• Title/Summary/Keyword: Welded

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Application of the Backward Tracing Scheme of Finite Element Method to Tailored Blank Design and Welding Line Movement in Sheet Metal Forming (두께가 다른 두 용접판재 성형에 있어서 블랭크 설계 및 용접선 이동에 대한 유한요소법의 역추적기법 적용)

  • 구태완;최한호;강범수
    • Transactions of Materials Processing
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    • v.9 no.5
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    • pp.453-462
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    • 2000
  • Tailor-welded blanks are used for forming of automobile structural skin components. The main objective of this study is to achieve weight and cost reduction in manufacturing of components. For successful application of tailor-welded blanks, design of initial welded blanks and prediction of the welding line movement are critical. The utilization of the backward tracing scheme of the finite element method shows to be desirable in design of initial welded blanks for net-shape production and in prediction of the welding line movement. First the design of the initial blank in forming of welded thick sheet with isotropy is tried, and it appears successful in obtaining a net-shape stamping product. Based on the first trial approach, the backward tracing scheme is applied to anisotropic tailored blanks. The welding line movement is also discussed.

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Forming Characteristics of Laser Welded Tailored Blanks III : Stretch Forming Characteristics (레이저 용접 테일러드 블랭크의 기본 성형특성 III : 신장성형 특성)

  • Park, Gi-Cheol;Han, Su-Sik;Jin, Jo-Gwan;Gwon, O-Jun
    • Transactions of Materials Processing
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    • v.7 no.4
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    • pp.354-363
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    • 1998
  • In order to analyze the stretch forming characteristics of tailored blanks, laser welded blanks of different thickness and strength combinations were prepared and stretching tests were done. The stretching formability of laser welded blanks was reduced as increasing the deformation restraining force ($strength{\times}thickness$) ratio between two welded sheets. Weld line movement was attributed to strain concentration at weaker sheets and resulted in fracture at weaker sid, so that fracture could be predicted by the forming limit of the weak sheet. In the case of a welded blank with the similar deformation restraining force rations between two welded sheets, crack occurred at weld and its forming limit was about 15% less than the base sheet. The effects of lubrication and weld line position on stretch-ing formability were also investigated by experiments. Lower friction did not always give better formability for tailored blanks. Stretching formability was observed to be improved as increasing the area of weak sheet.

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Stress Comparison on Welded Connection between Detail FE Model and Classical Calculation (계산 방법론에 따른 용접부 응력 평가 및 비교(FE 상세 모델 vs 수 계산))

  • Song, Moon-Sung;Jeong, Sang-Woong
    • Proceedings of the KSR Conference
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    • 2010.06a
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    • pp.621-626
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    • 2010
  • According to development of method and device of Finite Element Analysis, the strength of welded joint is demonstrated by Finite Element Analysis not classical calculations. On the FEA, all of the joints for carbody are assumed to be ideal connections and the yield stress of welded joint is assumed to be the same to base metal. On these assumption, FEA is appropriate to evaluate the overall stability and strength of whole carbody. The classical calculation is appropriate to evaluate strength of specific welded joint and to determine the weld method and properties. Some project request strength calculation of the specific welded joints in addition to FEA, because of the demonstration of stability. The objective of this paper is the check of the consistency of the FEA result for the welded joints by the stress comparison between Detailed FE Model and classical calculation and the evaluation of the reliability of FEA result.

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Experimental Study on Hardness and Wear Characteristics of Welded Rails (레일 용접부의 경도와 마멸특성에 관한 실험적 연구)

  • 김청균;황준태;나성훈;민경주
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.10a
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    • pp.234-243
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    • 1998
  • In this paper, thermite and gas pressure weldings have been used to join rails in-track and analyzed as functions of hardness and wear characteristics. The wear rate of thermite welded rail is low compared with that of gas pressure welded rail, which is tested in a pin-on-disk wear tester. The hardness of thermite welded materials is relatively high and narrow distributed between three zones, welded part, thermally affected zone, and a base matrix. Wear of a welded rail may be a major factor in railroad maintenance costs and failures at the rail-rail butt joint.

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Strength and Ductility of R/C Columns with Welded Reinforcement Grids(II) - Focused on Comparisons with Columns Confined by Conventional Reinforcement (용접 띠철근으로 보강된 철근콘크리트 기둥의 강도와 연성(II) - 보편적인 띠철근 보강 기둥과의 비교를 중심으로)

  • ;Murat Saatcioglu;Mongi Grira
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.10a
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    • pp.561-568
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    • 1997
  • Conventional confinement reinforcement for rectangular columns consist of closely spaced perimeter hoops, overlapping hoops, and crossties. One of the potential alternatives to conventional reinforcement is a welded reinforcement grid, prefabricated to required size and volumetric ratio of transverse reinforcement. An experimental investigation was carried out to investigate the strength and deformability of reinforced concrete columns confined with welded reinforcement grids. The comparisons of the envelopes of experimental force-displacement hysteric relationships for columns confined by welded grids with analytically generated force-displacement curves for columns confined with conventional ties. In general, inelastic deformability beyond the peak, as indicate by the slope of the cuvers, was similar to those indicated by columns with conventional ties. The superior performance of columns with welded grids may be attributed to the improved confinement characteristics of grids associated with increased rigidity of welded ties.

