Distortion Analysis of Welded Stiffeners

2001 ◽  
Vol 17 (04) ◽  
pp. 226-240 ◽  
Author(s):  
O. A. Vanli ◽  
P. Michaleris
Keyword(s):  
Residual Stress ◽  
Heat Input ◽  
Welding Process ◽  
Angular Distortion ◽  
Welding Distortion ◽  
Two Dimensional ◽  
Buckling Mode ◽  
Buckling Stress ◽  
Distortion Analysis ◽  
Process Simulations

This paper presents a welding distortion analysis approach for T-stiffeners with a particular emphasis on welding-induced buckling instabilities. Two-dimensional thermomechanical welding process simulations are performed to determine the residual stress and angular distortion. This critical buckling stress along with the buckling mode and bowing distortion are computed in 3-D eigenvalue and linear stress analyses. The effects of the stiffener geometry, weld sequence, weld heat input and mechanical fixturing on the occurrence of buckling and the distortion pattern are investigated.

Experimental Verification of Distortion Analysis of Welded Stiffeners

2002 ◽  
Vol 18 (04) ◽  
pp. 216-225
Author(s):  
M. V. Deo ◽  
P. Michaleris
Keyword(s):  
Experimental Verification ◽  
Experimental Validation ◽  
Welding Process ◽  
Computational Results ◽  
Buckling Mode ◽  
Fea Model ◽  
Buckling Stress ◽  
Distortion Analysis ◽  
Process Simulations ◽  
Buckling Distortion

This paper presents an experimental verification for the predictive distortion analysis approach proposed in Michaleris & DeBicarri (1996,1997) and Vanli & Michaleris (2001) for welded T-type stiffeners. The predictive technique employing the decoupled 2-D and 3-D approach is used for the prediction of buckling distortion and the magnitude of bowing distortion. Two-dimensional thermo-mechanical welding process simulations are performed to determine the residual stress. The critical buckling stress along with the buckling mode are computed in 3-D eigenvalue analyses. Large deformation analyses are carried out to predict the magnitude of bowing distortion. Experimental validation of the prediction is carried out in the lab. Welding experiments are carried out using welding conditions identical to those used in the FEA model. The computational results are then verified with experimental observations

scholarly journals Effect of Trailing Intensive Cooling on Residual Stress and Welding Distortion of Friction Stir Welded 2060 Al-Li Alloy

2018 ◽  
Vol 37 (5) ◽  
pp. 397-403 ◽  
Author(s):  
Shude Ji ◽  
Zhanpeng Yang ◽  
Quan Wen ◽  
Yumei Yue ◽  
Liguo Zhang
Keyword(s):  
Residual Stress ◽  
Friction Stir Welding ◽  
Plastic Strain ◽  
Welding Process ◽  
Butt Joint ◽  
Welding Distortion ◽  
Welding Temperature ◽  
Friction Stir ◽  
Numerical Simulation Methods ◽  
Conventional Cooling

AbstractTrailing intensive cooling with liquid nitrogen has successfully applied to friction stir welding of 2 mm thick 2060 Al-Li alloy. Welding temperature, plastic strain, residual stress and distortion of 2060 Al-Li alloy butt-joint are compared and discussed between conventional cooling and trailing intensive cooling using experimental and numerical simulation methods. The results reveal that trailing intensive cooling is beneficial to shrink high temperature area, reduce peak temperature and decrease plastic strain during friction stir welding process. In addition, the reduction degree of plastic strain outside weld is smaller than that inside weld. Welding distortion presents an anti-saddle shape. Compared with conventional cooling, the reductions of welding distortion and longitudinal residual stresses of welding joint under intense cooling reach 47.7 % and 23.8 %, respectively.

scholarly journals Modified Equivalent Load Method for Welding Distortion Analysis

2020 ◽  
Vol 8 (10) ◽  
pp. 794
Author(s):  
Jaemin Lee ◽  
Hyun Chung
Keyword(s):  
Shell Element ◽  
Angular Distortion ◽  
Computational Time ◽  
Welding Distortion ◽  
Distortion Analysis ◽  
Equivalent Load Method ◽  
Inherent Deformation ◽  
Longitudinal Bending ◽  
Equivalent Load ◽  
Improved Accuracy

In this study, modified equivalent load method for welding distortion analysis is suggested to improve its accuracy. To avoid the excessive computational time for welding distortion analysis of large welded structures, shell element-based elastic analysis methods are widely used, applying the inherent deformation approach. Equivalent nodal forces are commonly used in common FE (Finite Element) codes to enter these inherent deformation values. However, the conventional method cannot estimate precise longitudinal bending following the conventional equation. In this study, the problem of the existing equivalent load method is analyzed by a case study, and the modified equivalent load method that can estimate angular distortion, transverse shrinkage, and longitudinal bending is presented based on the FEM principle. The results show that by applying the proposed method, the shell element-based elastic FE approach for the welding distortion analysis can be achieved with improved accuracy.

