• Title/Summary/Keyword: Welding Residual Stresses Finite Element Method

Search Result 73, Processing Time 0.025 seconds

A Study on the Mechanical Characteristics of the Resistance Multi-spot Welded Joints (저항 다점용접부의 역학적 특성에 관한 연구)

  • 방한서;방희선
    • Journal of Welding and Joining
    • /
    • v.19 no.5
    • /
    • pp.499-505
    • /
    • 2001
  • In order to classify the mechanical phenomena of thermal elasto-plastic behavior on the multi-spot welded joints, this study has tried to carry out three-dimensional thermal elasto-plastic analysis on them. However, because the shape of multi-spot welded joints is not taxi-symmetric, unlike the cafe of single-spot welded joint, the solution domain for simulation should be three dimension. Therefore, in this paper, firstly, the three-dimensional thermal elasto-plastic program is developed by an iso-parametric finite element method. Secondly, from the results analyzed by developed program, this has clarified mechanical characteristics and their production mechanism on single and multi-spot waled joints. Moreover, it has been intended to make clear effects of pitch length on welding residual stresses, plastic strain of multi-spot welded joints.

  • PDF

Effects of Heat Input and Bead Generation Methods on Finite Element Analysis of Cylindrical Multi-Pass Welding Process of Metals (열원 입력과 비드 생성 방법이 원통형 다층 금속 용접 과정의 유한요소해석에 미치는 영향)

  • Park, Won Dong;Bahn, Chi Bum;Kim, Ji Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.41 no.6
    • /
    • pp.455-467
    • /
    • 2017
  • In this study, a finite element analysis of a cylindrical multi-pass weldment for dissimilar metals was performed. The effects of the heat input method and weld bead generation method were considered. We compared two heat input methods: the heat flux method and the temperature method. We also compared two weld bead generation methods: the element birth method and the quiet element method. Although the results of the thermal analysis show deviations between the two heat input methods, the welding residual stresses were similar. Because the areas exposed to high temperature were similar and the strength of the material was very low in high temperature (above the $1000^{\circ}C$), the effects of the weld bead temperature were insignificant. The distributions of the welding residual stress were similar to each other. However, gaps and overlaps occurred on the welding boundary surfaces when the element birth method was applied. The quiet element method is more suitable for a large deformation model in order to simulate a more accurate weld shape.

The Plane-Deformation Thermal Elasto-Plastic Analysis During Welding of Plate (평판용접에 관한 평면변형 열탄소성 해석)

  • 방한서;한길영
    • Journal of Ocean Engineering and Technology
    • /
    • v.8 no.1
    • /
    • pp.33-40
    • /
    • 1994
  • Welding of structure produces welding residual stresses which influence buckling strength, brittle fracture strength and cold crack on the weld parts. Therefore, it is very important to accurately analyze the residual stress before welding in order to guarantee the safety of weldment. If the weld length is long enough compared to the thickness and the breadth of plate, thermal and mechanical behaviors in the middle portion of the plate are assumed to be uniform along the thickness direction(z-axis). Thus, the following conditions(so-called plane deformation) can be assumed for the plate except near its end;1) distributions of stress and strain are independent on the z-axis;2) plane normal to z-axis before deformation remains plane during and after deformation. In this paper, plane-deformation thermal elasto-plastic problem is formulated by being based on the finite element method. Moreover special regards and paid to the fact that material properties in elastic and plastic region are temperature-dependence. And the method to solve the plane-deformation thermal elasto-plastic problem is shown by using the incremental technique. From the results of analysis, the characterisics of distribution of welding residual stress and plastic strain with the production mechanism are clarified.

  • PDF

A Study of Heat Flow and Residual Stress Analysis in Pipe-plate Gas Metal Arc Brazing (파이프-평판 GMAB 접합부의 열유동 및 잔류음력 해석에 관한 연구)

  • 이태영;김재웅;이목영;정평석
    • Journal of Welding and Joining
    • /
    • v.19 no.4
    • /
    • pp.413-422
    • /
    • 2001
  • In this study. two-dimensional heat flow and residual stress in arc brazing to join the pipe and plate structure were analyzed by using a commercialized FEM package. Advantages offered by arc brazing are that strong joints can be produced with lower heat input than that of previous gas metal arc welding and narrower heat affected zone can usually be obtained than that in the case of torch brazing. To investigate the effects of process variables and minimize the thermal effects on the structure, this study presents a method for analyzing the heat flow and residual stress in arc brazing process according to variables such as traveling speed, torch angle and position. The simulation results were compared with the experimental ones to verify the numerical analysis method. The experiments include the measurement of HAZ size from the section of joints and residual stresses by using strain gages named 'section method'. A comparatively good agreement between the results of numerical analysis and experimental ones could be obtained in both of the temperature distribution and residual stress of the brazed structure. Using the proposed numerical analysis method, the process parameters were evaluated to get proper arc brazing conditions.

