• Title/Summary/Keyword: 용접지단

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Prevention of Fatigue Failure at Root Region in the Fillet Welded Joint of Steel Bridge (강교량 필렛용접이음부의 루트부 피로파괴 방지)

  • Lim, Cheong Kweon;Park, Moon Ho
    • Journal of Korean Society of Steel Construction
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    • v.12 no.3 s.46
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    • pp.231-238
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    • 2000
  • There was extreme improvement in the processing result of weld toe, but there is possibility that the fatigue failure occurs from the weld root part where the fatigue strength became low relatively. This study did the fatigue test at the cross rib specimens which implemented a partial penetration weld to improve the fatigue strength of the weld root part. As a result of the fatigue test of the partial penetration weld and the fillet weld specimens, almost the same fatigue strength appeared. Because the fatigue failure began from toe, there was not a reinforcement effect in the weld root part by the partial penetration weld. So, it examined fatigue strength at the partial penetration welding specimens which processed toe to stop the fatigue failure of toe part. As a result, there was big fatigue strength improvement from the partial penetration weld than the fillet weld. Therefore, if fatigue crack occurrence can be restrained from toe, it thinks that the fatigue strength of the root part can improve by the partial penetration weld, after all, it thinks that the overall fatigue life can improve.

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The Fatigue Strength of Steel Bridge Components Attached with Non-load Carrying Out-of Plane Gusset Plate (하중 비전달형 면외 거셋판이 부착된 강교량 부재의 피로강도)

  • Woo, Sang Ik;Jung, Kyoung Sup
    • Journal of Korean Society of Steel Construction
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    • v.10 no.4 s.37
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    • pp.779-788
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    • 1998
  • This paper presents the results of the experimental and analytical investigation for the fatigue strength of welded details frequently used in steel bridges, especially for the details with relatively lower fatigue strength. Considering the measured stress fatigue cracking initiated at toe of the transverse fillet weld joining the gusset plates to the web because of the stress concentration that developed as a result of the geometric conditions and the greater probability of microscopic discontinuities at the fillet weld toe A comparison was made of the stress calculated by considering geometric aspect of bead and measured at same position. They indicate that the geometric conditions of the weld toe result in similar stress concentration on both FEM models and test results. The test results were compared with the fatigue criteria of AASHTO, JSSC specifications. Specimens of 80 and 150mm gusset plate configuration tested either respectively equaled or exceeded the fatigue resistance provided by category D and E of the AASHTO specification. It also satisfied the category F and G of JSSC. Both WG1 and WG3 specimen tend to provide S-N curves with a store near -0.3 less than AASHTO and JSSC.

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An Effect of TIG Dressing on Fatigue Characteristics of Non Load-Carrying Fillet Welded Joints (TIG처리에 따른 하중비전달형 필렛용접부의 피로특성)

  • Jung, Young Hwa;Kyung, Kab Soo;Hong, Sung Wook;Kim, Ik Gyeom;Nam, Wang Hyone
    • Journal of Korean Society of Steel Construction
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    • v.12 no.5 s.48
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    • pp.617-628
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    • 2000
  • In this study, the 4-point bending test has been performed in order to estimate the effect of TIG-dressing on fatigue strength and fatigue characteristics quantitatively for non load-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strength of as-welded specimens has been satisfied the grade of fatigue strength prescribed in specifications of domestics and AASHTO & JSSC, and fatigue strength at $2{\times}106cycles$ of TIG-dressing specimens has been increased compared with as-welded specimens. As the result of beachmark tests, fatigue cracks have been occurred at several points, where the radius of curvature and flank angle in the weld bead toes are low, and grown as semi-elliptical cracks, then approached to fracture. As a result of finite element analysis, stress concentration factor in weld bead toes has been closely related to the flank angel and radius of curvature, and between these, the radius of curvature has more largely affected in stress concentration factor than flank angle. As a result of fracture mechanics approaches, the crack correction factor of test specimens has been largely affected on stress gradient correction factor in case a/t is below 0.4. From the relations between stress intensity factor range estimated from FEM analysis and fatigue crack growth rate, fatigue life has been correctly calculated.

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대차 프레임용 SM490A 용접재의 피로 시험

  • 박재실;석창성;구재민;배봉국;김대진;신재호;구병춘
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.05a
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    • pp.87-87
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    • 2004
  • 최근 철도 차량은 안전성, 정시성, 대량 수송성이 우수하여 수송수요가 증가하고 있으며, 열차운행 횟수의 증가와 차량의 고속화로 운행조건이 가혹해짐에 따라 이에 대한 절대적인 안전성과 높은 신뢰성이 요구되고 있다. 철도차량과 같이 반복하중이 연속적으로 작용하는 구조물의 설계에 있어서는 구조물의 사용 환경이나 재료의 피로특성을 최우선의 고려사항으로 간주해야 한다. 실제로 철도차량의 대차 프레임은 맞대기 용접으로 제작되어 있으며, 용접부에서 파손이 발생하고 있다.(중략)

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Effect of Blast Cleaning on Fatigue Behavior of Non-load-carrying Fillet Welded Cruciform Joints (블라스트 표면처리가 하중비전달형 십자필렛 용접이음의 피로거동에 미치는 영향)

  • Kim, In Tae;Jung, Young Soo;Kim, Kwang Jin;Lee, Dong Uk
    • Journal of Korean Society of Steel Construction
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    • v.21 no.1
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    • pp.55-62
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    • 2009
  • Blast cleaning has been applied in steel bridges for cleaning forged surface and increasing adhesive property of applied coating systems. Blasting is the operation of cleaning or preparing a surface by forcible propelling a stream of abrasive metals against it. Blast cleaning may improve surface geometry and induce compressive residual stress, and eventually may increase fatigue life of weld joints. In this paper, fatigue tests were carried out on three types of non-load-carrying fillet welded cruciform joints, as-welded joints, blast-treated joints, and stress-relieved joints after blasting, in order to investigate effect of blast cleaning on fatigue behavior of the weld joints. By Blast cleaning, the weld toe radius was increased by 29% and compressive residual stress was induced near weld toes. Blast cleaning increased fatigue life and fatigue endurance limit of the weld joints. When the applied stress ranges decreased, the increment in fatigue life became larger. About a 150% increase in fatigue limit could be realized by using blast cleaning.

