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1
AbuShanab, Waheed, and Essam Moustafa. "Detection of Friction Stir Welding Defects of AA1060 Aluminum Alloy Using Specific Damping Capacity." Materials 11, no. 12 (November 30, 2018): 2437. http://dx.doi.org/10.3390/ma11122437.
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The demand for nondestructive testing has increased, especially in welding testing. In the current study, AA1060 aluminum plates were jointed using the friction stir welding (FSW) process. The fabricated joints were subjected to free vibration impact testing in order to investigate the dynamic properties of the welded joint. Damping capacity and dynamic modulus were used in the new prediction method to detect FSW defects. The data acquired were processed and analyzed using a dynamic pulse analyzer lab shop and ME’Scope’s post-processing software, respectively. A finite element analysis using ANSYS software was conducted on different types of designed defects to predict the natural frequency. The results revealed that defective welded joints significantly affect the specific damping capacity. As the damping ratio increased, so did the indication of opportunities to increase the presence of defects. The finite element simulation model was consistent with experimental work. It was therefore revealed that natural frequency was insufficient to predict smaller defects.
2
Konjatić, Pejo, Dražan Kozak, and Nenad Gubeljak. "The Influence of the Weld Width on Fracture Behaviour of the Heterogeneous Welded Joint." Key Engineering Materials 488-489 (September 2011): 367–70. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.367.
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Since welded constructions are widely used in engineering, a certain flaws in welded joints may occur either in process of welding or in exploitation period. Easiest way to prolong working life of such welded construction is to repair welded joint to eliminate possibility of construction failure. Process of repair welding usually gives heterogeneous welded joints because during process of repair additional material is introduced into welded joint, resulting in heterogeneity from the presence of materials in welded joint point of view. Such difference in materials usually results in yield strength difference between materials, represented with mismatch ratio, and it is commonly present in welds where high strength low-alloyed (HSLA) steels were welded. Since I butt welded joints are very common in welding, a systematic investigation of such welds is performed and presented in this paper. Therefore in this investigation the influence of present material in heterogeneous weld and geometry of weld is investigated in context of fracture resistance of welded joint represented as yield load solutions in the first place. A flaw in form of crack was implemented in such heterogeneous weld and using finite element method yield load solutions for different combinations of weld geometry and material strength are obtained and presented in form of diagrams.
3
Reddy Vempati, Srinivasa, K. Brahma Raju, and K. Venkata Subbaiah. "Simulation of Ti-6Al-4V cruciform welded joints subjected to fatigue load using XFEM." Journal of Mechanical Engineering and Sciences 13, no. 3 (September 27, 2019): 5371–89. http://dx.doi.org/10.15282/jmes.13.3.2019.11.0437.
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The stress distribution of cruciform shape welded joints is analyzed by finite element codes ABAQUS. Welded joints with various weld shapes and sizes are investigated to estimate the fatigue life of different joints. The fatigue behavior is evaluated under constant amplitude loading (R=0.1). The aim of this work is fatigue behavior evaluation of fillet welded cruciform joint for different weld geometry. The weld geometry are considered: concave, convex and flat weld shape of different weld sizes. The stress intensity factor (SIF) of a TI 6AL4V, is calculated by using Extended finite element method (XFEM) in ABAQUS software. Simulations of fatigue life for different weld shapes at different stresses are analyzed and crack initiations are identified the number of severe fatigue life cycles which are obtained are very close to the theoretical values. In present study the importance of XEFM method is recognized to predict the crack growth rate for convex specimen which is subjected maximum fatigue stress.
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Shiraiwa, Takayuki, Fabien Briffod, and Manabu Enoki. "Fatigue Life Prediction of Welded Joint by Microstructure-based Simulation." MATEC Web of Conferences 269 (2019): 03005. http://dx.doi.org/10.1051/matecconf/201926903005.
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This paper proposes a numerical framework to predict fatigue life on welded joints by integrating several computational techniques. The framework consists of five steps: i) materials properties estimation; ii) welding simulation using thermo-mechanical finite element method; iii) macroscopic stress field analysis under cyclic loading; iv) mesoscopic stress field analysis using crystal plasticity finite element method (CPFEM); v) analysis of fatigue crack growth. The total number of cycles to failure is eventually obtained by the sum of initiation life calculated by CPFEM and propagation life calculated by X-FEM. A fatigue life of butt joint is evaluated by the proposed method. The results demonstrated the possibility of evaluating the fatigue life and its scattering by the proposed framework.
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Corigliano, Pasqualino. "Non-linear finite element analysis of a Ti6Al4V/Inconel 625 joint obtained by explosion welding for sub-sea applications." Underwater Technology 38, no. 1 (March 30, 2021): 13–16. http://dx.doi.org/10.3723/ut.38.013.
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Industries have shown interest in the use of dissimilar metals to make corrosion-resistant materials combined with good mechanical properties in marine environments. Explosive welding can be considered a good method for joining dissimilar materials to prevent galvanic corrosion. The aim of the present study was to simulate the non-linear behaviour of a Ti6Al4V/Inconel 625 welded joint obtained by explosion welding from the values of the tensile ultimate strength and yielding strength of the parent materials. The present study compared the stress-strain curve from tensile loading obtained by the non-linear finite element analysis with the experimental stress-strain curve of a bimetallic joint. The applied method provides useful information for the development of models and the prediction of the structural behaviour of Ti6Al4V/Inconel 625 explosive welded joints.
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Xu, Di, and Xiang Ling. "Numerical Simulation of Residual Stress in the Glass-to-Metal Diffusion Seals." Materials Science Forum 575-578 (April 2008): 666–71. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.666.
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The glass-to-metal seals are widely used in the solar thermal power. When a glass-to-metal seal is cooled in the process of diffusion welding, the residual stresses are generated due to different thermal contraction between the two materials. The residual stresses built up along the interface near the end of the seal can induce welded joints to crack and decrease the fatigue intensity of the welded joints and thus are of technical importance. In order to obtain the residual stresses existed in the diffusion welded joints, the glass-to-metal vacuum diffusion sealing process were simulated by using finite element software ABAQUS. Furthermore, the influences of temperature, time, vacuum, and seal pressure on the strength of the glass-to-metal diffusion welding were analyzed. The optimization of the diffusion welding process parameter based on the simulation of the residual stress and analysis of the micro-structure and the macro-mechanical performance of the diffusion welded seals was carried out. The distribution of residual stress on the surface of the glass-to-metal joint caused by welding is measured by X-ray diffraction method, and compared with the result of the numerical simulation to prove the validation of the finite element model.
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Xue, He, Yueqi Bi, Shuai Wang, Jianlong Zhang, and Siyu Gou. "Compilation and Application of UMAT for Mechanical Properties of Heterogeneous Metal Welded Joints in Nuclear Power Materials." Advances in Materials Science and Engineering 2019 (November 22, 2019): 1–12. http://dx.doi.org/10.1155/2019/3151823.
