Analysis of circumferentially welded thin-walled cylinders to study the effects of tack weld orientations and joint root opening on residual stress fields

2009 ◽  
Vol 223 (5) ◽  
pp. 1037-1049 ◽  
Author(s):  
N U Dar ◽  
E M Qureshi ◽  
A M Malik ◽  
M M I Hammouda ◽  
R A Azeem
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Arc Welding ◽  
Operating Conditions ◽  
Stress Fields ◽  
Welded Structures ◽  
Prime Concern ◽  
Thin Walled ◽  
Tack Weld ◽  
Welding Processes

In recent years, the demand for resilient welded structures with excellent in-service load-bearing capacity has been growing rapidly. The operating conditions (thermal and/or structural loads) are becoming more stringent, putting immense pressure on welding engineers to secure excellent quality welded structures. The local, non-uniform heating and subsequent cooling during the welding processes cause complex thermal stress—strain fields to develop, which finally leads to residual stresses, distortions, and their adverse consequences. Residual stresses are of prime concern to industries producing weld-integrated structures around the globe because of their obvious potential to cause dimensional instability in welded structures, and contribute to premature fracture/failure along with significant reduction in fatigue strength and in-service performance of welded structures. Arc welding with single or multiple weld runs is an appropriate and cost-effective joining method to produce high-strength structures in these industries. Multi-field interaction in arc welding makes it a complex manufacturing process. A number of geometric and process parameters contribute significant stress levels in arc-welded structures. In the present analysis, parametric studies have been conducted for the effects of a critical geometric parameter (i.e. tack weld) on the corresponding residual stress fields in circumferentially welded thin-walled cylinders. Tack weld offers considerable resistance to the shrinkage, and the orientation and size of tacks can altogether alter stress patterns within the weldments. Hence, a critical analysis for the effects of tack weld orientation is desirable.

Residual Stresses in As-Welded Joints: Finite Element Modeling and Neutron Difraction Stress Measurements

2011 ◽  
Vol 488-489 ◽  
pp. 335-338 ◽  
Author(s):  
Claire Acevedo ◽  
Jean Marie Drezet ◽  
J. P. Lefebvre ◽  
Laurent D'Alvise ◽  
A. Nussbaumer
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Arc Welding ◽  
Analysis Method ◽  
Weld Joints ◽  
Stress Components ◽  
Bridge Joints ◽  
Nonlinear Transient ◽  
Welding Processes

This paper describes the numerical analysis method used to estimate welding induced residual stresses in K-shape tubular bridge joints. The knowledge of residual stress distribution is required to design the geometry of K-joints loaded under fatigue stresses. Numerical simulations are focused on the arc welding MAG process, generally used to weld joints in bridge construction. Thermo-mechanical analyses are performed in 3D using two finite element codes:ABAQUS® and MORFEO® . ABAQUS has the advantage to offer large analysis capabilities(nonlinear, transient, dynamic, etc.) whereas MORFEO is more dedicated to welding processes and offers the possibility to analyze crack propagation under fatigue loads. Computed residual stresses in the region surrounding the weld are compared with measured residual stresses in order to estimate the ability of the codes to reproduce these stresses. Position, orientation and magnitude of the highest residual stress components are discussed.

Methodology for Numerical Welding Simulation Validation: The Dissimilar Metal Weld Case

2013 ◽  
Author(s):  
Ph. Gilles ◽  
S. Courtin ◽  
R. Vincent ◽  
M. Yescas ◽  
F. Gommez
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Welding Residual Stress ◽  
Stress Fields ◽  
Design Stage ◽  
Connected Components ◽  
Actual State ◽  
Cycle Fatigue ◽  
Dissimilar Metal ◽  
Welding Processes

