Numerical Simulation of the Weld Residual Stresses for a Man-Hole Drainage Nozzle in a Steam Generator: Design Comparison

2007 ◽  
Author(s):  
Tomas Nicak ◽  
Matthias Hu¨mmer ◽  
Elisabeth Keim
Keyword(s):  
Residual Stresses ◽  
Steam Generator ◽  
Welding Process ◽  
Life Time ◽  
3D Models ◽  
3D Analysis ◽  
Welding Simulation ◽  
Abaqus Code ◽  
Transient Thermal ◽  
Design Options

The numerical welding simulation has developed very rapidly during the last few years. The problem complexity has increased from simple 2D axis-symmetric or cross-section models to full 3D models, which can describe the entire welding process more realistically — including start-stop effects. As recent research projects indicate, a quantitative assessment of the residual stresses magnitude by means of a 3D analysis is possible. Moreover, the structure integrity with respect to fatigue, fracture or Stress Corrosion Cracking (SCC) processes can be evaluated based on the welding simulation results superimposed with the operating load (or any arbitrary disturbance transient load). This makes a more accurate life time prediction of the welded components possible. Furthermore, in order to minimize the residual stresses in components, a parametric study can be performed considering important input data like heat input or bead sequencing. It would make the development of virtual welding procedures possible, which can essentially help to cut the design and operating costs. In this paper a full 3D numerical welding simulation for a man-hole drainage nozzle in a steam generator will be presented. Two design options are considered. The residual stresses are calculated by means of an uncoupled transient thermal and mechanical FE analysis using the ABAQUS code. The paper will present a robust procedure allowing reasonable predictions of the residual stresses for complex structures in industrial practice.

Study of the Effect of Boundary Conditions on Residual Stresses in Welding Using Element Birth and Element Movement Techniques

2003 ◽  
Author(s):  
Ihab F. Z. Fanous ◽  
Maher Y. A. Younan ◽  
Abdalla S. Wifi
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Boundary Conditions ◽  
Welding Process ◽  
Computation Time ◽  
3D Models ◽  
The Other ◽  
3D Analysis ◽  
The Media ◽  
Element Movement

The structure in which the welding process is performed highly affects the residual stresses generated in the welding. This effect is simulated by choosing the appropriate boundary conditions in modeling the welding process. The major parameters of the boundary conditions are the method by which the base metal is being fixed and the amount of heat being applied through the torch. Other parameters may include the coefficients of thermal heat loss from the plate which may simulate the media in which the welding is taking place. In modeling the welding process, 2D forms of approximation were developed in analyzing most of the models of such problem. 3D models analyzing the welding process were developed in limited applications due to its high computation time and cost. With the development of new finite element tools, namely the element movement technique developed by the authors, full 3D analysis of the welding process is becoming in hand. In the present work, three different boundary conditions shall be modeled companng their effect on the welding. These boundary conditions shall be applied to two models of the welding process: one using the element birth technique and the other using the element movement technique showing the similarity in their responses verifying the effectiveness of the latter being accomplished in a shorter time.

Analysis of Residual Stresses in a Pressurizer Surge–Nozzle Weldment

2011 ◽  
Author(s):  
Florian Obermeier ◽  
Tomas Nicak ◽  
Gottfried Meier ◽  
Elisabeth Keim
Keyword(s):  
Residual Stresses ◽  
Material Model ◽  
Round Robin ◽  
Pressurized Water Reactor ◽  
Element Analysis ◽  
Pressurized Water ◽  
Piping Systems ◽  
Primary Water ◽  
Abaqus Code ◽  
Transient Thermal

Residual stresses and distortion of welded structures have a significant influence on their functionality and their lifetime. In Pressurized Water Reactor (PWR) piping systems, residual stresses in dissimilar metal welds extensively increase their susceptibility to primary water stress corrosion cracking (PWSCC). An accurate crack initiation and growth assessment is essential to assure that no severe component failure will occur due to SCC or any other stress induced mechanism. Therefore it is necessary to develop methods for a proper residual stress and distortion prediction. Numerical welding simulations have developed fast during the recent years but no universally accepted guidelines for a reliable prediction of residual stresses have been established so far. In order to support further validation of developed methods the U.S. NRC launched an international round robin program. Its main intention is to benchmark different numerical approaches by direct comparison with experimental data obtained from a provided mock-up. This paper shows the contribution of AREVA NP Germany to this round robin. A two dimensional axis-symmetric analysis of a pressurizer surge nozzle – safe end – pipe weldment will be presented. The residual stresses are calculated by means of an uncoupled transient thermal and mechanical finite element analysis using the ABAQUS Code. In addition some comments on the selection of the material model and its effect on the resulting residual stresses will be given.

