Prediction of Residual Stresses and Distortions in Welded Structures

1993 ◽  
Vol 115 (1) ◽  
pp. 52-57 ◽  
Author(s):  
B. L. Josefson
Keyword(s):  
Residual Stresses ◽  
Spot Welding ◽  
Thermal Design ◽  
Welding Residual Stress ◽  
Temperature History ◽  
Residual Stress Field ◽  
Butt Welding ◽  
Box Beams ◽  
Design Loads ◽  
Good Agreement

A good knowledge of the welding residual stress field and the corresponding distortion is needed when the interaction between manufacturing stresses and future (mechanical and/or thermal) design loads is studied, for example, with respect to possible crack initiation and growth in the HAZ, and also with respect to buckling. It is proposed here that a qualitatively good estimate of the welding residual stresses can be obtained by using FEM without following the temperature history during welding and cooling in detail. The procedure proposed is applied to two different problems: multi-pass butt welding of pipes, and spot welding of box beams. For the case of multi-pass butt welding of pipes, experimental results are available and a good agreement with these results is observed.

Experimentally determined transient and residual stresses in a butt-welded pipe

1988 ◽  
Vol 23 (1) ◽  
pp. 25-31 ◽  
Author(s):  
M Jonsson ◽  
B L Josefson
Keyword(s):  
Residual Stresses ◽  
Analytical Solutions ◽  
Stress Fields ◽  
Final Phase ◽  
Residual Stress Field ◽  
Butt Welding ◽  
Rotationally Symmetric ◽  
Surface Deviations ◽  
Welded Pipe ◽  
Good Agreement

Single pass butt-welding of a pipe is studied. Low heat input has been used to obtain high cooling rate with adherent martensite in the final phase transformation in the heat affected zone. Strains and stresses have been measured during and after welding on the pipe outer surface. Deviations from rotationally symmetric strain and stress fields in the pipe are studied. Two different analytical solutions for the residual stress field from the literature are discussed. The experimentally obtained residual stresses are compared with those analytical solutions. Qualitatively good agreement between experiments and analytical solutions was obtained, although the analytical solutions do not consider effects of phase transformations.

The Effects of Loadings on Welding Residual Stresses and Assessment of Fracture Parameters in a Welding Residual Stress Field

2011 ◽  
Author(s):  
Liwu Wei ◽  
Weijing He ◽  
Simon Smith
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Path Dependence ◽  
Welding Residual Stress ◽  
Assessment Procedure ◽  
Fe Model ◽  
J Integral ◽  
Residual Stress Field ◽  
Growing Crack

The level of welding residual stress is an important consideration in the ECA of a structure or component such as a pipeline girth weld. Such a consideration is further complicated by their variation under load and the complexity involved in the proper assessment of fracture mechanics parameters in a welding residual stress field. In this work, 2D axi-symmetric FEA models for simulation of welding residual stresses in pipe girth welds were first developed. The modelling method was validated using experimental measurements from a 19-pass girth weld. The modeling method was used on a 3-pass pipe girth weld to predict the residual stresses and variation under various static and fatigue loadings. The predicted relaxation in welding residual stress is compared to the solutions recommended in the defect assessment procedure BS 7910. Fully circumferential internal cracks of different sizes were introduced into the FE model of the three-pass girth weld. Two methods were used to introduce a crack. In one method the crack was introduced instantaneously and the other method introduced the crack progressively. Physically, the instantaneously introduced crack represents a crack originated from manufacturing or fabrication processes, while the progressively growing crack simulates a fatigue crack induced during service. The J-integral values for the various cracks in the welding residual stress field were assessed and compared. This analysis was conducted for a welding residual stress field as a result of a welding simulation rather than for a residual stress field due to a prescribed temperature distribution as considered by the majority of previous investigations. The validation with the 19-pass welded pipe demonstrated that the welding residual stress in a pipe girth weld can be predicted reasonably well. The relaxation and redistribution of welding residual stresses in the three-pass weld were found to be significantly affected by the magnitude of applied loads and the strain hardening models. The number of cycles in fatigue loading was shown to have little effect on relaxation of residual stresses, but the range and maximum load together governed the relaxation effect. A significant reduction in residual stresses was induced after first cycle but subsequent cycles had no marked effect. The method of introducing a crack in a FE model, progressively or instantaneously, has a significant effect on J-integral, with a lower value of J obtained for a progressively growing crack. The path-dependence of the J-integral in a welding residual stress field is discussed.