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For the problem of mechanical properties of heterogeneous dissimilar metal welded joints, when analyzed by the finite element method, it is usually simplified into a “sandwich” material structure model. However, the mechanical properties of materials in different regions of the “sandwich” material mechanics model are different, and there will be mutations at the material interface. In order to accurately describe the mechanical properties of welded joints, the constitutive equations of dissimilar metal welded joint materials were compiled, and the constitutive equations of inhomogeneous materials whose material mechanical properties were continuously changed with space coordinates were established. The ABAQUS software was used to establish the “sandwich” model and the continuous transition model. The model is used to compare and analyze the crack tip stress distribution of different yield strength mismatch coefficients. The results show that the continuous transition material model eliminates the mutation of the “sandwich” model at the material interface and achieves the continuous change of the mechanical properties of the material. For the longitudinal crack, under the influence of different mismatch coefficients, the crack tip stress field of the transitional material model is deflected toward the low yield strength side. The compilation of constitutive equations for continuous transition materials of dissimilar metal welded joints provides a basis for the safety evaluation of dissimilar metal welded joints.
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Yousefi, Armin, Ahmad Serjouei, Reza Hedayati, and Mahdi Bodaghi. "Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys." Materials 14, no. 9 (April 23, 2021): 2171. http://dx.doi.org/10.3390/ma14092171.
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In the present study, the fatigue behavior and tensile strength of A6061-T4 aluminum alloy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agreement was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.
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Mochizuki, M., M. Hayashi, and T. Hattori. "Residual Stress Analysis by Simplified Inherent Strain at Welded Pipe Junctures in a Pressure Vessel." Journal of Pressure Vessel Technology 121, no. 4 (November 1, 1999): 353–57. http://dx.doi.org/10.1115/1.2883714.
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We present a new and simplified method of estimating residual stress in welded structures by using inherent strain. The method makes use of elastic analysis by means of the finite element method and is used to calculate the residual stress in complicated three-dimensional structures efficiently. The inherent strain distribution in a welded joint of a small-diameter pipe penetrating a pressure vessel was assumed to be a simple distribution, and the residual stress was calculated. Inherent strain distributions were inferred from those of welded joints with simple shapes. The estimated residual stress using these inferred inherent strains agrees well with the measurements of a mock-up specimen. The proposed method is a simple way to estimate welding residual stress in three-dimensional structures of complicated shapes.
10
Sedmak, Simon A., Aleksandar Sedmak, Aleksandar Grbović, and Zoran Radaković. "Integrity and Life Assessment of Welded Joints Made of Micro-Alloyed High Strength Steels." Advanced Materials Research 1157 (February 2020): 161–67. http://dx.doi.org/10.4028/www.scientific.net/amr.1157.161.
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Structural integrity and life of welded joints made of a micro-alloyed low-carbon fine-grained normalised high strength pressure vessel steel, P460NL1 is presented [1]. The researach performed within the scope of this topic involved a large number of experiments, including tensile and bending tests, hardness and toughness, as well as metallography and fractography tests, in order to determine the mechanical properties of the materials and the welded joints in detail, along with their microstructures and their influence on the obtained test results. Specimens cut out of a welded plate with dimensions of 500x500x14 mm were used for the experiments, whereas certain tests required the making of notches in the specimens, inside the heat affected zone, and this welded joint region was the focus of the research. Fatigue experimental tests were based on the assumption that fatigue crack growth rate changes depending on the regions through which the crack passed during its propagation. For this purpose, specimens used in toughness and fatigue tests were divided into four groups, depending on the part of the plate from which they were taken. Numerical calculations were performed using the extended finite element method (XFEM) [2]. Simulations were based on the experimentally determined values of Paris law coefficients, C i m [3-5], for every region through which the crack propagated during each test. Obtained results have indicated good agreement with the experimental ones, which verified the application of extended finite element method in this case.
11
Moskvichev, Egor. "Distribution of material properties in finite element models of inhomogeneous elements of structures." EPJ Web of Conferences 221 (2019): 01034. http://dx.doi.org/10.1051/epjconf/201922101034.
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This paper discusses an approach to finite element modelling of structure elements considering material inhomogeneity. This approach is based on the functional dependence of mechanical properties on the spatial coordinates of finite elements. It allows modelling gradient transitions between different materials, which avoid stress discontinuities during strength analysis. The finite element models of cold formed angle, welded joint and thermal barrier coating, created by this method, have been presented.
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Randić, Miroslav, Duško Pavletić, and Marko Fabić. "Evaluation of the Stress Concentration Factor in Butt Welded Joints: A Comparative Study." Metals 11, no. 3 (March 3, 2021): 411. http://dx.doi.org/10.3390/met11030411.
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Surface cracks in butt-welded joints usually occur in places with increased stress concentrations. The stress concentration factor (SCF) can be calculated using an empirical equation, with five geometric parameters of a butt-welded joint (thickness of the base material, toe radius, weld toe angle, weld width, and reinforcement height). However, in an industrial environment, it is impractical and sometimes even impossible to measure all five geometric parameters with sufficient accuracy. In this study, eight experiments on butt-welded joints were performed. All samples were scanned with a 3D scanner, and the geometric sizes of the welded joints were measured using computer software. A modified empirical expression proposed by Ushirokawa and Nakayama was used to calculate the SCF; the expression was adjusted in such a way that the SCF was calculated by knowing only the toe radius. In addition, four new expressions were proposed for the calculation of the SCF by knowing the toe radius in relation to the weld toe angle; the expressions were then compared and analyzed. Additionally, the values of the stress concentrations in the butt-welded joints were obtained using a finite element method (FEM). The SCFs calculated using the four methods were compared and further discussed. Our data suggested a new accurate and straightforward approach for calculating the SCF by knowing only the weld toe radius.
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Molski, Krzysztof L., Piotr Tarasiuk, and Grzegorz Glinka. "Stress concentration at cruciform welded joints under axial and bending loading modes." Welding in the World 64, no. 11 (August 12, 2020): 1867–76. http://dx.doi.org/10.1007/s40194-020-00966-4.
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Abstract The paper is concerned with the problem of stress concentration in cruciform fillet welded joints subjected to axial and bending load. Extended numerical analyses were carried out with the help of the finite element method. It made it possible to estimate stress concentration factors Kt for a variety of geometrical parameters defining the geometry of cruciform welded joints. It has been found that approximate Kt formulas, available in the literature, have two disadvantages, i.e. an unknown accuracy and small range of application with respect to geometrical parameters defining the weld shape. For these reasons, more general and accurate new formulas for stress concentration factors Kt have been derived. Even though the present approach is applicable to all types of welded joints, the analysis presented below has been conducted for a cruciform joint with the weld flank angle of θ = 45°. Final solutions have been given in the form of polynomial expressions, and they can be easily used in computer-aided design procedures.
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Han, Min Koo, and Mamidala Ramulu. "Fatigue Life Prediction of Ship Welded Materials." Key Engineering Materials 297-300 (November 2005): 743–49. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.743.
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Fatigue crack propagation life of weld toe crack through residual stress field was estimated using Elber's crack closure concept. Propagation of weld toe crack is heavily influenced by residual stresses caused by the welding process, so it is essential to take into account the effect of residual stresses on the propagation life of a weld toe crack. Fatigue cracks at transverse and longitudinal weld toe was studied, these two cases represent the typical weld joints in ship structures. Numerical and experimental studies are performed for both cases. Residual stresses near the welding area were estimated through a nonlinear thermo-elasto-plastic finite element method and the residual stress intensity factor with Glinka's weight function method. Effective stress intensity factor was calculated using the Newman-Forman-de Koning-Henriksen equation, which is based on the Dugdale strip yield model in estimating the crack closure level, U, at different stress ratios. Calculated crack propagation life coincided well with experimental results.