Welding processes induce residual stresses and distortion in the welded joint and the connected components. For manufacturing purpose distortion is the main issue and up to now the problem is handled by post weld corrective actions. Welding residual stress fields are not considered at the design stage in French codes and standards. However, it is well known that residual stresses are likely to increase the risks of fatigue or corrosion and may cause failure in brittle materials. Ferritic parts of large components are post-weld heat treated; allowing disregarding the influence of residuals stresses thanks to their relief. Preventive measures, including mitigation by fine polishing are undertaken in corrosion sensitive zones. The influence of residual stresses on fatigue is more complex to analyze: in low cycle fatigue, residual stresses should be relieved or redistributed after few cycles with plastic straining, and for high cycle fatigue, residual stress effects are accounted for through a mean stress offsett. When considered, residual stress fields are often represented in a very crude manner by a membrane distribution of the most influent stress component through the thickness of the structure. In a less rough way, several codes or fitness-for-purpose guidelines (API [1], British standards [2]) propose residual stress profiles relative to several weld configurations. Nevertheless for a given case, the given profiles may differ significantly for several reasons: the degree of conservatism, the number of covered cases, the embedded margins accounting for uncertainties. Some ill-posed benchmark problems have shown that numerical simulation of residual stresses may deliver very scattered results. AREVA has therefore developed a methodology to validate welding simulations. The scope is limited to fusion welding. The simulations are based on a Thermo-Metallurgical Mechanical model in which the welding energy is represented by an equivalent heat source. This paper presents the actual state of development of this methodology which will be illustrated through 4 examples of residual fields in Dissimilar Metal Welds. Residual stress measurements have been performed for each of the four mock-ups by different techniques. Based on this important experimental and numerical campaign some actions of improvement of the validation methodology are finally listed.

Residual Stress Fields Under Different Clamping Conditions in Circumferentially Welded Thin-Walled Cylinders

2008 ◽  
Author(s):  
Afzaal M. Malik ◽  
Ejaz M. Qureshi ◽  
Naeem Ullah Dar ◽  
Iqbal Khan
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Corrosion ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Pressure Vessels ◽  
Stress Fields ◽  
Shop Floor ◽  
High Tech ◽  
Thin Walled

Arc welding is a reliable joining method widely utilized in nuclear, pressure vessels, aerospace and aeronautical structures to ensure the intended in service behaviour during the thermal and/or pressure loadings. Weld induced deformations and high residual stresses often occur during the course of welding. These cause significant threats for the structural integrity of the nuclear power plant components, particularly in stress corrosion inhibited environments owing to the risk of stress corrosion cracking (SCC). In this research, the consequences of five different structural boundary conditions on the evolution of residual stress fields after the welding are investigated. Both experimental and numerical simulations based on finite element modeling are employed during the course of investigation. Full three-dimensional FE models for the circumferentially, arc welded thin-walled cylinders are developed in ANSYS®. The complex coupled, thermo-mechanical phenomenon during the welding is simulated by sequentially coupled approach enhanced by user written APDL subroutines. The role of welding restraints in minimizing / optimizing the residual stresses is presented and discussed in detail. The result reveals that residual stresses show weak dependence on the degree of the restraints. Although the stress levels slightly varies in magnitude, but similar trend is observed for all the structural clamping conditions under study. Simulation results validated through full-scale experiments with high-tech reliably instrumented welding and measuring equipments shows promising features of the developed modelling and simulation strategy for use in shop floor applications.

The Effect of Modelling Simplifications on the Prediction of Residual Stresses in Thin-Walled Pipe Butt Welds

2006 ◽  
Author(s):  
A. P. Warren ◽  
S. K. Bate ◽  
R. Charles ◽  
D. M. O’Gara ◽  
P. M. Wood ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Computational Power ◽  
Butt Weld ◽  
Butt Welds ◽  
Thin Walled Pipe ◽  
Thin Walled ◽  
Predicted Values ◽  
Welding Processes