  • PDF

Estimation of Fatigue Strength in Resistance Spot Weldment of the Vehicle Body (차체 저항 점 용접부 피로수명 예측)

  • 손광재;양영수;조성규;장상균
    • Journal of Welding and Joining
    • /
    • v.20 no.2
    • /
    • pp.59-64
    • /
    • 2002
  • When the vehicle travels in an actual road, resistance spot weldments of the vehicle structure are exposed to complex loading state. Since the fatigue strength in resistance spot weldment of vehicle body can be determined by effect of residual stresses and loading state of driving, estimating actual loading state and considering residual stress effect are needed. In this study, Fatigue stress-fatigue life relation concerned residual stress effect was obtained by thermo elastic plastic finite element analysis. And applied loading in resistance spot weldments of vehicle body was calculated by dynamic analysis. Presumption of fatigue life was performed using proposed method

A Study on the Influece of Residual Stresses on Fatigue Crack Growth Behaviors in the Weldment Plate with Various Thickness (변후 용접판재에서의 피로균열성장거동에 미치는 잔류응력의 영향에 관한 파괴역학적 연구)

  • 차용훈
    • Journal of the Korean Society of Safety
    • /
    • v.8 no.1
    • /
    • pp.71-79
    • /
    • 1993
  • The welding implementation used widely in the industrial field is gradually increasing due to weight reduction. unlimited material thickness. simplified structure design. and 1 manufacturing time and cost reduction. The most significant factor that influences the fatigue crack growth rate is the residual stress generated during the welding process. Many researchers have studied the effect of the residual stress on crack growth behavior. Through a fatigue test in a various-thickness welded specimen. redistributed residual stress is measured as the crack is developed. Then. by superposing the measured residual stress on the K value obtained by the finite element method.

  • PDF

Investigation on the Effect of Strength Mismatch on Residual Stresses in Welds with Different Strength Used in Buried Natural Gas Pipeline (매설 가스 배관 이종금속 용접부의 강도 불일치가 잔류응력에 미치는 영향 고찰)

  • Kim, Jong-Sung;Kim, Woo-Sik;Baek, Jong-Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.34 no.4
    • /
    • pp.413-421
    • /
    • 2010
  • In this study, residual-stress distributions in welds with different strength used in natural gas pipelines are calculated by using finite-element analysis and simulating a realistic welding process. The temperature and residual-stress analysis results are compared with the real fusion profile and the application results of the Fitness-For-Service assessment code, API 579 in order to validate the finite-element analysis model and procedure. Parametric study is performed to assess the effect of welding and material variables such as mechanical strength mismatch, the strength of weld metal, reinforcement, and heat input on the residual stress distributions. Finally, on the basis of the parametric study results, the effects of these variables on residual stress distributions are investigated. In particular, the strength mismatch between base metals has an insignificant effect on residual-stress distributions.

Residual Stress Distribution on the Fillet Weldment used by Finite Element Method (유한요소법을 이용한 필렛용접 이음부의 잔류응력분포)

  • Kim, Hyun Sung;Woo, Sang Ik;Jung, Kyoung Sup
    • Journal of Korean Society of Steel Construction
    • /
    • v.12 no.2 s.45
    • /
    • pp.197-207
    • /
    • 2000
  • A transient heat transfer analysis and thermo-elastic analysis have been performed for the residual stress distribution on the fillet weldment used by finite element method. Specimen is fabricated single-pass fillet welding. This computation was performed for conditions including surface heat flux and temperature dependent thermo-physical properties using by heat input as parameter. Also, cut-off temperature of residual stress estimation by thermo-elastic analysis is determined. The fillet weldment were measured to determined their residual stress distributions for using hole-drilling method. As result, it was found that large tensile residual stress is about material yield strength, and the numerical simulation results for finite element method similar to residual stresses by hole-drilling method and other exiting research. Also, cut-off temperature is effectively determined by temperature which calculated maximum thermal stress equal to material yield strength.

  • PDF

An Analysis of Thermal Stress and Angular Distortion in Bead-on-Plate Welding Incorporating Constrained Boundary Conditions (판재의 비드 용접에서 구속경계조건을 적용한 열응력 및 각변형 해석)

  • 배강열;최태완
    • Journal of Welding and Joining
    • /
    • v.17 no.1
    • /
    • pp.104-115
    • /
    • 1999
  • There have been many studies on the two dimensional thermo-elasto-plastic analysis in welding process, mostly from viewpoint of residual stresses. In this study, the temperature distribution, transient thermal stress, and angular distortion during bead-on-plate gas metal arc welding of rectangular plates were analyzed by using the finite element method. A nonlinear heat transfer analysis was first performed by taking account of the temperature-dependent material properties and convection heat losses on the surface. This was followed by a thermo-elasto-plastic stresses and distortion analysis that incorporates the constrained boundary condition of the two dimensional solution domain to get the three dimensional size effect of the plate. The constrained boundary conditions adopted in this study were the constant displacement condition over the whole two dimensional section for axial movement in the welding direction, and the force boundary condition for rotational movementof the domain around the axis of the welding direction. It could be revealed that the theoretical predictions of the angular distortion have an improved agreement with the experimentally obtained data presented in the previous study.

  • PDF

Distribution Characteristics of Weld Residual Stress on Butt Welded Dissimilar Metal Plate (이종금속 평판 맞대기용접의 용접잔류응력 분포특성)

  • Lee, Kyoung-Soo;Park, Chi-Yong;Kim, Maan-Won;Park, Jai-Hak
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.34 no.9
    • /
    • pp.1317-1323
    • /
    • 2010
  • In this study, the weld residual stress distribution at a dissimilar-metal welded plate of low alloy carbon steel and stainless steel, which are widely used in nuclear power plants, was characterized. A plate mock-up with butt welding was fabricated using SA 508 low alloy steel and Type 304 stainless steel plates and the residual stresses were measured by the X-ray diffraction method after electrolytic polishing of the plate specimen. Finite element analysis was carried out in order to simulate the butt welding of dissimilar metal plate, and the calculated weld residual stress distribution was compared with that obtained from the measured data. The characteristics of the three-dimensional residual stress distribution in a butt weld of dissimilar metal plates were investigated by comparing the measured and calculated residual stress data.