Effect of Plate Thickness and Weld Position on Distortion and Residual Stress of Welded Structural Steel

2011 ◽  
Vol 689 ◽  
pp. 296-301 ◽  
Author(s):  
Muhammad Anis ◽  
Winarto
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Structural Steel ◽  
Plate Thickness ◽  
Welding Process ◽  
Diffraction Method ◽  
Longitudinal Direction ◽  
Major Effect ◽  
Angular Distortion ◽  
Vertical Position

Residual stresses are generated as a result of non-uniform temperature distribution during welding and particularly cooling process during fabrication of the welded parts. Residual stresses have a major effect on the overall performance of a component in service. In this instant, the residual stress in the form of angular distortion is primarily caused by shrinkage on longitudinal and transversal direction. Several single v-butt joints on structural steel plates of SS400 are investigated by using different plate thickness and welding positions (1G and 3G). GMAW method was used in the welding process. Measurement of residual stress was carried out on a plate with the thickness of 16 mm on longitudinal, transversal and normal direction by using neutron diffraction method. Results showed that the angular distortion of the welded plates increase with the increase of plate thickness. Welding by vertical position (3G position) resulted in a bigger angular distortion compared to flat position (1G position). The distribution of residual stress varied between tension and compression residual stress along welded area with the range of -10 mm to 10 mm. Measurement of residual stress on the longitudinal direction has the greatest value among two other directions.

Angular Distortion Reduction by In-Process Control Welding Using Back Heating Source

2008 ◽  
Vol 580-582 ◽  
pp. 585-588 ◽  
Author(s):  
Shigetaka Okano ◽  
Masahito Mochizuki ◽  
Masao Toyoda
Keyword(s):  
Process Control ◽  
Heat Source ◽  
Heat Input ◽  
Angular Distortion ◽  
Welding Distortion ◽  
Manufacturing Cost ◽  
Heat Sources ◽  
Heating Method ◽  
Heating Source ◽  
Proper Condition

In order to reduce the number of fabricating processes, it is preferable to control welding distortion during welding; instead of using restraints before the process, or correcting the distortion after the process. The benefits of eliminating extra processes include the reduction of the time and manufacturing cost. This paper presents a method of back heating and welding in tandem, with the back heating occurring at a constant distance from the welding torch during welding. Traditionally, the back heating method has reduced angular distortion in two different ways; One is to bend the welded material in the opposite direction, and the other is homogenization of temperature distribution along the thickness. But, it has recently become known that the angular distortion produced by multiple heat sources, in tandem placement, is not always predicted by the total heat input to the welded joint; and it is possible for the distortion to differ greatly due to factors such as the distance between two heat sources, heat input parameters, and the heat input ratio. Based on these findings, angular distortion is expected to be reduced more effectively by choosing the proper condition for the heat source arrangement in back heating. In this paper, reduction of angular distortion by in-process control welding, using a back heating source, is numerically analyzed by the three-dimensional thermal elastic-plastic analysis, considering moving heat source with weld metal deposition. It was confirmed that the back heating method is effective in reducing angular distortion without restraint or correction. Proper condition concerning the heat source arrangement can be chosen and angular distortion can be perfectly controlled by back heating with ten percent of the welding heat input.

Numerical Modelling of Residual Stress and Distortion in Welded Thin Steel Plates

2008 ◽  
Author(s):  
M. Tsunori ◽  
C. M. Davies ◽  
D. Dye ◽  
K. M. Nikbin
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Welding Process ◽  
Steel Plates ◽  
Thin Plates ◽  
Welding Distortion ◽  
Butt Welding ◽  
Thin Steel ◽  
Out Of Plane ◽  
Plate Size

