. It is assured that the stress optic law developed in this research is useful. Therefore, it is suggested that the stress optic law considering residual stress can be applied to the photoelastic experiment for the stress analysis of the composite materials or bi-materials in which the residual stress is easily contained.

Residual Stress Distribution according to Working Conditions in Grinding Operation (연삭가공시 연삭조건에 따른 잔류응력 분포에 관한 연구)

  • Cheong, Chae-Cheon;Cha, Il-Nam;Kim, Gyung-Nyun
    • Journal of the Korean Society for Precision Engineering
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    • v.7 no.4
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    • pp.23-28
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    • 1990
  • This study is to investigate the magnitude, direction and distribution of residual stresses in surface ground plate according to working conditions. The specimens were made of structural carbon steel and were machined in various grinding conditions. These were divided in two groups; heat-treated materials and non-heat-treated materials. In each working condition, let the ground specimen generate displacements using deflection-etching techniques. At the same time, these displacements were precisely measured with electronic micrometer. Through the relation formula between the plane stress and strain, which was derived using these measured data, the values of residual stress are calculated, and the results are analyzed. These results are as follows : 1. According to the working conditions in this experiment, it can be seen that the distribution of residual stress generally had same trend and the maximum residual stress remained in 20~30 ((${\mu}m$) beneath the surface. 2. It is observed that compressive residual stress changes into tensile stress in 5~20 (${\mu}m$) beneath the surface. It is suggested that such phenomenon is originated from the friction effect in grinding process. 3. As the hardness increases by the heat treatment, residual stress increases. 4. As the fatigue strength increases by the compressive residual stress, it is desirable that the dowm feed and table feed reduce. 5. It can be seen that the more great the down feed and table feed increase, the more close the changing point, where the stress changed from compressive to tensile, is colse to the surface. This is due to the resultant effects of the grinding temperature and resistence are larger than the effect of the friction.

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Characterization of residual stress distribution of thick steel weld by contour method (굴곡측정법을 이용한 극후판 용접부 잔류응력분포 정량분석)

  • Kim, Dong-Kyu;Woo, Wanchuck;Kang, Youn-Hee
    • Journal of Welding and Joining
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    • v.33 no.1
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    • pp.24-29
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    • 2015
  • Residual stresses arising from the materials processing such as welding and joining affect significantly the structural integrity depending on the external loading condition. The quantitative measurement of the residual stresses is of great importance in order to characterize the effects of the residual stresses on the structural safety. In this paper, we introduce a newly devised destructive technique, the contour method (CM), which is applied for the measurements of the residual stress distributions through the thickness of a 80 mm thick steel weld. Residual stresses are evaluated from the contour, which is the normal displacement on a cut surface produced by the relaxation of residual stresses, using a finite element model. The CM provides a two-dimensional map of the residual stresses normal to the cut surface. The CM developed in the present study was validated in comparison with the residual stress distribution determined by a well-established neutron-diffraction residual stress instrument (RSI) instrumented in HANARO neutron research reactor.

A Study on the Distribution of Residual Stress for Drilled Shaft (현장타설말뚝의 잔류응력 분포에 관한 연구)

  • Kim, Won-Cheul;Hwang, Young-Cheol;Ahn, Chang-Yoon
    • Journal of the Korean GEO-environmental Society
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    • v.6 no.1
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    • pp.45-51
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    • 2005
  • The distribution of shaft resistance is measured by the static load test with the strain gauge or stress gauge, so that the long-term load distribution must be considered for the pile design. However, the measurement by strain gauge generally assumes the 'zero reading', which is the reading taken at 'zero time' with 'zero' load and the residual stress, which is the negative skin friction(or the negative shaft resistance) caused by the pile construction, is neglected. Therefore, the measured value by strain gauge is different from the true load-distribution because residual stresses were neglected. In this study, the three drilled shafts were constructed, and the strain measurements were carried out just after shaft construction. As a result of this study, it is shown that the true load-distribution of drilled shaft is quite different with known load distribution and the true load-distribution of drilled shaft changed from the negative skin friction to the positive skin according to the load increment.