15
Liang, Bin, Jian Ming Gong, Hai Tao Wang, and Cheng Ye. "Evaluation of Residual Stresses in Butt-Welded Joints by Residual Magnetic Field Measurements." Applied Mechanics and Materials 217-219 (November 2012): 2427–34. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.2427.
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Measuring residual stray field (RMF) signals provides a promising tool to analyze the stress in ferromagnetic welded materials. In this paper, the variations of the normal component of the RMF, Hp(y), perpendicular to welded seam are measured. The finite element method is used to model residual stress in the specimen. The influence of residual stress on the Hp(y) component is shown. It is found that the distributions of the Hp(y) component are described by a Boltzmann fitting curve, show a good qualitative correlation with residual stress. A quantitative method for the evaluation of residual stress in ferromagnetic steels based on the gradient of the Hp(y) component and equivalent (vonMises) stress is presented.
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Xue, He, Zheng Wang, Shuai Wang, Jinxuan He, and Hongliang Yang. "Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints." Materials 14, no. 15 (July 26, 2021): 4145. http://dx.doi.org/10.3390/ma14154145.
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Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.
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Campagnolo, Alberto, Paolo Ferro, Luca Romanin, and Giovanni Meneghetti. "Residual Notch Stress Intensity Factors in Welded Joints Evaluated by 3D Numerical Simulations of Arc Welding Processes." Materials 14, no. 4 (February 8, 2021): 812. http://dx.doi.org/10.3390/ma14040812.
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Approaches based on calculating Residual Notch Stress Intensity Factors (R-NSIFs) assume the weld toe to be a sharp V-notch that gives rise to a residual singular stress distribution close to the weld toe. Once R-NSIFs are determined, they might be included in local fatigue criteria for the structural strength assessment of welded joints based on NSIFs due to external cyclic loading. However, the numerical calculation of R-NSIFs through finite element (FE) simulations of the welding process requires extremely refined meshes to properly capture the residual stress singularity. In this context, the Peak Stress Method (PSM) has recently been adopted to estimate R-NSIFs due to residual stresses by means of coarse meshes of 2D 4-node plane or 3D 8-node brick elements. The aim of this work is to investigate the applicability of the PSM to estimate R-NSIFs in a butt-welded joint using coarse meshes of 3D 10-node tetra elements. The R-NSIF distribution at the weld toe line is estimated by applying the PSM to coarse meshes of 3D 10-node tetra elements, and the results are in agreement with those obtained using 3D 8-node brick elements. Accordingly, the PSM based on tetra elements further enhances the rapid estimation of R-NSIFs using coarse meshes and could be effective in analyzing complex 3D joint geometries.
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Zanetti, Michele, Vittorio Babini, and Giovanni Meneghetti. "Fat classes of welded steel details derived from the master design curve of the peak stress method." Welding in the World 65, no. 4 (March 2, 2021): 653–65. http://dx.doi.org/10.1007/s40194-020-01057-0.
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AbstractIn this paper, the peak stress method (PSM) is adopted to analyse the fatigue strength of steel welded joints. According to this method, a single design curve is expressed in terms of a properly defined equivalent peak stress and it is valid for fatigue design of arc-welded steel joints. Private companies often need simple finite element beam models for fatigue strength assessments, because of the large dimensions of the structures. However, beam elements provide nominal stresses (and not local stresses) that must be compared with appropriate fatigue strength values (the FAT classes) available in design standards. Due to the limited number of FAT classes available, finding the appropriate one is frequently troublesome, particularly when complex geometries are considered. The objective of this work is to define FAT classes in terms of nominal stress for a number of geometrically complex structural details, starting from the design curve of the PSM. FAT classes have also been determined using the hot spot stress approach. Then the results obtained with the two methods are compared. The structural details analysed in the present paper are typically adopted in amusement park structures and are not classified in common design standards.
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Molski, Krzysztof L., and Piotr Tarasiuk. "Stress Concentration Factors for Welded Plate T-Joints Subjected to Tensile, Bending and Shearing Loads." Materials 14, no. 3 (January 24, 2021): 546. http://dx.doi.org/10.3390/ma14030546.
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The paper deals with the problem of stress concentration at the weld toe of a plate T-joint subjected to axial, bending, and shearing loading modes. Theoretical stress concentration factors were obtained from numerical simulations using the finite element method for several thousand geometrical cases, where five of the most important geometrical parameters of the joint were considered to be independent variables. For each loading mode—axial, bending, and shearing—highly accurate closed form parametric expression has been derived with a maximum percentage error lower than 2% with respect to the numerical values. Validity of each approximating formula covers the range of dimensional proportions of welded plate T-joints used in engineering applications. Two limiting cases are also included in the solutions—when the weld toe radius tends to zero and the main plate thickness becomes infinite.
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Marin, T., and G. Nicoletto. "Fatigue design of welded joints using the finite element method and the 2007 ASME Div. 2 Master curve." Frattura ed Integrità Strutturale 3, no. 9 (July 1, 2009): 76–84. http://dx.doi.org/10.3221/igf-esis.09.08.
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Riad, Brahami, Hamri Okba, and Sfarni Samir. "Fatigue life assessment of welded joints in a crane boom using different structural stress approaches." Journal of Mechanical Engineering and Sciences 13, no. 2 (June 28, 2019): 5048–73. http://dx.doi.org/10.15282/jmes.13.2.2019.20.0417.
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This article presents a study of the fatigue strength of welded parts in a crane boom. First, a finite element analysis was carried out over the whole structure. Two critical welded zones were identified and a detailed analysis was carried on them, in the form of sub-models. Three different approaches for estimating the structural stress in welded zones, were presented and applied to each sub-model. Results were compared and discussed. The evaluation of fatigue resistance by the use of appropriate S-N curves for each method was also carried out and discussed. The use of these approaches on a complex industrial structure, and on tubular joints with hollow sections required to perform many adaptations and to solve several difficulties presented hereafter.
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Wang, Gaoxin, Youliang Ding, Zhijun Liu, and Jingshu Shao. "Method of Calculating Life-Cycle Fatigue Damage of Orthotropic Steel Bridge Decks under the Combined Actions of Vehicle Loads and Pavement Temperature." Shock and Vibration 2020 (November 4, 2020): 1–10. http://dx.doi.org/10.1155/2020/6429034.
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The fatigue analysis on orthotropic steel bridge decks is a hot topic in bridge engineering field. This study provides one method for fatigue analysis under the combined actions of vehicle loads and pavement temperature. To be specific, taking the steel bridge deck of one cable-stayed bridge as a research object, this study proposes a method of calculating life-cycle fatigue damage of orthotropic steel deck under the combined actions of vehicle loads and pavement temperature. First, a finite element model of steel bridge deck with asphalt pavement is built to analyze the influence of pavement temperature on the fatigue stress of steel bridge deck. Second, a simulation method of fatigue stress caused by random vehicle loads is proposed. Finally, a method of calculating the life-cycle fatigue damage of welded joints under the combined actions of vehicle loads and temperature is proposed. The results show that temperature has a significant effect on fatigue damage, and the cumulative fatigue damage in the rib-to-rib welded joint is significantly greater than that in the deck-to-rib welded joint. The results can provide meaningful references for bridge engineers to carry out fatigue analysis on orthotropic steel bridge decks.