Estimation of Weld Induced Residual Stresses of Thick Welded Sections Using Numerical Welding Simulation

2013 ◽  
Author(s):  
Yogendra (San) Gooroochurn ◽  
Philippe Thibaux ◽  
Steven Cooreman ◽  
Joachim Antonissen
Keyword(s):  
Residual Stresses ◽  
Permanent Deformation ◽  
Welding Process ◽  
Complex Phase ◽  
Welding Simulation ◽  
Uniform Contraction ◽  
Multiple Variables ◽  
Physical Phenomena ◽  
Welding Processes ◽  
Contraction And Expansion

Welding processes are quite complex in nature as they involve the interaction of multiple physical phenomena. The thermal history developed during the process causes the material to undergo complex phase transformations. Non-uniform contraction and expansion of heat affected, softer, areas constrained by cooler, harder, areas of the material induce residual stresses and the weldment undergoes permanent deformation. When thick sections are welded, the formation of phases and the distribution of residual stresses are even more complex. These could lead to failure of the welded components during service. For the design of pressure vessel applications understanding the phase formation and residual stress distribution in thick weldments is critical. Numerical simulation was used to understand the influence of multiple variables on the residual stresses induced by a welding process The challenges involved in performing welding simulation of thick sections are described. Furthermore numerical and experimental results are compared and discussed.

scholarly journals Effect of Boundary Conditions on Residual Stresses and Distortion in 316 Stainless Steel Butt Welded Plate

2019 ◽  
Vol 38 (2019) ◽  
pp. 827-836 ◽  
Author(s):  
Dhayanithi Venkatkumar ◽  
Durairaj Ravindran
Keyword(s):  
Thermal Analysis ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Welding Process ◽  
Physical And Mechanical Properties ◽  
Mechanical Analysis ◽  
Distribution Model ◽  
Fe Method ◽  
Thermal Histories ◽  
Transient Thermal

AbstractIn the present work, the prediction of residual stresses and distortion due to GTA welding process, a Finite Element (FE)Method has been developed and applied. Stainless steel plate of 3mm thickness is taken for the analysis. The prediction of residual stresses and distortion is performed by thermal and mechanical analysis that is sequentially coupled. The thermal analysis and mechanical analysis of the plate subjected to heat source movement have been studied consecutively. The FE analysis is performed in ANSYS software. In transient thermal analysis, Gaussian distribution model has been used for heat input of the arc. During modeling, the physical and mechanical properties that depend on temperature are considered. The heat transfer losses through all the three mechanisms are incorporated. For validating the FE simulated analysis, an experiment is conducted. The predicted thermal histories are very close agreement with measured thermocouple readings. After validation of thermal analysis results, the transient thermal histories are used as input for further mechanical analysis to simulate. The large displacement theory is used to conduct mechanical analysis. The effect of constraints on distortion and residual stresses are numerically studied. The predicted stresses and distortion results of different cases are discussed and presented.

scholarly journals Welding Simulation Used in the Design of Metallic Armor Systems

2014 ◽  
Vol 996 ◽  
pp. 518-524
Author(s):  
Lee Fredette ◽  
Elvin Beach
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Finite Element Simulation ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Welding Process ◽  
Welding Simulation ◽  
Finite Element Software ◽  
Element Simulation ◽  
Wide Range