A Limiting Defect Study of an Elbow

2011 ◽  
Author(s):  
Jinhua Shi ◽  
David Blythe
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Hoop Stress ◽  
Defect Size ◽  
Welding Residual Stress ◽  
Central Section ◽  
Butt Welding ◽  
Wide Range ◽  
Stress Components ◽  
Hoop Stresses

In order to ensure the integrity of a seamless butt-welding elbow, both the central section and ends of the elbow need to be assessed, as the maximum stress is normally located at the central section of the elbow but there are no welding residual stresses. Furthermore, at the ends (welds) of the elbow, very high welding residual stresses exist if the welds have not been post weld heat treated but the primary stresses induced by the internal pressure and system moments are lower. For a 90 degree elbow welded to seamless straight pipe, both maximum axial and hoop stress components in the elbow can be calculated using ASME III NB-3685. At the ends of the elbow, axial and hoop stress components can be obtained using the stress equations presented in the paper of PVP2010-25055. In this paper, a series of limiting defect assessments have been carried out on an elbow assuming a postulated axial external defect as follows: • A number of assessments have been conducted directly using the axial and hoop stresses calculated based on ASME III NB-3685 for different system moments. • A series of assessments have been carried out using the axial and hoop stresses calculated using the stress equations presented in the paper of PVP2010-25055, a wide range of welding residual stresses and different system moments. A comparison of the assessment results in the elbow and at the ends of the elbow shows that when system moments are relatively low and the welding residual stress is high, the limiting defect size is located at the ends of the elbow; when the system moments are high and the welding residual stress is low the limiting defect size is located at the central section of the elbow. Therefore, it can be concluded that when assessing an elbow, the assessments should be carried out at both the central section and the ends of the elbow, in order to ensure the integrity of the elbow.

Effect of Reeling Installation on Weld Residual Stress in Pipeline Girth Welds

2013 ◽  
Author(s):  
T. Sriskandarajah ◽  
Graeme Roberts ◽  
Daowu Zhou
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Residual Stresses ◽  
Axial Strain ◽  
Saddle Points ◽  
Parent Material ◽  
Welding Residual Stress ◽  
Residual Stress Field ◽  
Weld Residual Stress ◽  
Girth Welds

A characteristic of pipeline installation by the reeling technique is the generation of high plastic strain around the majority of the pipeline’s circumference as it is spooled onto a drum, under displacement controlled conditions. It is well-known that the application of sufficiently high amounts of mechanical or thermal energy will “anneal” (relax) weld residual stresses and, therefore, under the gross plasticity experienced during reeling it should be expected that initial girth weld residual stresses will be entirely relaxed during the first reel cycle. The residual stress state needs to be taken into account in Engineering Critical Assessment (ECA) procedures of girth welds when predicting allowable defect dimensions. ECA codes such as DNV-OS-F101 and BS7910 assume the welding residual stress to be equal to the yield strength of the parent material and relaxation of welding residual stress under overload is allowed. However, the treatment specified in DNV is established from load-controlled scenarios and may result in un-realistic allowable defect dimensions in displacement-controlled situations such as reeling. Welding residual stress in reeling ECA is concerning to the subsea pipeline industry. By performing reeling simulations with 3D finite element analyses (FEA), this paper examines the welding residual stress before and after reeling and assesses the extent of residual stress relaxation. It was found that reeling axial strain causes significant relaxation of the weld residual stress at the pipe intrados and extrados. At the saddle points there is a slight disruption to the residual stress field. The full weld residual stress is relaxed from a value equal to the material yield stress, and is replaced by a plastic deformation induced stress of much lower magnitude, typically in the order of 100 MPa or less. The plastic deformation stress is of equal magnitude whether or not the pipe section contains initial weld residual stress and, therefore, it is concluded that weld residual stress can be ignored following the first reel cycle.