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Milošević, Nenad Zoran, Aleksandar Stojan Sedmak, Gordana Miodrag Bakić, Vukić Lazić, Miloš Milošević, Goran Mladenović, and Aleksandar Maslarević. "Determination of the Actual Stress–Strain Diagram for Undermatching Welded Joint Using DIC and FEM." Materials 14, no. 16 (August 20, 2021): 4691. http://dx.doi.org/10.3390/ma14164691.
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This paper presents new methodology for determining the actual stress–strain diagram based on analytical equations, in combination with numerical and experimental data. The first step was to use the 3D digital image correlation (DIC) to estimate true stress–strain diagram by replacing common analytical expression for contraction with measured values. Next step was to estimate the stress concentration by using a new methodology, based on recently introduced analytical expressions and numerical verification by the finite element method (FEM), to obtain actual stress–strain diagrams, as named in this paper. The essence of new methodology is to introduce stress concentration factor into the procedure of actual stress evaluation. New methodology is then applied to determine actual stress–strain diagrams for two undermatched welded joints with different rectangular cross-section and groove shapes, made of martensitic steels X10 CrMoVNb 9-1 and Armox 500T. Results indicated that new methodology is a general one, since it is not dependent on welded joint material and geometry.
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Wiechmann, Philipp, Hannes Panwitt, Horst Heyer, Michael Reich, Manuela Sander, and Olaf Kessler. "Combined Calorimetry, Thermo-Mechanical Analysis and Tensile Test on Welded EN AW-6082 Joints." Materials 11, no. 8 (August 9, 2018): 1396. http://dx.doi.org/10.3390/ma11081396.
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Wide softening zones are typical for welded joints of age hardened aluminium alloys. In this study, the microstructure evolution and distribution of mechanical properties resulting from welding processes of the aluminium alloy EN AW-6082 (AlSi1MgMn) was analysed by both in-situ and ex-situ investigations. The in-situ thermal analyses included differential scanning calorimetry (DSC), which was used to characterise the dissolution and precipitation behaviour in the heat affected zone (HAZ) of welded joints. Thermo-mechanical analysis (TMA) by means of compression tests was used to determine the mechanical properties of various states of the microstructure after the welding heat input. The necessary temperature–time courses in the HAZ for these methods were measured using thermocouples during welding. Additionally, ex-situ tensile tests were done both on specimens from the fusion zone and on welded joints, and their in-depth analysis with digital image correlation (DIC) accompanied by finite element simulations serve for the description of flow curves in different areas of the weld. The combination of these methods and the discussion of their results make an essential contribution to understand the influence of welding heat on the material properties, particularly on the softening behaviour. Furthermore, the distributed strength characteristic of the welded connections is required for an applicable estimation of the load-bearing capacity of welded aluminium structures by numerical methods.
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Nakacho, K., and Y. Ueda. "A Simple Estimating Method for Reduction of Welding Residual Stresses in Thick Welded Joint From Stress-Relief Annealing—Part II: The Characteristics of Reduction of Welding Residual Stresses in Very Thick Joints During SR Treatment." Journal of Pressure Vessel Technology 121, no. 1 (February 1, 1999): 11–16. http://dx.doi.org/10.1115/1.2883659.
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Stress-relief annealing (SR treatment) is often applied to relieve welding residual stresses in the fabrication process of pressure vessels, etc. This study aims at development of an efficient method as simple as hand calculation to estimate reduction of residual stresses of very thick welded joint by SR treatment. In the first report, an estimating method was developed for relaxation tests, in uniaxial stress state, at changing and constant temperatures because the stress relaxation phenomenon is considerably similar to that observed in the SR treatment of a joint. In this report, the stresses relaxed by SR treatment in a very thick welded joint are analyzed accurately by the finite element method based on thermal elastic-plastic-creep theory. The characteristics of the changes of the welding residual stresses in multiaxial stress state are studied in detail for further development of the estimating method to SR treatment of a very thick welded joint, of which the stress state and boundary condition are very complex.
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Kik, Tomasz, Jaromír Moravec, and Martin Švec. "Experiments and Numerical Simulations of the Annealing Temperature Influence on the Residual Stresses Level in S700MC Steel Welded Elements." Materials 13, no. 22 (November 22, 2020): 5289. http://dx.doi.org/10.3390/ma13225289.
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The article presents the results of research on the influence of temperature and time changes of the annealing process on the values and distribution of stresses in the simulated heat-affected zone of S700MC steel welded joints. For this purpose, tests were carried out on a thermal cycle simulator, as well as heating the prepared samples in accordance with the recorded welding thermal cycles, and then annealing at temperatures from 200 to 550 °C. The stresses values in the tested samples before and after the annealing process were measured by using X-ray diffraction (XRD). The performed tests were verified with the results of numerical analyses using the finite element method (FEM) performed in the VisualWeld (SYSWELD) environment as, on the one hand, the verification of the obtained results, and, on the other hand, the source of data for the development of a methodology for conducting analyses of heat treatment processes of S700MC steel welded structures. Also presented are three examples of numerical analyses for Gas Metal Arc (GMAW), laser and hybrid welding and then the annealing process of the obtained joints at selected temperatures. The main purpose of the work was to broaden the knowledge on the influence of annealing parameters on the values and distribution of stresses in welded joints, but also to signal the possibility of using modern software in engineering practice.
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Fueki, Ryutaro, and Koji Takahashi. "Prediction of fatigue limit improvement in needle peened welded joints containing crack-like defects." International Journal of Structural Integrity 9, no. 1 (February 5, 2018): 50–64. http://dx.doi.org/10.1108/ijsi-03-2017-0019.
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Purpose The purpose of this paper is to estimate the acceptable defect size amax after needle peening (NP) and predict the fatigue limit improvement through the use of NP for an austenitic stainless steel welded joint containing an artificial semi-circular slit on a weld toe. Design/methodology/approach Residual stress and hardness distribution were measured. Microstructures around the weld toe were observed to clarify the cause for the change in hardness after NP. Finite element method analysis was used to analyze the change in the stress concentration following NP. Fracture mechanics was used to evaluate amax after NP. The fatigue limits before and after NP were predicted by determining amax for several levels of stress amplitude. Findings The tensile residual stress induced at the surface of the weld toe prior to NP changed to a compressive residual stress after NP. The residual stress near the surface layer after NP exceeded the yield stress prior to NP due to the increase in yield stress as a result of work hardening as well as the generation of a deformation-induced martensitic structure. The stress concentration was reduced due to the shape improvement caused by NP. The estimation value of amax after NP and the prediction results of fatigue limits were in good agreement with the fatigue test results. Practical implications The proposed method is useful in improving the reliability of welded joints used in large steel structures, transportation equipments and industrial machines. Originality/value From an engineering perspective, it is essential to estimate amax and the fatigue limit of welded joints with crack-like defects. However, it is unclear as to whether it is possible to predict amax and the effects of NP on the fatigue limit for stainless steel welded joints.