Current trends in ship design are to reduce panel thickness in order to minimise the vessels weight and hence maximise speed. These panels are manufactured through butt welding thin steel plates with the addition of fillet welded stiffeners. Excessive distortions are exhibited in these thin plates due to the welding process, resulting in major rectification or re-manufacturing costs. The aim of this study is to develop a tool to predict welding residual stresses and distortions in order to understand their governing factors, and thus enabling the optimum fabrication processes to be realized to minimise welding distortion. Finite element simulations are performed of the butt and fillet welding process in 4 mm thick plates of ferritic DH-36 steel and the residual stresses and distortions are predicted. Thermal and residual stress profiles are verified against experimental measurements. The effects of plate and stiffener dimensions are examined numerically. In addition, a sensitivity analysis has been carried out to quantify the effects of restraint on a small butt welded plate. It is concluded that final distortion may be severely reduced, in the plate size considered, if only an out-of-plane constraint is imposed on the plate’s surfaces. Further welding experiments are required to validate these findings.

Weld Distortion Control During Welding Process With Reverse-Side Heating

2006 ◽  
Vol 129 (2) ◽  
pp. 265-270 ◽  
Author(s):  
Masahito Mochizuki ◽  
Masao Toyoda
Keyword(s):  
Weld Line ◽  
Welding Process ◽  
Inert Gas ◽  
Angular Distortion ◽  
Welding Distortion ◽  
Element Analysis ◽  
Distortion Control ◽  
The Finite Element Analysis ◽  
Weld Distortion ◽  
Main Effects

An in-process method for controlling welding distortion in fillet welds is developed. It particularly reduces angular distortion by performing reverse-side Tungsten inert gas (TIG) heating of the weld line at a fixed distance ahead of metal inert gas (MIG) welding during the weld process. Various heating conditions are examined by experiment and by the finite-element analysis in order to determine appropriate conditions and to study the mechanism by which welding distortion is reduced. It is consequently found that this mechanism is a result of two main effects: TIG heating effect on the reverse side, which produces the opposite angular distortion, and preheating effect.

Numerical investigation on the effect of welding speed and heat input on the residual stress of multi-pass TIG welded stainless steel pipe

2020 ◽  
pp. 095440542098133
Author(s):  
Parviz Asadi ◽  
Samaneh Alimohammadi ◽  
Omid Kohantorabi ◽  
Ali Soleymani ◽  
Ali Fazli
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Numerical Investigation ◽  
Welding Speed ◽  
Heat Input ◽  
Three Dimensional ◽  
Welding Process ◽  
Element Model ◽  
Stress States ◽  
Three Dimensional Finite Element

A numerical investigation is provided to study the residual stress states in multi-pass TIG welding of stainless steel SUS304 pipe. An uncoupled thermomechanical three-dimensional finite element model is developed using the ABAQUS software for a circular weld design around the pipe. The effects of weld pass numbers, electrode moving speed, and heat input on the internal and external surface tensions of the pipe are investigated. The simulation results show that by increasing the welding speed, the axial tensile stresses decrease on the pipe surfaces. In the case of hoop stress, as the welding speed raises, the tensile and compressive stresses are increased for both two- and three-pass welding. However, the width of the stress zone becomes narrower in higher welding speeds. The hoop stresses, in comparison with the axial stresses, are more strongly influenced by the welding speed and the heat input. Furthermore, using the three-pass welding process results in much lower stresses in comparison with the two-pass one.

On the effect of heat input in plasma microwelding of maraging steel

2017 ◽  
Vol 233 (3) ◽  
pp. 807-822
Author(s):  
Tinku Saikia ◽  
Mayuri Baruah ◽  
Swarup Bag
Keyword(s):  
Finite Element ◽  
Maraging Steel ◽  
Process Parameters ◽  
Weld Joint ◽  
Heat Input ◽  
Process Model ◽  
Welding Process ◽  
Fusion Welding ◽  
Welding Distortion ◽  
Influence Of Process Parameters

Maraging steel in known as ultra-high strength and toughness material widely used in aerospace industry and defense system. The joining of this material by fusion welding process experiences gigantic metallurgical transformation that have significant contribution toward the development of welding distortion, and transformation of austenite into martensite at very low temperature with significant increase in specific volume. In this study, a set of bead-on-plate welding is executed at microscale to establish feasible range of process parameters using plasma arc as a source of heat. Although, high-concentrated heat does not produce much distortion, the heat input to the weld joint experiences the difference in possible distortion. A finite element–based numerical process model is also developed to investigate the differential influence of process parameters on thermo-mechanical behavior of weld joint. An inverse approach is followed to estimate the unknown input parameters by integrating the finite element model with optimization algorithm. The integrated model predicts the shape and size of weld geometry and welding distortion that are well agreed with experimental values.

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