The inherent complexity of modelling welding processes and the lack of computational power available to analysts has resulted in simplified methods being commonly utilised when predicting residual stresses. Despite considerable advances in computational power, it is still often not possible to run detailed 3D analyses of complex welded geometries within practical timescales. Against this background, a programme of work has been undertaken to develop a weld modelling procedure which can be followed by analysts. This procedure will account for how various modelling simplifications affect the predicted values of residual stress. One common geometry, which it is often necessary to analyse using modelling simplifications is that of a thin-walled pipe butt weld. Typically this geometry is simulated using a 2D axisymmetric analysis. Despite the popularity of this modelling simplification the effects of its use are not fully understood. In order to feed into this procedure, work has therefore been conducted to better understand the effects modelling simplifications will have on the residual stress levels that are predicted when simulating multi-pass pipe butt welds. The geometry considered in this study is the thin walled austenitic pipe butt weld specimen originally studied in VORSAC 5th Framework European Union project. This paper presents the results of a number of finite element analyses conducted of this geometry. These analyses have been conducted using a combination of the finite element codes SYSWELD and ABAQUS. The aim of this study was to understand the effect that the use of 2D axisymmetric analyses, and other modelling simplifications, namely block dumping and bead lumping will have on the predicted values of residual stress.

Measurements of Residual Stresses Using Mechanical Strain Relaxation Methods and Mapping in a Thin-Walled Girth Welded Pipe Mock-Up

2016 ◽  
Author(s):  
Karim Serasli ◽  
Remi Romac ◽  
Douglas Cave
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Mechanical Strain ◽  
Contour Method ◽  
Hole Drilling ◽  
Mapping Technique ◽  
Thin Walled ◽  
Welded Pipe ◽  
Welding Processes

Girth welded pipes such as those located offshore on platforms in the North Sea are subjected to highly corrosive environment. The need to consider welding residual stresses in the assessment of the fitness for service and damages to these pipes when investigating local corrosion damages across a welded region is therefore important for the operators of the platforms and the manufacturers of the pipes. This paper presents a review of work carried out to ascertain the welding residual stresses present within a thin-walled girth welded pipe mock-up made from steel API 5LX Grade 52. The mock-up was manufactured to replicate typical pipes used to convey gas, oil and water through the platforms. The mock-up was of diameter 762mm and of thickness 19mm. The incremental deep hole drilling (iDHD) technique and the contour method were applied to characterize the residual stresses in the weld and heat affected zone of the specimen. The results of these measurements are presented and compared to highlight agreements and discrepancies in the measured residual stress distributions using these different techniques. Most residual stress measurement methods are limited in terms of their stress and spatial resolution, the number of measurable stress tensor components and their quantifiable measurement uncertainty. In contrast, finite element simulations of welding processes provide full field distributions of residual stresses, with results dependent on the quality of the input conditions available. As measurements and predictions are not often the same, the true residual stress state is therefore difficult to determine. In this paper, through-thickness residual stress measurements are made using the contour and iDHD methods and these residual stresses measured using the iDHD technique are then used as input to a residual stress mapping technique provided within a finite element analysis to reconstruct the residual stress field in the whole specimen. The technique is applied iteratively to converge to a balanced solution which is not necessarily unique. The solution can then be reused for further simulations and residual stress analyses, such as corrosion simulation. Results of the reconstruction are presented here.

Numerical Methods to Predict Distortion in Welded Components

2008 ◽  
Author(s):  
N. A. Leggatt ◽  
R. J. Dennis ◽  
P. J. Bouchard ◽  
M. C. Smith
Keyword(s):  
Residual Stress ◽  
Numerical Methods ◽  
Structural Integrity ◽  
Large Strain ◽  
Stress Fields ◽  
Specimen Thickness ◽  
Single Bead ◽  
Stress Profiles ◽  
Welding Processes ◽  
Integrity Assessments