Effect of Welding Parameters on Temperature Distribution During Friction Stir Spot Welding of Commercial Pure Copper Lap Joint

2018 ◽  
Author(s):  
Ahmed Mahgoub ◽  
Abdelaziz Bazoune ◽  
Fadi Al-Badour ◽  
Necar Merah ◽  
Abdelrahman Shuaib
Keyword(s):  
Rotational Speed ◽  
Spot Welding ◽  
Dwell Time ◽  
Pure Copper ◽  
Friction Stir Spot Welding ◽  
Temperature History ◽  
Welding Parameters ◽  
Deformation Model ◽  
Friction Stir ◽  
Good Agreement

In this paper, a Coupled Eulerian Lagrangian (CEL) finite element model (FEM) was developed to simulate the friction stir spot welding (FSSW) of commercial pure copper. Through simulations results, the paper presents and discusses the effect of FSSW process parameters; namely rotational speed, plunging rate and dwell time, on the developed temperatures and their distribution within the workpiece as well as material flow and deformation. Model validation showed a good agreement between predicted temperature history and the experiment one, with a maximum error of 6%. Furthermore, the predicted formation of flash was also found in good agreement with the experiment with an error of only 7%. Simulation results predicted peak temperature and plastic strain among all studied welding conditions were 920 K and 3.5 respectively at 1200 rpm rotational speed, 20 mm/min plunging rate and 4 seconds dwell time, which is approximately 70% of the melting point of pure copper.

Residual Stress Measurements in Single and Multi-Pass Groove Weld Specimens Using Neutron Diffraction and the Contour Method

2006 ◽  
Vol 524-525 ◽  
pp. 671-676 ◽  
Author(s):  
M. Kartal ◽  
Mark Turski ◽  
Greg Johnson ◽  
Michael E. Fitzpatrick ◽  
S. Gungor ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Cross Section ◽  
Welding Process ◽  
Contour Method ◽  
Residual Stress Field ◽  
Process Measurements ◽  
Good Agreement

This paper describes the measurement of longitudinal residual stresses within specially designed 200x180x25mm groove weld specimens. The purpose of these measurements was to compare the residual stress field arising from single and multi-pass weld beads laid down within the constraint of a groove in order to validate finite element simulations of the welding process. Measurements were made over the cross section at the mid-bead length, utilising the relatively new Contour method and neutron diffraction. Results from these measurements indicate a larger peak tensile longitudinal residual stresses within the weld region of the multi-pass weld sample. Good agreement is found between both techniques.

scholarly journals On the Influence of Welding Residual Stresses on the Dynamic Behavior of Structures

2008 ◽  
Vol 15 (3-4) ◽  
pp. 447-458 ◽  
Author(s):  
A.C. Bezerra ◽  
L.C. Vieira ◽  
D.A. Rade ◽  
A. Scotti
Keyword(s):  
Residual Stresses ◽  
Dynamic Behavior ◽  
Dynamic Characteristics ◽  
Thermal Loading ◽  
Welding Residual Stress ◽  
Temperature History ◽  
Transient Temperature ◽  
Geometric Distortions ◽  
Welding Processes ◽  
Stiffening Effect

It is widely known that welding processes induce the generation of residual stresses, which, through the so-named stress stiffening effect, can influence the static and dynamic behavior of the welded components. Thus, accounting for this influence becomes important for the understanding of experimental observations and accurate modeling of the dynamic behavior. In this study, the numerical and experimental characterization of the influence of welding residual stresses on the flexural dynamic characteristics of rectangular plates is addressed. It is suggested a general modeling methodology based on finite elements comprising three subsequent analyses, namely: a thermal analysis to compute the transient temperature history due to welding thermal loading; a structural analysis accounting for plastic strains to obtain the welding residual stress fields and geometric distortions, and a dynamic analysis to compute the dynamic characteristics taking into account the stress-stiffening effect and geometric distortions. The results demonstrate the importance of considering the influence of welding residual stresses in the prediction of the flexural dynamic behavior of plates and the feasibility and efficiency of the simplified modeling approach, which can readily be extended to more complex situations, for characterizing this influence.