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Fatigue Strength Evaluation of IB-Type Spot Welded Lap Joint considered Residual Stress (잔류응력을 고려한 IB형 spot 용접이음재의 피로강도 평가)

  • 손일선
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1997.10a
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    • pp.127-131
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    • 1997
  • In systematic and orderly estimation of fatigue strength of the spot welded lap joints, because the influence of residual stress of fatigue crach initiation and growth is not negligible, there need to estimate fatigue strength considered residual stress at near spot weld part of the lap joints. Therefore, in this thesis, peformed stress distribution and residual stress analysis at near the spot weld part by F.E.M and X-ray diffraction method, and obtained the maximum principal stress considered residual stress at nugget edge by superposing residual stress at nugget edge by superposing their results. From the results obtained above, we could find that fatigue strength of the IB-type spot welded lap joints was rearranged by the maximum principal stress considered residual stress at nugget edge and was entirely low about 13 percents compare with that neglected residual stress.

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N.M.for the Effect of P.T. on Resicual Stress Relaxation (잔류응력 완화에 미치는 상변태의 수치적 모델링)

  • 장경복;손금렬;강성수
    • Journal of Welding and Joining
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    • v.17 no.6
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    • pp.84-89
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    • 1999
  • Most of ferrous b.c.c weld materials may experience martensitic transformation during rapid cooling after welding. It is well known that volume expansion due to the phase transformation could influence on the relaxation of welding residual stress. To apply this effect practically, it is a prerequisite to establish a numerical model which is able to estimate the effect of phase transformation on residual stress relaxation quantitatively. For this purpose, the analysis is carried out in two regions. i.e., heating and cooling, because the variation of material properties following a phase transformation in cooling is different in comparison with the case in heating, even at the same temperature. The variation of material properties following phase transformation is considered by the adjustment of specific heat and thermal expansion coefficient, and the distribution of residual stress in analysis is compared with that of experiment by previous study. consequently, in this study, simplified numerical procedures considering phase transformation, which based on a commercial finite element package was established through comparing with the experimental data of residual stress distribution by other researcher. To consider the phase transformation effect on residual stress relaxation, the transition of mechanical and thermal property such as thermal expansion coefficient and specific heat capacity was found by try and error method in this analysis.

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Residual Stress Evolution during Leveling of Hot Rolled Cold Forming Purpose High Strength Coils and Camber Prediction (냉간 성형용 열연 고강도 강판의 교정 중 잔류음력 변화와 절단 후 camber 발생 거동 연구)

  • Park, K.C.;Ryu, J.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.10a
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    • pp.112-115
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    • 2007
  • In order to investigate the residual stress evolution during the leveling process of hot rolled high strength coils for cold forming, the in-plane residual stress of plate sampled at SPM, rough leveler and finish leveler were measured by cutting method. Residual stress was localized near the edge of plate. As the thickness of plate was increased, the region with residual stress was expanded. The gradient of residual stress within plate was reduced during the leveling process. But the residual stress itself was not removed at the ranges of tested conditions. From the measured residual stress distribution within the plate, camber of plate cut to small width was predicted exactly within error range of experiment.

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Analysis of Temperature Distribution and Residual Stress in Deposition Process of Metal Droplet by Using Laser Beam (레이저를 이용한 금속액적 적층시 온도분포와 잔류응력 해석)

  • Yun Jin-Oh;Yang Young-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.3 s.168
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    • pp.187-193
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    • 2005
  • The temperature distribution of the deposited droplet was predicted by using the finite element analysis and it was assumed that the droplet was axisymmetrical model. The analysis of residual stress was performed with the temperature data, which is obtained from the result. Axisymmetric droplet is deposited three times to consider the actual phenomenon of droplet deposition. The analysis of the temperature distribution is respectively performed whenever the axisymmetric droplet is laminated and the residual stresses of the laminated axisymmetric droplet are calculated with the value of the temperature distribution.

Residual Stress Evaluation Caused by Press Forming and Welding of 600MPa Class Circular Steel Tube Using Hole-Drilling Strain Gage Method (홀드릴링 변형 게이지법을 이용한 600MPa급 원형 강관 제작상의 잔류응력평가)

  • Im, Sung Woo;Lee, E.T.;Shim, Hyun Ju;Kim, Jong Won;Chang, In Hwa
    • Journal of Korean Society of Steel Construction
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    • v.18 no.5
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    • pp.625-631
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    • 2006
  • Residual stresses in structural materials are stresses that exist in the objective without the application of any service or other external loads. Manufacturing processes are the most common causes of residual stress. To examine the effect and the distribution of residual stress due to press forming and welding in the production of a 600MPa-class steel tube, a residual stress evaluation test was performed. The measurement used the Hole-Drilling Strain Gauge Method and evaluated the distribution of residual stress, which measured a total of 59 places near the welding line.