Recent Developments in Experimental and Numerical Assessments of Welding-Induced Residual Stresses

2018 ◽  
Author(s):  
Bai-Qiao Chen ◽  
Marzieh Hashemzadeh ◽  
Yordan Garbatov ◽  
C. Guedes Soares
Keyword(s):  
Residual Stresses ◽  
Large Scale ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Welded Structures ◽  
Simulation Techniques ◽  
Numerical Assessment ◽  
Welding Sequence ◽  
Recent Developments ◽  
Inherent Deformation

The objective of this work is to present and review the recent developments in the experimental and numerical assessment and simulation techniques on the welding induced distortions and residual stresses. The temperature distribution, welding induced distortion and residual stresses in thin walled welded structures, originating from different experimental tests are reviewed and discussed. Different mathematical models and their numerical applications in representing the heat source are analysed and their advantages and drawbacks are discussed. Thermal stress analyses employing the three-dimensional nonlinear thermo-elasto-plastic approaches and finite element simulations with inherent deformation applicable to large-scale and complex welded structures are also revised and discussed. Discussions on the material properties of the base metal, heat affected zone (HAZ) and weld metal, the effect of the welding sequence, and the pattern of residual stress distribution presented are given a special attention.

scholarly journals Collisionless Dynamics and the Cosmic Web

2014 ◽  
Vol 11 (S308) ◽  
pp. 87-96
Author(s):  
Oliver Hahn
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Large Scale ◽  
Velocity Potential ◽  
Three Dimensional ◽  
Maximum Amount ◽  
Lagrangian Manifold ◽  
Linear Regime ◽  
Fine Grained ◽  
Simulation Techniques

AbstractI review the nature of three-dimensional collapse in the Zeldovich approximation, how it relates to the underlying nature of the three-dimensional Lagrangian manifold and naturally gives rise to a hierarchical structure formation scenario that progresses through collapse from voids to pancakes, filaments and then halos. I then discuss how variations of the Zeldovich approximation (based on the gravitational or the velocity potential) have been used to define classifications of the cosmic large-scale structure into dynamically distinct parts. Finally, I turn to recent efforts to devise new approaches relying on tessellations of the Lagrangian manifold to follow the fine-grained dynamics of the dark matter fluid into the highly non-linear regime and both extract the maximum amount of information from existing simulations as well as devise new simulation techniques for cold collisionless dynamics.

scholarly journals Prediction of Residual Stresses in a Multipass Pipe Weld by a Novel 3D Finite Element Approach

2018 ◽  
Author(s):  
Hui Huang ◽  
Jian Chen ◽  
Blair Carlson ◽  
Hui-Ping Wang ◽  
Paul Crooker ◽  
...  
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
High Performance ◽  
Large Scale ◽  
Graphics Processing Unit ◽  
Computational Cost ◽  
Three Dimensional ◽  
Processing Unit ◽  
Girth Welds ◽  
Welding Processes

Due to enormous computation cost, current residual stress simulation of multipass girth welds are mostly performed using two-dimensional (2D) axisymmetric models. The 2D model can only provide limited estimation on the residual stresses by assuming its axisymmetric distribution. In this study, a highly efficient thermal-mechanical finite element code for three dimensional (3D) model has been developed based on high performance Graphics Processing Unit (GPU) computers. Our code is further accelerated by considering the unique physics associated with welding processes that are characterized by steep temperature gradient and a moving arc heat source. It is capable of modeling large-scale welding problems that cannot be easily handled by the existing commercial simulation tools. To demonstrate the accuracy and efficiency, our code was compared with a commercial software by simulating a 3D multi-pass girth weld model with over 1 million elements. Our code achieved comparable solution accuracy with respect to the commercial one but with over 100 times saving on computational cost. Moreover, the three-dimensional analysis demonstrated more realistic stress distribution that is not axisymmetric in hoop direction.

scholarly journals FIRST ASSESSMENTS ON HERITAGE SCIENCE ORIENTED IMAGE-BASED MODELING USING LOW-COST MODIFIED AND MOBILE CAMERAS

2019 ◽  
Vol XLII-2/W17 ◽  
pp. 23-30 ◽  
Author(s):  
E. Adamopoulos ◽  
F. Rinaudo ◽  
A. Bovero
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Three Dimensional ◽  
Metric Properties ◽  
Scientific Investigations ◽  
Three Dimensional Modeling ◽  
Heritage Science ◽  
Thermal Cameras ◽  
Recent Developments ◽  
Good Quality Image

Abstract. Three-dimensional modeling of cultural heritage, especially concerning large scale studies, as for example, archaeometry, diagnostics and conservation intervention applications, which usually require high-resolution and multi-spectral analyses, necessitates the use of complicate and often expensive equipment. Recent developments regarding low-cost commercially available spectrally modified digital reflex cameras, smartphones with good quality image sensors, mobile thermal cameras in combination with automated or semi-automated photogrammetric software implementing Structure from Motion (SfM) and Multiview Stereo (MVS) algorithms constitute some cheaper and simpler alternatives. Although, the results of the integration of these types of sensors and techniques are often not evaluated as metric products. The presented research combines the above-mentioned instrumentation and software to implement and evaluate low-cost 3D modeling solutions on heritage science-oriented case studies, but also to perform some first assessments on the resulting models' metric properties, quality of texture and usefulness for further scientific investigations.