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Molski, Krzysztof L., and Piotr Tarasiuk. "Stress Concentration Factors for Butt-Welded Plates Subjected to Tensile, Bending and Shearing Loads." Materials 13, no. 8 (April 11, 2020): 1798. http://dx.doi.org/10.3390/ma13081798.
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This paper deals with the analysis of stress concentration at the weld toe of a Double-V and a Single-V butt-welded joints subjected to tensile, bending and shearing loads. For each geometrical and loading case accurate close form stress concentration factor formula based on more than 3.3 thousand finite element method solutions were obtained. The percentage error of the formulas is lower than 2.5% for a wide range of values of geometrical parameters including weld toe radius, weld width, plate thickness and weld toe angle. The limiting case, in which the weld toe radius tends to zero is also considered. In the cases of shearing loads, a plane model based on thermal analogy was developed. The whole analysis was performed assuming that a circular arc represents the shape of the excess weld metal. Presented solutions may be used in computer aided fatigue assessment of structural elements.
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Mladenovic, Sasa, Vera Sijacki-Zeravcic, Gordana Bakic, Jasmina Lozanovic-Sajic, Marko Rakin, Andrijana Djurdjevic, and Milos Djukic. "Numerical analysis of thermal stresses in welded joint smade of steels X20 and X22." Thermal Science 18, suppl.1 (2014): 121–26. http://dx.doi.org/10.2298/tsci131211178m.
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Stress calculation of steam pipeline is presented, focused on the welded joint. Numerical calculation was performed using the finite element method to obtain stress distribution in the welded joint made while replacing the valve chamber. Dissimilar materials were used, namely steel 10CrMoV9-10 according to EN 10216-2 for the valve chamber, the rest of steam pipeline was steel X20, whereas the transition piece material was steel X22. Residual stresses were calculated, in addition to design stresses, indicating critical regions and necessity for post-weld heat treatment.
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Yang, Fu-qiang, He Xue, Ling-yan Zhao, and Xiu-rong Fang. "Effects of Welded Mechanical Heterogeneity on Interface Crack Propagation in Dissimilar Weld Joints." Advances in Materials Science and Engineering 2019 (February 3, 2019): 1–10. http://dx.doi.org/10.1155/2019/6593982.
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The stress and strain status associated with the material properties is one of the main factors affecting stress corrosion cracking (SCC) of structural components in nuclear power plants (NPPs). In many SCC prediction models, the stress intensity factor calculated with homogeneous materials is used to characterize the crack tip stress state. However, the mechanical and material properties in weld joints are heterogeneous, which will produce the discontinuous distribution of stress and strain nearby crack tip and affect the crack propagation. To understand the material mechanical heterogeneity effects on interface crack propagation, the specimens with ultimate tensile strength mismatch and elastic modulus mismatch were studied by using an extended finite element method (XFEM). The results indicate that the interface crack extension is easy to occur in the specimens with larger ultimate tensile strength mismatch, while the elastic modulus mismatch has little effects on crack extension. The different interface cracks in the dissimilar metal weld joints of the reactor pressure vessel used in NPPs tend to deviate from the initial direction into alloy 182, and the interface crack propagation path fluctuation is small.
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Rusiński, Eugeniusz, Przemysław Moczko, and Paweł Kaczyński. "Structural Modifications of Excavator’s Bucket Wheel by the Use of Numerical Methods." Solid State Phenomena 165 (June 2010): 330–35. http://dx.doi.org/10.4028/www.scientific.net/ssp.165.330.
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In this paper the character of loads exerted on bucket wheel was evaluated. The places of maximal stresses were determined by using finite element analysis. After this operation, a new wheel hub design was initiated. The first phase was related to development of new conceptions of the hub. The proposed conceptions were rated with respect to mass and total length of welds. This procedure led to selection of the most suitable design, which was optimized in order to minimize stress. The work at this stage consisted of continuous modification of the geometrical form, meshing of finite element model and structural analysis thereby providing information about stresses and deformations. The workmanship of the structural component and welded joints were defined according to DIN 22261 2:2006 standard.
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Shi, L., SA Alexandratos, and NP O’Dowd. "Combined finite element and phase field method for simulation of austenite grain growth in the heat-affected zone of a martensitic steel weld." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, no. 1 (January 17, 2018): 13–27. http://dx.doi.org/10.1177/1464420717750999.
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Engineering components operating at high temperature often fail due to the initiation and growth of cracks in the heat-affected zone adjacent to a weld. Understanding the effects of microstructural evolution in the heat-affected zone is important in order to predict and control the final properties of welded joints. This study presents a combined finite element method and phase field method for simulation of austenite grain growth in the heat-affected zone of a tempered martensite (P91) steel weld. The finite element method is used to determine the thermal history of the heat-affected zone during gas tungsten arc welding of a P91 steel plate. Then, the calculated thermal history is included in a phase field model to simulate grain growth at various positions in the heat-affected zone. The predicted mean grain size and grain distribution match well with experimental data for simulated welds from the literature. The work lays the foundation for optimising the process parameters in welding of P91 and other ferritic/martensitic steels in order to control the final heat-affected zone microstructure.
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Sapozhnikov, S. B., M. A. Ivanov, and I. A. Shcherbakov. "The Ultimate Load Estimation of Welded Joints of High-Strength Steels subject to Mechanical and Geometric Heterogeneity." PNRPU Mechanics Bulletin, no. 1 (December 15, 2020): 99–108. http://dx.doi.org/10.15593/perm.mech/2020.1.08.
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In this paper we consider the problems arising in the numerical estimation of the ultimate load of welded joints of high-strength steels with slight hardening. The stress concentrator in the transition node from the deposited to the base metal is modeled based on the example of welding a roller wire on a plate made of high-strength steel. The use of welding wire with a yield point lower than that of the base metal allowed to simulate areas of the welded joint with heterogeneous mechanical properties. The geometry of three areas of the welded joint is studied, i.e. weld metal, heat-affected zone (HAZ) and the base metal. Mechanical properties of all three areas are determined by calculation and experimentally. For this purpose, it is proposed to consider the material in all sections as ideally elastic-plastic, and the yield strength is uniquely associated with the hardness in the indentation zone (a Rockwell diamond cone is used). Calculations of the inelastic indentation process by the finite element method (FEM) in axis-symmetric formulation allowed obtaining a linear relationship between the hardness and the yield strength with a coefficient of 0.418. Tests at a quasi-static three-point bend (with stretching in the surfacing area) were carried out on sample beams cut perpendicular to the direction of welding. The “force-deflection” diagrams are obtained and compared with the calculated curves (FEM in a three-dimensional formulation with an explicit consideration of the complex configuration of all sections and different yield stress in the areas determined by local hardness values). There is a good agreement between the calculated and experimental ultimate loads. The proposed method of the three-stage study (determination of local hardness, yield strength in the areas and the ultimate load) can be effectively used to assess the ultimate loads of the welded joints due to the low parametricity of the proposed models of materials inelastic deformation in areas for which it is impossible to manufacture standard samples for the study of mechanical properties. The experimental study of the strengthening effect of the seam with a stress concentrator in the form of an angle of 90 degrees on the value of the ultimate bending load showed that the removal of the deposited metal does not lead to an increase in the ultimate load of the welded joint when using the welding wire of low-carbon high-plastic steel.