Welding steel armor reduces the armor materials protection capability. Several industrial and military welding standards exist for welding armor materials with the primary focus on joint strength rather than ballistic integrity.The Heat Affected Zone (HAZ) created by the welding process introduces vulnerabilities in the protection system. The process and designs that we have demonstrated include mitigation features that eliminate the ballistic degradation and provide uniform protection across all armor materials.In this study we used finite element simulation of the welding process to perform trade studies evaluating welded joint designs, and to show how the designs could be altered to both optimize armor performance and reduce welding heat input. A beneficial effect of reduced heat input was the corresponding reduction in welding-induced residual stresses, an overall reduction in assembly distortion in the assembly, and improvement of the armor performance.The simulated welding process included the creation of the heat affected zone and the development of residual stresses in the structure. ABAQUS finite element software was used for the simulation with the aid of an extensive material property database created over the wide range of welding temperatures.The finite element simulation predictions were validated and verified with excellent results by metallography and micro-hardness measurements. Live-fire ballistic tests were used as the final proof of measurable design improvements. Finite element welding simulation was shown to be an effective tool for improving upon standard welded armor designs, and above all in improving human safety.

The Welding Process as a Local Issue with Global Consequences

2014 ◽  
Vol 969 ◽  
pp. 340-344 ◽  
Author(s):  
Mohamad Al Ali
Keyword(s):  
Residual Stresses ◽  
High Temperatures ◽  
Research Program ◽  
Local Stability ◽  
Thermal Stresses ◽  
Welding Process ◽  
Plastic Strains ◽  
Heating And Cooling ◽  
Uneven Heating ◽  
Transient Thermal

The welding process causes transient thermal stresses and non-continuous plastic strains around the weld due to the induced high temperatures. Uneven heating and cooling during the welding process cause a residual stresses in the welded member. The paper deals with the local influence of welding process and its global consequences at the creation and final redistribution of welding stresses. The paper also presents a verification of Modified empirical formulae, developed by the author, using experimental results of research program oriented to the effects of welding stresses and beams local stability [1, 2 and 3].

Analysis of thermal stresses and its effect in the multipass welding process of SS316L

2020 ◽  
pp. 095440892096506
Author(s):  
Harinadh Vemanaboina ◽  
Suresh Akella ◽  
AC Uma Maheshwer Rao ◽  
Edison Gundabattini ◽  
Ramesh Kumar Buddu
Keyword(s):  
Residual Stresses ◽  
Arc Welding ◽  
Thermal Stresses ◽  
Parametric Design ◽  
Welding Process ◽  
X Ray Diffraction ◽  
Gas Tungsten Arc ◽  
Compressive Stresses ◽  
Transient Thermal ◽  
Zone Pass

In this work, simulation has been carried out for multipass Gas tungsten Arc Welding of SS316L and their effects were studied for thermal, and residual stresses and compared with experimental results. The sequentially coupled thermo-mechanical, transient thermal and static structural analysis was modelled using ANSYS with relevant Ansys Parametric Design Language coding. Infrared thermography camera was used to obtain the real time temperatures during the welding. The effect of temperatures and the induced residual stresses of the weldment is measured with X-Ray diffraction technique. Tensile residual stresses have been identified at fusion zone and compressive stresses at heat affected zone. Pass wise temperature measurements were taken from analysis and experiment the agreement with 7.24%. The agreement of measured and analysed residual stress had an agreement with 16.66%.

scholarly journals Digital 3D models of theropods for approaching body-mass distribution and volume

2021 ◽  
Author(s):  
Matías Reolid ◽  
Francisco J. Cardenal ◽  
Jesús Reolid
Keyword(s):  
Body Length ◽  
Heat Dissipation ◽  
Volume Ratio ◽  
3D Models ◽  
The Body ◽  
3D Analysis ◽  
Skull Length ◽  
Knowing That ◽  
Fossil Bones ◽  
Primitive Forms

AbstractThe aim of this work is to obtain diverse morphometric data from digitized 3D models of scientifically accurate palaeoreconstructions of theropods from eight representative families. The analysed polyvinyl chloride (PVC) models belong to the genera Coelophysis, Dilophosaurus, Ceratosaurus, Allosaurus, Baryonyx, Carnotaurus, Giganotosaurus, and Tyrannosaurus. The scanned 3D models were scaled considering different body-size estimations of the literature. The 3D analysis of these genera provides information on the skull length and body length that allows for recognition of major evolutionary trends. The skull length/body length in the studied genera increases according with the size of the body from the smallest Coelophysis with a ratio of 0.093 to ratios of 0.119–0.120 for Tyrannosaurus and Giganotosaurus, the largest study theropods. The study of photogrammetric 3D models also provides morphometric information that cannot be obtained from the study of bones alone, but knowing that all reconstructions begin from the fossil bones, such as the surface/volume ratio (S/V). For the studied theropod genera surface/volume ratio ranges from 35.21 for Coelophysis to 5.55 for Tyrannosaurus. This parameter, closely related to the heat dissipation, help in the characterization of the metabolism of extinct taxa. Accordingly, slender primitive forms of the Early Jurassic (i.e. Coelophysis and Dilophosaurus) had relatively smaller skulls and higher mass-specific metabolic rates than the robust large theropods of the Cretaceous (i.e. Giganotosaurus and Tyrannosaurus). This work presents a technique that, when applied to proper dinosaur models, provides extent and accurate data that may help in diverse study areas within the dinosaur palaeontology and palaeobiology.