Fatigue Characteristics of Non Load-Carrying Fillet Welded Joints according to Post-Processing in Weld Bead Toes (용접지단부의 후처리에 따른 하중비전달형 필렛용접부의 피로특성)

  • Hong, Sung Wook;Kyung, Kab Soo;Choi, Dong-Ho;Yong, Hwan Sun
    • Journal of Korean Society of Steel Construction
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    • v.12 no.6
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    • pp.701-713
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    • 2000
  • In this study, the 4-point bending test been performed in order to estimate effect of grinding on fatigue characteristics quantitatively for as-welded specimen, grinding specimen & TIG-dressing specimen for non load-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strength at $2{\times}106$cycles of grinding specimen and TIG-dressing specimen has been increased compared with as-welded specimen and satisfied the grade of fatigue strength prescribed in specifications of domestics and AASHTO & JSSC. As a result of beachmark test, fatigue cracks on all specimens have occurred at several points where stress

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Fatigue Analysis of Welded Toe of Wind Turbine Tower Access Door (Wind Turbine Tower의 Door 용접부에 대한 피로 강도 연구)

  • Han Dong-Young;Koh Jang-Wook;Choi Won-Ho;Lee Seung-Kuh
    • 한국신재생에너지학회:학술대회논문집
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    • 2005.06a
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    • pp.72-75
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    • 2005
  • Recently, as the global warming by fossil fuels become social issues. the interest of renewable energy producing system is increasing rapidly. Among these, wind turbines are most highlighted because of its economic competitiveness. The tower occupying about $20\%$ of overall turbine costs, is one of the main components of wind turbine. Tower access door located to base part of the tower, is used to enter the tower. This is the main structural weak point because of door hole, weldment, etc. In this study, by FEM, we retrieved the maximum van Mises stress at door location and carried out fatigue analysis using stresses at weld toe locations of tower access door part.

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Fatigue Characteristics of SM490A Welded Joints for Bogie Frame (대차 프레임용 SM490A 용접재의 피로 특성 평가)

  • Park Jae Sil;Seok Chang Sung;Koo Jae Mean;Shin Jae Ho;Goo Byeong Choon
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.12
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    • pp.146-153
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    • 2004
  • We compared the fatigue characteristics of weld metal with those of base metal, and not heat-treated with heat-treated. Also, we examined the influence of bead in a viewpoint of fatigue life. From the experimental results, it has been seen that the fatigue characteristics of welded specimens grinded the toe of bead are slightly better than not grinded. We have seen that the fatigue life is affected more by the stress concentration on the profile change in the weld toe rather than by residual stress influence, because heat-treated or not had almost no influence on the fatigue characteristics.

The study for strength of welds of the wind turbine tower (풍력 발전 시스템 타워의 용접부 강도 연구)

  • Han, Dong-Young;Ahn, Kyung-Min;Choi, Won-Ho;Lee, Seung-Kuh
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.06a
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    • pp.304-307
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    • 2006
  • Recently, as the global warming by fossil fuels and the steep rise of the oil price become social issues, the interest for renewable energy producing system is increasing rapidly. Among these, the wind turbine is most highlighted because of its economic competitiveness. The tower is one of the main components of wind turbine, which occupying about 20% of overall turbine costs. The tower access door located to base part of the tower, is used to enter the tower. This is the main structural weak points because of door hole, weldment, etc. And so are the weldments between the cans and the flanges. In this study, for the top flange part of the tower, by FEM using ANSYS, we retrieved the maximum von Mises stress on that and carried out fatigue analysis using stresses at such weak points.

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The Effect of Blast Cleaning for Steel Bridge Painting on Fatigue Behavior of Out-of-Plane Gusset Welded Joints (강교 도장용 블라스트 처리가 면외거셋 용접이음의 피로거동에 미치는 영향)

  • Kim, In Tae;Le, Van Phuoc Nhan;Kim, Kwang Jin;Lee, Dong Uk
    • Journal of Korean Society of Steel Construction
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    • v.20 no.5
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    • pp.583-590
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    • 2008
  • Blasting has been applied in newly-built steel structures for cleaning forged surfaces and increasing the adhesive property of applied painting systems. However, the effect of the blast cleaning on fatigue behavior of welded joints is not clear. In this paper, fatigue tests were carried out on out-of-plane gusset welded joints and the effect of the blast cleaning on the fatigue behavior was studied. The curvature radius at the weld toe of the surface-treated specimens by using the blast method is larger than that of as-welded specimens. By the blast cleaning compressive residual stresses were induced into weld toes. The experimental results showed that the fatigue life of surface-treated specimens is longer than that of as-welded specimens, even though the fatigue life of surface-treated specimens and that of as-welded specimens are not clearly different in the high stress range. About a 160% increase in fatigue limit could be realized by using blast cleaning.