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Lyudmirsky, Y. G., А. N. Soloviev, М. V. Soltovets, R. R. Kotlyshev, I. V. Mironov, and А. V. Kramskoy. "Technology and equipment for friction stir preweld edge preparation." Advanced Engineering Research 21, no. 2 (July 9, 2021): 163–70. http://dx.doi.org/10.23947/2687-1653-2021-21-2-163-170.
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Introduction. Friction stir welding is widely used due to certain advantages of this method. Factors that reduce the strength of joints made of high-strength aluminum alloys are considered. When welding flat sheets, an effective way to increase the strength of the weld is edge thickening. The paper proposes a method for such thickening. A device is developed, calculations and experiments are carried out. Materials and Methods. Laboratory equipment has been developed to provide simultaneous thickening of two edges to be welded. The main component of this equipment is a steel roller, which is rolled along the edges of two blanks and thickens them due to plastic deformation. The same setup can be used for the friction stir welding process. To calculate the geometry of the thickened edges and the parameters of the deforming roller depending on the value of the edge settlement, a mathematical model based on the contact problem for elastic (roller) and elastoplastic (blank) bodies with a bilinear hardening law has been developed. A three-dimensional simplified geometric model of the facility with account of its symmetry has been constructed. On the contact surfaces, special contact finite elements were selected and the finite element mesh was refined. The numerical implementation of the model was carried out in the ANSYS package. Results. The theoretical model provides assessing the stress-strain state of interacting elements. On the basis of the developed finite element model, the parameters of the thickened edges are calculated, and the geometry of the thickened edges is defined. Using the developed laboratory equipment, full-scale experiments on thickening the edges of the blanks were carried out. The experimental results confirm the adequacy of the developed theoretical model and calculations based on it. The possibility of adjusting the size of the thickened edges is shown.Discussion and Conclusion. A technology for obtaining thickened edges in places of welds is proposed. It will reduce the metal consumption of structures and ensure the bearing capacity of welded joints not lower than similar characteristics of the base metal. A theoretical model of the process is developed, and a numerical experiment providing the selection of the process parameters is carried out.
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Aranđelović, Mihajlo, Simon Sedmak, Radomir Jovičić, Srđa Perković, Zijah Burzić, Dorin Radu, and Zoran Radaković. "Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects." Materials 14, no. 17 (August 25, 2021): 4832. http://dx.doi.org/10.3390/ma14174832.
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Current standards related to welded joint defects (EN ISO 5817) only consider individual cases (i.e., single defect in a welded joint). The question remains about the behaviour of a welded joint in the simultaneous presence of several different types of defects, so-called multiple defects, which is the topic of this research. The main focus is on defects most commonly encountered in practice, such as linear misalignments, undercuts, incomplete root penetration, and excess weld metal. The welding procedure used in this case was metal active gas welding, a common technique when it comes to welding low-alloy low-carbon steels, including those used for pressure equipment. Different combinations of these defects were deliberately made in welded plates and tested in a standard way on a tensile machine, along with numerical simulations using the finite element method (FEM), based on real geometries. The goal was to predict the behaviour in terms of stress concentrations caused by geometry and affected by multiple defects and material heterogeneity. Numerical and experimental results were in good agreement, but only after some modifications of numerical models. The obtained stress values in the models ranged from noticeably lower than the yield stress of the used materials to slightly higher than it, suggesting that some defect combinations resulted in plastic strain, whereas other models remained in the elastic area. The stress–strain diagram obtained for the first group (misalignment, undercut, and excess root penetration) shows significantly less plasticity. Its yield stress is very close to its ultimate tensile strength, which in turn is noticeably lower compared with the other three groups. This suggests that welded joints with misalignment and incomplete root penetration are indeed the weakest of the four groups either due to the combination of the present defects or perhaps because of an additional unseen internal defect. From the other three diagrams, it can be concluded that the test specimens show very similar behaviour with nearly identical ultimate tensile strengths and considerable plasticity. The diagrams shows the most prominent yielding, with an easily distinguishable difference between the elastic and plastic regions. The diagrams are the most similar, having the same strain of around 9% and with a less obvious yield stress limit.
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Lacki, P., Z. Kucharczyk, R. E. Śliwa, and T. Gałaczyński. "Effect of Tool Shape on Temperature Field in Friction Stir Spot Welding." Archives of Metallurgy and Materials 58, no. 2 (June 1, 2013): 595–99. http://dx.doi.org/10.2478/amm-2013-0043.
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Friction stir welding (FSW) is one of the youngest methods of metal welding. Metals and its alloys are joined in a solid state at temperature lower than melting points of the joined materials. The method is constantly developed and friction stir spot welding (FSSW) is one of its varieties. In the friction stir spot welding process a specially designed tool is brought into rotation and plunged, straight down, in the joined materials. Heat is generated as a result of friction between the tool and materials, and plastic deformation of the joined materials. Softening (plastic zone) of the joined materials occurs. Simultaneously the materials are stirred. After removal of the tool, cooling down the stirred materials create a solid state joint. Numerical simulation of the process was carried out with the ADINA System based on the finite element method (FEM). The problem was considered as an axisymmetric one. A thermal and plastic material model was assumed for Al 6061-T6. Frictional heat was generated on the contact surfaces between the tool and the joined elements. The model of Coulomb friction, in which the friction coefficient depends on the temperature, was used. An influence of the tool geometry on heat generation in the welded materials was analysed. The calculations were carried out for different radiuses of the tool stem and for different angles of the abutment. Temperature distributions in the welded materials as a function of the process duration assuming a constant value of rotational tool speed and the speed of tool plunge were determined. Additionally, the effect of the stem radius and its height on the maximum temperature was analysed. The influence of tool geometry parameters on the temperature field and the temperature gradient in the welded materials was shown. It is important regarding the final result of FSSW.
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Ghoneam, S. M., A. A. Hamada, and M. I. El-Elamy. "Experimental and Analytical Investigations of the Dynamic Analysis of Adhesively Bonded Joints for Composite Structures." Solid State Phenomena 147-149 (January 2009): 663–75. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.663.