scholarly journals Accuracy of cup placement in total hip arthroplasty by means of a mechanical positioning device: a comprehensive cadaveric 3d analysis of 16 specimens

2019 ◽  
pp. 112070001987482
Author(s):  
Arthur J Kievit ◽  
Johannes G G Dobbe ◽  
Wouter H Mallee ◽  
Leendert Blankevoort ◽  
Geert J Streekstra ◽  
...  
Keyword(s):  
3D Models ◽  
Safe Zone ◽  
3D Analysis ◽  
Anterior Pelvic Plane ◽  
Mechanical Device ◽  
Acetabular Cup ◽  
Anteversion Angle ◽  
Positioning Device ◽  
The Mean ◽  
Safe Zones

Introduction: We tested whether a mechanical device (such as Hipsecure) to pinpoint the anterior pelvic plane (APP) as a guide can improve acetabular cup placement. To assess accuracy we asked: (1) is the APP an effective guide to position acetabular cup placement within acceptable ° of divergence from the optimal 40° inclination and 15° anteversion; (2) could a mechanical device increase the number of acetabular cup placements within Lewinnek’s safe zone (i.e. inclination 30° to 50°; anteversion 5° to 25°)? Methods: 16 cadaveric specimens were used to assess the 3D surgical success of using a mechanical device APP to guide acetabular cup placement along the APP. We used the Hipsecure mechanical device to implant acetabular cups at 40° inclination and 15° anteversion. Subequently, all cadaveric specimens with implants were scanned with a CT and 3D models were created of the pelvis and acetabular cups to assess the outcome in terms of Lewinnek’s safe zones. Results: The mean inclination of the 16 implants was 40.6° (95% CI, 37.7–43.4) and the mean anteversion angle was 13.4° (95% CI, 10.7–16.1). All 16 cup placements were within Lewinnek’s safe zone for inclination (between 30° and 50°) and all but 2 were within Lewinnek’s safe zone for anteversion (between 5° and 25°). Conclusion: In cadaveric specimens, the use of a mechanical device and the APP as a guide for acetabular cup placement resulted in good positioning with respect to both of Lewinnek’s safe zones.

scholarly journals Residual stresses in thermite welded rails: significance of additional forging

2020 ◽  
Vol 64 (7) ◽  
pp. 1195-1212
Author(s):  
B. Lennart Josefson ◽  
R. Bisschop ◽  
M. Messaadi ◽  
J. Hantusch
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welding Process ◽  
Surface Zone ◽  
Fe Model ◽  
Uneven Surface ◽  
Residual Stress Field ◽  
High Dynamic

Abstract The aluminothermic welding (ATW) process is the most commonly used welding process for welding rails (track) in the field. The large amount of weld metal added in the ATW process may result in a wide uneven surface zone on the rail head, which may, in rare cases, lead to irregularities in wear and plastic deformation due to high dynamic wheel-rail forces as wheels pass. The present paper studies the introduction of additional forging to the ATW process, intended to reduce the width of the zone affected by the heat input, while not creating a more detrimental residual stress field. Simulations using a novel thermo-mechanical FE model of the ATW process show that addition of a forging pressure leads to a somewhat smaller width of the zone affected by heat. This is also found in a metallurgical examination, showing that this zone (weld metal and heat-affected zone) is fully pearlitic. Only marginal differences are found in the residual stress field when additional forging is applied. In both cases, large tensile residual stresses are found in the rail web at the weld. Additional forging may increase the risk of hot cracking due to an increase in plastic strains within the welded area.

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