scholarly journals Simulation of Multipass Welding With Simultaneous Computation of Material Properties

2000 ◽  
Vol 123 (1) ◽  
pp. 106-111 ◽  
Author(s):  
Lars Bo¨rjesson ◽  
Lars-Erik Lindgren
Keyword(s):  
Residual Stresses ◽  
Microstructure Evolution ◽  
Material Properties ◽  
Base Material ◽  
Steel Plates ◽  
Filler Material ◽  
Temperature History ◽  
Temperature Dependent ◽  
Butt Welding ◽  
Thick Steel

Multipass butt welding of two 0.2 m thick steel plates has been investigated. The objective is to calculate residual stresses and compare them with measured residual stresses. The material properties depend on temperature and temperature history. This dependency is accounted for by computing the microstructure evolution and using this information for computing material properties. This is done by assigning temperature dependent material properties to each phase and applying mixture rules to predict macro material properties. Two different materials have been used for the microstructure calculation, one for the base material and one for the filler material.

scholarly journals Numerical Investigation of Welding Residual Stress Field and its Behaviour under Multiaxial Loading in Tubular Joints

2014 ◽  
Vol 996 ◽  
pp. 788-793
Author(s):  
Kimiya Hemmesi ◽  
Majid Farajian ◽  
Dieter Siegele
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Weld Zone ◽  
Welding Residual Stress ◽  
Multiaxial Loading ◽  
Residual Stress Field ◽  
Tubular Joints ◽  
Welded Structure

The lack of clarities in estimating the residual stress threat to the structural integrity has led to conservative assumptions in the current design of welds. The complexities become more in the case of multiaxial loading of welded structure, considering fracture or fatigue. To what extent the residual stresses influence the performance of a welded structure, depends on how stable they are under service loads. Finite element analyses are used here to describe the development of welding residual stresses in tubular joints and their relaxation under multiaxial loading. It is observed that the effect of the torsion load is more significant than the effect of tension load in releasing of the residual stresses. For pure tensile loading, the relaxation of the residual stresses are negligible as long as the applied load is lower than 50% of the yield strength of the material. For a combined tension-torsion loading of 75% of the yield strength, the residual stresses are almost completely released, and in the weld zone they become compressive.

Application of 3D Finite Element Modelling to Repair Weld Simulation in Industrial Applications

2002 ◽  
Author(s):  
George Vinas ◽  
Tamba Dauda ◽  
Nicola Moyes ◽  
Alan Laird
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Measurement Techniques ◽  
Fem Simulation ◽  
Welding Process ◽  
Industrial Applications ◽  
Welding Residual Stress ◽  
Experimental Techniques ◽  
Residual Stress Field

The Finite Element Method (FEM) has been implemented in 3D to predict welding residual stresses in repair welds. The analysis has been used to achieve more accurate residual stress predictions for the weld at the cost of long computation times. The use of this CPU intensive approach has been facilitated by the advent of ever-faster computer processors being made more accessible to the engineering community. The same technique has also been used with coarser meshes involving simplified welding sequences where a number of weld passes are “lumped” together to reduce the simulation time. The authors argue that this latter approach can be very useful in predicting the more global component response — in cases where 2D model symmetries are not applicable — and for rapid identification of problem areas where finer simulations would be prohibitive. The authors show an example of a residual stress prediction for a letterbox repair obtained using the FEM. Good agreement between this prediction and experimental measurements is shown. The FEM simulation technique has been used to predict residual stress formation during the welding process and subsequent service loading of the component. This analysis shows the residual stress field relaxation following “shakedown”. The component under service conditions is subjected to pressure loading and a small amount of bending stress. Based on recent residual stress experimental programmes conducted at Mitsui Babcock Energy Limited (MBEL), the authors provide a brief discussion on the ways in which various experimental techniques have been used to verify welding residual stress predictions from FE. The authors argue that just as there has been an interest in the field to measure residual stresses in the highly stressed regions of a weld, it is equally important to measure stresses in areas of relatively low stress to confirm that stresses do indeed die out away from welds. It is in the latter case where some experimental techniques cannot perform as well as other simple, well proven, strain measurement techniques.

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