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Adhesively bonded joints are used extensively in various industries. Some imperfections like holes, thermal residual stresses occurring in the bolted, welded, riveted, and soldered joints don't take place in adhesively bonded joints. Hence, the main advantages of bonded joint are lightness, sealing, corrosion resistance, heat and sound isolation, damping, and quickly mounting facility which have been highly proved. This paper introduces an attempt to study the dynamic analysis of adhesively bonded joint for composite structures to investigate mainly the influences of lamina code number, bonded adhesive line configuration and boundary condition on the dynamic behavior of the test specimens containing composite assembly. The numerical based on the use of finite element model (FEM) modified by introducing unified mechanical properties are represented and applied to compute efficiently the Eigen-nature for composite bonded structures. The experimental tests are conducted to investigate such adhesive bonded joints using two different techniques. The first technique includes an ultrasonic technique in which the magnetostractive pulse echo delay-line for material characterization of composite material is used. The second technique is bassed on the use of the frequency response function method (FRF) applying the hammering method. The comparison between the numerical and experimental results proves that the suggested finite element models of the composite structural beams with bonded joints provide an efficient by accurate tool for the dynamic analysis of adhesive bonded joints. The damping capacity is inversely proportional to the stiffness of the bonded joint specimens. The type of the proportionality depends mainly on the bond line configuration type, lamina orientation, and boundary conditions. This in turn enables an accurate evaluation for selecting the proper characteristics of the specimens for controlling the present damping capacity and the proper resistance against deformation during the operating process. The present study provides an efficient non-destructive technique for the prediction of dynamic properties for an adhesive bonded joint for the studied composite structure systems. The coordination of the experimental and numerical techniques makes it possible to find an efficient tool for studying the dynamic performance of adhesively bonded joint for composite structures.
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Wernicke, R., and R. Pohl. "Underwater Wet Repair Welding and Strength Testing on Pipe-Patch Joints." Journal of Offshore Mechanics and Arctic Engineering 120, no. 4 (November 1, 1998): 237–42. http://dx.doi.org/10.1115/1.2829546.
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The underwater wet welding method for repairing of submerged structural members has been intensively developed during the last years. It is an economical and especially more time-independent procedure. The shortened repair duration is a major advantage in regions with rough sea climate as the North Sea area. During research projects the weldability and fatigue performance of pipe-patch connections have been tested. These joints are in use for repairing of collision indents. The shape of the actual used repair patch was optimized to the requirements of underwater wet welding at high tensile strength steels as BS4360 Gr 50D. Steel materials in this grade show problems in regard to high hydrogen susceptibility, and therefore cold cracking. The fatigue behavior of the patch-welded pipe structural member has been investigated. First test series were carried out using as-welded joints. In a second part of the project, post-weld-treated connections were tested. The weld seams on these joints were partially ground or hammer peened. The test results have been evaluated by means of the hot-spot concept and then faced with actual code requirements. Extensive strain gage measurements and finite-element calculations have been carried out to provide the stress state in the structural details.
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Meneghetti, Giovanni, and Carlo Guzzella. "The peak stress method to estimate the mode I notch stress intensity factor in welded joints using three-dimensional finite element models." Engineering Fracture Mechanics 115 (January 2014): 154–71. http://dx.doi.org/10.1016/j.engfracmech.2013.11.002.
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Kryshchuk, R. S. "INFLUENCE OF WINDING ENDS ON THE PARAMETERS OF PULSE INDUCTOR WITH U-SHAPED CORE." Tekhnichna Elektrodynamika 2020, no. 6 (October 21, 2020): 69–76. http://dx.doi.org/10.15407/techned2020.06.069.
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It is known from the scientific literature that magnetic pulse processing of electrically conductive non-magnetic sheet materials helps to reduce residual stresses, especially in welded joints. This is due to magnetoplastic and electroplastic effects. To create such effects in non-magnetic electrically conductive materials with welded joints, an inductor with pulsed magnetic field, U-shaped magnetic circuit and hollow conductor for possibility of active cooling of the winding is proposed. Such inductor allows inducing high-density pulsed currents in electrically conductive non-magnetic sheet materials with welded joints. It studies the parameters of the inductor - active resistance and inductance in the frequency-domain mode. The parameters calculated in two-dimensional and three-dimensional models are compared. The electromagnetic field is calculated using Maxwell equations and finite element method. Parameters of an ends of winding are determined by the difference in the parameters of the three-dimensional and two-dimensional models of the induction system. Resistance is calculated separately in the groove`s part of the winding, the outer part and on the frontal parts. The parameters of the induction system with a ferromagnetic core and non-magnetic thin-sheet alloy AMg6 are calculated for various values of complex amplitude of current in winding. Additionally, the parameters are calculated both without the magnetic core and without the non-magnetic metal. The quantitative comparison of the parameters of the three-dimensional model with the two-dimensional one is performed. The active resistance and inductance of end parts of the inductor are investigated by well-known analytical expressions from handbooks of electric machines. References 11, figures 3, tables 6.
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Zhao, Dawei, Yuanxun Wang, Peng Zhang, and Dongjie Liang. "Modeling and Experimental Research on Resistance Spot Welded Joints for Dual-Phase Steel." Materials 12, no. 7 (April 3, 2019): 1108. http://dx.doi.org/10.3390/ma12071108.
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Dual-phase steel has been employed in the automotive industry as it has the advantages of high strength, satisfying ductility, low yield ratio, and so on. A novel framework for the weld nugget size prediction and control using finite element modeling and experimental research was proposed in this paper. The two-dimensional axisymmetric numerical analysis model was established and the phase transition on thermal expansion coefficient was taken into account. The whole welding process was simulated and discussed using thermal elastic-plastic theory. To validate the predictive methods of developed weld nugget size and confirmation experiments were implemented with the same input parameters in the ranges of process parameters. The simulated weld nugget sizes were in good agreement with the experimental results except for extreme welding conditions. The microstructure of the welding zone was also investigated based on metallographic experiments and temperature field analysis. The welding parameters were adjusted using the model proposed in this paper so as to obtain the nugget size with pull out failure mode.
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My Nu, Ho Thi, Truyen The Le, Luu Phuong Minh, and Nguyen Huu Loc. "A Study on Rotary Friction Welding of Titanium Alloy (Ti6Al4V)." Advances in Materials Science and Engineering 2019 (March 10, 2019): 1–9. http://dx.doi.org/10.1155/2019/4728213.
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The selection of high-strength titanium alloys has an important role in increasing the performance of aerospace structures. Fabricated structures have a specific role in reducing the cost of these structures. However, conventional fusion welding of high-strength titanium alloys is generally conducive to poor mechanical properties. Friction welding is a potential method for intensifying the mechanical properties of suitable geometry components. In this paper, the rotary friction welding (RFW) method is used to study the feasibility of producing similar metal joints of high-strength titanium alloys. To predict the upset and temperature and identify the safe and suitable range of parameters, a thermomechanical model was developed. The upset predicted by the finite element simulations was compared with the upset obtained by the experimental results. The numerical results are consistent with the experimental results. Particularly, high upset rates due to generated power density and forging pressure overload that occurred during the welding process were investigated. The performances of the welded joints are evaluated by conducting microstructure studies and Vickers hardness at the joints. The titanium rotary friction welds achieve a higher tensile strength than the base material.
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Xue, He, Yuman Sun, Shun Zhang, Rehmat Bashir, Youjun Zhao, Hongliang Yang, Shuai Wang, and Yongjie Yang. "A Numerical Approach to Analyze Detail Mechanical Characteristic at the Crack Tip of SCC in Dissimilar Metal Welded Joints." Advances in Materials Science and Engineering 2021 (August 23, 2021): 1–12. http://dx.doi.org/10.1155/2021/8429051.