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The effect of welding methods on the stress corrosion behavior of the welded austenitic stainless steel (오스테나이트 스테인리스강 용접부의 응력부식 거동에 미치는 용접 방법의 영향)

  • 백신영
    • Journal of Advanced Marine Engineering and Technology
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    • v.19 no.4
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    • pp.42-50
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    • 1995
  • To study the effect of welding methods on the Stress Corrosion Cracking (SCC) behavior of welded AISI type 316L and 304 austenitic stainless steel, the Slow Strain Rate Technique(SSRT) has been adopted in the boiling 45 wt% $MgCl_2$ solution. The results are as follows. 1) Welded sections are more susceptible than base metal in SCC, and the rank of SCC, and the rasistance in welding method is TIG, MIG, $CO_2$ and ARC. 2) The Ultimate tensile strength(UTS) and the strain of both base metal and welded joint are reduced as decreasing extension rate. 3) The SCC resistance of 316L base metal and welded sections are superior than that of 304. 4) The tendency of pitting and the SCC suseptibility are agreed well, and the SCC site is welded deposit section in 316L whereas HAZ in 304.

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A Study on Fatigue Design for Welded Joint of STS301L (STS301L 용접종류별 이음재의 피로설계에 관한 연구)

  • Baek, Seung-Yeb
    • Journal of Welding and Joining
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    • v.28 no.3
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    • pp.86-91
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    • 2010
  • Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. For fatigue design of gas welded joints such as fillet and plug type joint, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. And also, the influence of the geometrical parameters of gas welded joints on stress distribution and fatigue strength must be evaluated. the ${\Delta}P-N_f$ curves were obtained by fatigue tests. Using these results, ${\Delta}P-N_f$ curves were rearranged in the ${\Delta}{\sigma}-N_f$ relation with the maximum stress at the edge of fillet welded joint.

A Study on Fatigue Design of CT-Type Spot Welded Lap Joint (CT형 점용접 이음재의 피로설계에 관한 연구)

  • Baek, Seung-Yeb
    • Journal of Welding and Joining
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    • v.28 no.2
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    • pp.91-95
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    • 2010
  • Stress distribution and deformation on the CT-type(Cross Tension type) spot welded lap joint subjected to out of plane tensile load were investigated by finite element method. Using the maximum principal stresses at the nugget edge obtained by FEM analysis, evaluated the fatigue strength of the CT-type spot welded lap joints having various dimensions and materials. and also, the influence of the geometrical parameters of CT-type spot welded lap joints on stress distribution and fatigue strength must be evaluated. thus, in this paper, ${\Delta}P-N_f$ curve were obtained by fatigue tests. Using these results, ${\Delta}P-N_f$ curve were systematically rearranged in the $\Delta\sigma-N_f$ relation with the hot spot stresses at the CT-type spot welded lab joints. It was found that the proposed $\Delta\sigma-N_f$ relation could provide a more reasonable fatigue design criterion for the CT-type spot welded lap joints.

Design of Weld Line of a Tailor Welded Blank by Inverse Finite Element Analysis (유한요소 역해석을 이용한 Tailor Welded Blank의 용접선 설계)

  • Lee, Choong-Ho;Huh, Hoon;Han, Soo-Sik
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1997.10a
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    • pp.89-92
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    • 1997
  • Design of a weld line in a tailor welded blank is indispensable for good manufacturing of stamped parts as assigned, since the intial weld line is distorted severely with forming. The initial weld line has to be determined such that desired weld line in a formed part can be obtained. The initial weld line was predicted by inverse finite element analysis from the desired weld line in a formed part. The inverse approach is applied to the cylindrical and square cup drawing with tailor welded blanks. The applications demonstrates that the approach is useful for design of weld line of tailor welded blank.

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Fatigue Strength Evaluation on the IB-Type Spot Welded Lap Joint of 304 Stainless Steel Part 2 : Strain energy Density (304 스테인레스 박강판 IB형 용접이음재의 피로강도 평가 Part 2 : 변형에너지 밀도에 의한 평가)

  • 손일선;오세빈;배동호
    • Journal of Welding and Joining
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    • v.17 no.6
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    • pp.32-37
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    • 1999
  • Since stainless steel plates have good mechanical properties, weldability, appearance and resistance of corrosion, these are traditionally used for vehicles such as the bus and the train. And they are mainly fabricated by spot welding. But fatigue strength of their spot welded joint is considerably influenced by welding conditions as well as geometrical factors. Thus a reasonable and systematic criterion for long life design of spot welded body structure must be established. In this report, strain energy density was analyzed by using 3-dimensional finite element model about the IB-type spot welded lap joint under tension-shear load. Fatigue tests were conducted on them having various thickness, joint angle, lapped length and width. From their results, it was found that fatigue strength of the IB-type spot welded lap joints could be effectively and systematically rearranged by strain energy density at the edge of nugget.

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