Numerical methods have been established to simulate welding processes. Of particular interest is the ability to predict residual stress fields. These fields are often used in support of structural integrity assessments where they have the potential, when accurately characterised, to offer significantly less conservative predictions of residual profiles compared to those found in assessment codes such as API 579, BS7910 and R6. However, accurate predictions of residual stress profiles that compare favourably with measurements do not necessarily suggest an accurate prediction of component distortions. This paper presents a series of results that compare predicted distortions for a variety of specimen mock-ups with measurements. A range of specimen thicknesses will be studied including, a 4mm thick DH-36 ferritic plate containing a single bead, a 4mm thick DH-36 ferritic plate containing fillet welds, a 25mm thick 316L austenitic plate containing a groove weld and a 35mm thick esshete 1250 austenitic disc containing a concentric ring weld. For each component, distortion measurements have been compared with the predicted distortions with a number of key features being investigated. These include the influence of ‘small’ vs ‘large’ strain deformation theory, the ability to predict distortions using simplified analysis methods such as simultaneous bead deposition and the influence of specimen thickness on the requirement for particular analysis features. The work provides an extremely useful insight into how existing numerical methods used to predict residual stress fields can be utilised to predict the distortions that occur as a result of the welding fabrication process.

Analysis of circumferentially arc welded thin-walled cylinders to investigate the residual stress fields

2008 ◽  
Vol 46 (12) ◽  
pp. 1391-1401 ◽  
Author(s):  
Afzaal M. Malik ◽  
Ejaz M. Qureshi ◽  
Naeem Ullah Dar ◽  
Iqbal Khan
Keyword(s):  
Residual Stress ◽  
Stress Fields ◽  
Thin Walled

Investigation of Welded Joints Made of Construction Steel by the Barkhausen Noise Method

2020 ◽  
Vol 992 ◽  
pp. 957-963
Author(s):  
E. Nikolaeva ◽  
A. Nikolaev
Keyword(s):  
Stress State ◽  
Residual Stresses ◽  
Welded Joints ◽  
Arc Welding ◽  
Barkhausen Noise ◽  
Low Carbon ◽  
Butt Weld ◽  
Welded Structures ◽  
The Relationship ◽  
Weld Seams

Steel weld seams are characterized by heterogeneity of their microstructure. Microstructure affects the nature of the distribution, sign and magnitude of residual stresses. In combination with unfavorable factors (low temperature, metal hypoductility and an unsuccessful joint form) residual stresses lead to a decrease of load carrying capacity of a whole structure. In a weld seam residual stresses are distributed in a complex way and can affect the build quality of heavy section welded structures. Monitoring of residual stresses remains a big problem. Residual stresses in welds are often evaluated only by modeling. Unfortunately, all mathematical models describe the stress state of the welded material with low accuracy. Simple quality control, the results of which can be easy interpreted, is necessary. Welded joints made by manual arc welding and by automatic submerged arc welding were investigated. Butt seams of steel sheets of different thickness have been welded. Steel was low-carbon and low-alloyed. It is often used in welded structures for various purposes, including construction, and for pipelines manufacture. The temperature range of welded structures operation is very large – from-70 to 450С. The authors studied the structure of butt weld seams by the Barkhausen noise method, which is interesting as it represents an alternative to the known methods, which characterizes the structure and stress state of material. The relationship between the weld microstructure and magnetic noise is shown. Studies have allowed us to establish the relationship between the structure and magnetic properties and to evaluate the feasibility of applying the Barkhausen noise method to welded structures.

Fast Three-Dimensional Finite Element Analysis of Weld Overlay Application on a Formed Feeder Elbow

2011 ◽  
Author(s):  
Francis H. Ku ◽  
Pete C. Riccardella
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Nuclear Reactor ◽  
Three Dimensional ◽  
Fe Method ◽  
Element Analysis ◽  
Weld Overlay ◽  
Welding Processes

This paper presents a fast finite element analysis (FEA) model to efficiently predict the residual stresses in a feeder elbow in a CANDU nuclear reactor coolant system throughout the various stages of the manufacturing and welding processes, including elbow forming, Grayloc hub weld, and weld overlay application. The finite element (FE) method employs optimized FEA procedure along with three-dimensional (3-D) elastic-plastic technology and large deformation capability to predict the residual stresses due to the feeder forming and various welding processes. The results demonstrate that the fast FEA method captures the residual stress trends with acceptable accuracy and, hence, provides an efficient and practical tool for performing complicated parametric 3-D weld residual stress studies.

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