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The mechanical characteristic at the crack tip is one of the main factors affecting the stress corrosion cracking (SCC) in dissimilar metal welded joints (DMWJs). In this research, to evaluate the effect of heterogeneous material properties on the mechanical characteristic at the crack tip of DMWJs accurately, a heterogeneous material model of the SA508 Cl.3-Alloy 52M DMWJ was established based on USDFLD subroutine in ABAQUS. The comparison of the traditional “Sandwich” material model with the heterogeneous material properties, stress-strain conditions, and the plastic zone around the crack tip at the interference zone has been analyzed by the finite element method (FEM). The results indicated that the heterogeneous material model could characterize the mechanical properties of the SA508 Cl.3-Alloy 52M DMWJs accurately. In addition, the crack at the interface zone between materials will deflect along with the weld metal in two material models.
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Özdemir, Uğur, and Çınar Yeni. "Investigation of strength mis-match effect on elastic plastic fracture parameters in laser beam welded aluminium alloy joints using the finite element method." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 229, no. 3 (October 28, 2013): 218–25. http://dx.doi.org/10.1177/1464420713509084.
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Ait-Salem Duque, O., A. R. Senin, A. Stenti, M. De Munck, and F. Aparicio. "A methodology for the choice of the initial conditions in the model updating of welded joints using the fuzzy finite element method." Computers & Structures 85, no. 19-20 (October 2007): 1534–46. http://dx.doi.org/10.1016/j.compstruc.2007.01.016.
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Atanasovska, Ivana, Dejan Momčilović, and Ognjen Ristić. "The new tool insert design for prevention the rotation of horizontal wire during shear testing of welded fabric." Metallurgical and Materials Engineering 25, no. 2 (July 2, 2019): 163–70. http://dx.doi.org/10.30544/425.
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Many new requirements in the field of experimental mechanics, like testing of metallic materials, emphasize traceability and accuracy of test results as the end goal. These requirements have energy efficiency context too, due to the increase of mass productions of many finished and semi-finished products based on steel metallurgy. Combined, both of the above-noted perspectives impose the need for improvements of some of the existing test methods. This paper describes one such improvement, the developing of the new insert tool for testing of shear strength of the welded fabric, for civil engineering. The developed tool allows repeated testing of welded joints sampled from the welded fabric of different dimensions without tool changes and is generally related with the procedure for the determination of shear strength properties of different sizes of wires used for welded fabric. The construction of the tool insert allows aiming high operation safety and higher accuracy of results, which is described in detail. The paper also presents experimental results and the Finite Element Analysis performed in order to verify the impact of insert tool application on the testing results. The obtained results and conclusion about the possible contributions of the developed insert tool for extensively testing of welded fabric for civil engineering are discussed.
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Bashir, Rehmat, He Xue, Jianlong Zhang, Rui Guo, Nasir Hayat, Ganbo Li, and Yueqi Bi. "Effect of Material Macrostructural Parameters on Quantitative Stress Corrosion Cracking Plastic Zone Using Extended Finite Element Method in Welded Joints for Light Water Reactor Environment." Corrosion 76, no. 9 (June 9, 2020): 826–34. http://dx.doi.org/10.5006/3498.
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Alloy 600, a nickel-chromium alloy, has an outstanding corrosion resistance with excellent fabricability and is used in light water reactors at elevated temperatures. The alloy is also being considered for an advanced reactor concept because of its high allowable design strength at the elevated temperature. Alloy 600 is a power hardening material and basic plastic properties of the alloy are changed in the welded zone due to inhomogeneity in weld joints. The extended finite element method (XFEM) is used when the problem of variations invariably in the stress intensity factors (K) at a different instant rate exists. This paper focuses on the effect of variations in macrostructural properties of the alloy on stress corrosion cracking plastic zone ahead of the crack-tip using XFEM. To control the variations in the K, a new technique is also introduced in this research. The results show that the plastic zone is affected by K (increases with the increase of K), yield strength (plastic zone decreases with the increase in yield strength), and hardening exponent “n” (core region increases with the increase of exponent) of the materials. Simulations were performed and results are compared with experimental data.
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Nakacho, K., and Y. Ueda. "A Simple Estimating Method for Reduction of Welding Residual Stresses in Thick Welded Joint From Stress-Relief Annealing—Part I: Development of the Analytical Method for Relaxation Tests and Its Applicability." Journal of Pressure Vessel Technology 118, no. 3 (August 1, 1996): 343–50. http://dx.doi.org/10.1115/1.2842198.
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Stress-relief annealing (SR treatment) is often applied to relieve welding residual stresses in the fabrication process of pressure vessels, etc. This study aims at development of an efficient method as simple as hand calculation to estimate reduction of residual stresses of very thick welded joint by SR treatment. In this first report, an estimating method is developed for relaxation tests, in uniaxial stress state, at changing and constant temperatures because the stress relaxation phenomenon is very similar to that observed in the SR treatment of a joint. Using the various relations between stress and strains in the relaxation tests, estimating equations are formulated in order to simply calculate the change of the stress. The results obtained by applying the equations are compared with the highly accurate analytical result based on the finite element method. Both results show such a good coincidence that the appropriateness of the adopted method is confirmed. In the next report, this method is extended to SR treatment of a very thick welded joint, of which the stress state and boundary condition are very complex.
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Ivanchenko, Alexander B., I. P. Tochilin, and Aleksey V. Zhdanov. "Thermal State Simulation of Welded Steel Plates under Laser Welding Conditions." Solid State Phenomena 316 (April 2021): 396–401. http://dx.doi.org/10.4028/www.scientific.net/ssp.316.396.
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The article describes a method for determination of the welded parts temperature pattern under laser welding conditions. An algorithm is engineered to solve the non-stationary heat conduction problem by finite element method. The boundary conditions are determined by the molten pool parameters and depend on the welding regime characteristics. The dependencies for determining the molten pool geometric dimensions for laser welding conditions are proposed. Calculations of the temperature pattern change during the steel plates joint by laser welding are carried out. It is shown that the proposed model adequately describes the heat transfer process in the welding region.
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Zhang, Shun, He Xue, Shuai Wang, Yuman Sun, Fuqiang Yang, and Yubiao Zhang. "Effect of Mechanical Heterogeneity on Strain and Stress Fields at Crack Tips of SCC in Dissimilar Metal Welded Joints." Materials 14, no. 16 (August 9, 2021): 4450. http://dx.doi.org/10.3390/ma14164450.
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The crack tip strain and stress condition are one of the main factors affecting stress corrosion cracking (SCC) behaviors in the dissimilar metal welded joint of the primary circuit in the pressurized water reactor. The mechanical property mismatch of base metal and weld metal can significantly affect the stress and strain condition around the crack tip. To understand the effect of different weld metals on strain and stress fields at SCC crack tips, the effects of strength mismatch, work hardening mismatch, and their synergy on the strain and stress field of SCC in the bi-material interface, including plastic zone, stress state, and corresponding J-integral, are investigated in small-scale yielding using the finite element method. The results show a significant effect of the strength mismatch and work hardening mismatch on the plastic zone and stress state in the weld metal and a negligible effect in the base metal. J-integral decreases with the single increase in either strength mismatch or work hardening mismatch. Either the increase in strength mismatch or work hardening mismatch will inhibit the other’s effect on the J-integral, and a synthetic mismatch factor can express this synergistic effect.