Design Support Tool for Prediction of Welding Distortion in Multiply Stiffened Plate Structures: Experimental and Computational Investigation

2005 ◽  
Vol 21 (04) ◽  
pp. 219-234
Author(s):  
Duncan Camilleri ◽  
Tugrul Comlekci ◽  
Thomas G. F. Gray
Keyword(s):  
Large Scale ◽  
Computational Models ◽  
Plane Deformation ◽  
Computational Prediction ◽  
Welding Distortion ◽  
Plate Structures ◽  
Welded Structures ◽  
Welding Sequence ◽  
Out Of Plane ◽  
Welding Processes

Many industries, such as shipbuilding, concerned with the fabrication of fusionwelded plate structures, face increasing challenges to produce lightweight structures. This design requirement is commonly met by using thin-plate, multiply stiffened, welded structures, but severe difficulties and high rectification costs are frequently incurred, related to the evolution of out-of-plane deformations. The overall scope of this study is to improve the applicability of computational prediction of distortion by providing simple and adaptable methodologies, which can be readily validated through experience of application in the industrial context. These methods are designed to be computationally economic and robust, and they are also generic with respect to material properties, welding processes, and thickness. The aim is to provide design engineers with the tools to explore alternative structural and process parameters and hence to find out if the outcomes will be acceptable, prior to embarking on manufacturing operations typical of large-scale welded structures. The validity of the simulations was investigated via full-scale tests where several filletwelded 100 mm × 6 mmstiffeners were attached to 4 m × 1.5 m × 5 mmthick plates, according to different sequences. The computational models were used to optimize the welding scheme with respect to minimum out-of-plane deformation and welding sequence.

Influence of Welding Conditions on Residual Stresses of Multi-Pass Tube Sheet Welds

2012 ◽  
Vol 525-526 ◽  
pp. 349-352
Author(s):  
Hong Li ◽  
Yong Zheng ◽  
Li Li
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Transient Temperature ◽  
Tube Sheet ◽  
Element Analysis ◽  
Time Dynamic ◽  
Welding Sequence ◽  
Welding Line

Residual stresses and residual plastic strains of the welded structures are the products of nonlinear behaviors during welding. The residual stresses will cause errors during the assembly of the structure and injure the beauty of appearance of the structure. Based on an elastic-plastic-model, finite element numerical simulation of a representative tube sheet penetration assembly with loop welding line joined by multi-pass welding is carried out and the influence of welding conditions on residual stresses of the tube sheet welds is studied in this paper. Nonlinear three dimensional transient temperature fields and real-time dynamic stresses field are analyzed by FEM. The heat source is modeled as a moving heat flux following a double ellipsoid distribution and the temperature-dependent properties of materials are considered. The method of birth and death of element in finite element analysis is applied to simulate the gradual growth of weld pass metal. It is shown that welding sequence, size of groove welding and weld toes dressing will obviously change the magnitude of the residual stresses of tube sheet welds.

scholarly journals Influence of Restraint Conditions on Welding Residual Stresses in H-Type Cracking Test Specimens

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2700 ◽  
Author(s):  
Jiamin Sun ◽  
Jonas Hensel ◽  
Thomas Nitschke-Pagel ◽  
Klaus Dilger
Keyword(s):  
Numerical Simulation ◽  
Tensile Stress ◽  
Residual Stresses ◽  
Experimental Method ◽  
Large Scale ◽  
Small Scale ◽  
Welded Structures ◽  
The Real ◽  
Restrained Cracking ◽  
Welding Processes

From the viewpoint of mechanics, weld cracking tends to occur if the induced tensile stress surpasses a certain value for the particular materials and the welding processes. Welding residual stresses (WRS) can be profoundly affected by the restraint conditions of the welded structures. For estimating the tendency of weld cracking, the small-scale H-type slit joints have been widely used for cracking tests. However, it is still hard to decide whether the real large-scale component can also be welded without cracking even though the tested weld cracking specimens on the laboratory scale can be welded without cracking. In this study, the intensity of restraint which quantitatively indicates how much a joint is restrained is used. The influence of restraint condition (intensity of restraint) on WRS is systematically investigated using both the numerical simulation and the experimental method. The achievement obtained in the current work is very beneficial to design effective H-type self-restrained cracking test specimens for evaluating the sensitivity of the material and the welding procedures for weld cracking in the real large-scale components.

Computational methods and experimental validation of welding distortion models

2007 ◽  
Vol 221 (4) ◽  
pp. 235-249 ◽  
Author(s):  
D Camilleri ◽  
P Mollicone ◽  
T G F Gray
Keyword(s):  
Experimental Study ◽  
Residual Stresses ◽  
Thin Plate ◽  
Computational Methods ◽  
Experimental Validation ◽  
Experimental Tests ◽  
Welding Distortion ◽  
Computationally Efficient ◽  
Welded Structures ◽  
Out Of Plane

Multiply-stiffened, thin plate, welded fabrications are used in a wide variety of transport fields, however the resulting out-of-plane distortion associated with welding exacts a severe design penalty. Depending on the information required, the size of the structure under investigation and the computer power at hand, three computational strategies may be considered to predict welding distortion. If prediction of the localized residual stresses from welding is of major importance, then a full transient, uncoupled thermo-elastoplastic analysis is preferred. This method is not readily applicable to predict welding distortions in industrial-scale welded structures. More computationally efficient models are required and two other models are suggested in the current study. A series of experimental tests of a realistic nature were performed to validate the proposed computational strategies. Computational and experimental study of butt and fillet welding of small and industrial size fabrications is considered.

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