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  • 1.
    Afshari, Davood
    et al.
    Univ Zanjan, Zanjan 4537138791, Iran..
    Mirzaahamdi, Soheil
    Univ Zanjan, Zanjan 4537138791, Iran..
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Residual Stresses in Resistance Spot Welded AZ61 Mg Alloy2019In: CMES - Computer Modeling in Engineering & Sciences, ISSN 1526-1492, E-ISSN 1526-1506, Vol. 118, no 2, p. 275-290Article in journal (Refereed)
    Abstract [en]

    The use of magnesium alloys has been rapidly increased due to their ability to maintain high strengths at light weights. However weldability of steels and aluminum alloys by using resistance spot weld (RSW) process is a major issue, because it cannot be directly utilized for magnesium alloys. In this study, a structural-thermal-electrical finite element (FE) model has been developed to predict the distribution of residual stresses in RSW AZ61 magnesium alloy. Thermophysical and thermomechanical properties of AZ61 magnesium alloy have been experimentally determined, and have been used in FE model to increase the accuracy of the model. X-ray diffraction (XRD) technique has been utilized to measure the residual stresses in welded samples, and its results have been used to validate the FE model. Comparison study shows that the results obtained by using FE model have a good agreement with the experimental XRD data. In specific, the results show that the maximum tensile residual stress occurs at the weld center while decreases towards the nugget edge. In addition, the effects of welding parameters such as electrical current, welding time, and electrode force have been investigated on the maximum tensile residual stress. The results show that the tensile residual stress in welded joints rises by increasing the electrical current; however, it declines by prolonging the welding time as well as increasing the electrode force.

  • 2.
    Afshari, Davood
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Iran University of Science and Technology, Iran.
    Sedighi, M.
    Karimi, M. R.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Prediction of residual stresses in resistance spot weld2016In: Aircraft Engineering and Aerospace Technology, ISSN 1748-8842, Vol. 88, no 4, p. 492-497Article in journal (Refereed)
    Abstract [en]

    Purpose - The purpose of this paper is to predict residual stresses in resistance spot weld of 2 mm thick aluminum 6061-T6 sheets. The joint use of finite element analysis and artificial neural networks can eliminate the high costs of residual stresses measuring tests and significantly shorten the time it takes to arrive at a solution. Design/methodology/approach - Finite element method and artificial neural network have been used to predict the residual stresses. Different spot welding parameters such as the welding current, the welding time and the electrode force have been used for the simulation purposes in a thermal-electrical-structural coupled finite element model. To validate the numerical results, a series of experiments have been performed, and residual stresses have been measured. The results obtained from the finite element analysis have been used to build up a back-propagation artificial neural network model for residual stresses prediction. Findings - The results revealed that the neural network model created in this study can accurately predict residual stresses produced in resistance spot weld. Using a combination of these two developed models, the residual stresses can be predicted in terms of spot weld parameters with high speed and accuracy. Practical implications - The paper includes implication for aircraft and automobile industries to predict residual stresses. Residual stresses can lower the strength and fatigue life of the spot-welded joints and determine the performance quality of the structure. Originality/value - This paper presents an approach to reduce the high costs and long times of residual stresses measuring tests.

  • 3.
    Afshari, Davood
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Sedighi, Mohammd
    Iran Univ Sci & Technol, Tehran, Iran.
    Barsoum, Zuhier
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Peng, Ru Lin
    Linkoping Tech Univ, Linkoping, Sweden .
    An approach in prediction of failure in resistance spot welded aluminum 6061-T6 under quasi-static tensile test2012In: Proceedings of the Institution of mechanical engineers. Part B, journal of engineering manufacture, ISSN 0954-4054, E-ISSN 2041-2975, Vol. 226, no B6, p. 1026-1032Article in journal (Refereed)
    Abstract [en]

    The aim of this article is to predict the failure load in resistance spot welded aluminum 6061-T6 sheets with 2mm thickness under quasi-static tensile test. Various welding parameters, e. g. welding current, welding time and electrode force are selected to produce welded joints with different quality. The results show that for all the samples in this study only interfacial failure mode was observed in tensile-shear test and no pull-out mode was observed. According to the failure mode, an empirical equation was used for the prediction of failure load based on nugget size and hardness of failure line. Microstructure study has been carried out to investigate microstructural changes in the welded joints. For determination of the minimum hardness, microhardness tests have been carried out to find hardness profiles. The minimum hardness value was observed for a thin layer around the nugget with large and coarse grains. The results show that by using the presented empirical equation, the failure can be predicted with a good agreement only by measuring nugget size.

  • 4.
    Afshari, Davood
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Sedighi, Mohammd
    Iran Univ Sci & Technol, Tehran, Iran.
    Karimi, M. R.
    Barsoum, Zuhier
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    On Residual Stresses in Resistance Spot-Welded Aluminum Alloy 6061-T6: Experimental and Numerical Analysis2013In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 22, no 12, p. 3612-3619Article in journal (Refereed)
    Abstract [en]

    In this study, an electro-thermal-structural-coupled finite element (FE) model and x-ray diffraction residual stress measurements have been utilized to analyze distribution of residual stresses in an aluminum alloy 6061-T6 resistance spot-welded joint with 2-mm-thickness sheet. Increasing the aluminum sheet thickness to more than 1 mm leads to creating difficulty in spot-welding process and increases the complexity of the FE model. The electrical and thermal contact conductances, as mandatory factors are applied in contact areas of electrode-workpiece and workpiece-workpiece to resolve the complexity of the FE model. The physical and mechanical properties of the material are defined as thermal dependent to improve the accuracy of the model. Furthermore, the electrodes are removed after the holding cycle using the birth-and-death elements method. The results have a good agreement with experimental data obtained from x-ray diffraction residual stress measurements. However, the highest internal tensile residual stress occurs in the center of the nugget zone and decreases toward nugget edge; surface residual stress increases toward the edge of the welding zone and afterward, the area decreases slightly.

  • 5.
    Afshari, Davood
    et al.
    School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran .
    Sedighi, Mohammd
    Iran Univ Sci & Technol, Tehran, Iran.
    Karimi, M. R.
    Barsoum, Zuhier
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Prediction of the nugget size in resistance spot welding with a combination of a finite-element analysis and an artificial neural network2014In: Materiali in tehnologije, ISSN 1580-2949, E-ISSN 1580-3414, Vol. 48, no 1, p. 33-38Article in journal (Refereed)
    Abstract [en]

    The goal of this investigation is to predict the nugget size for a resistance spot weld of thick aluminum 6061-T6 sheets 2 mm. The quality and strength of spot welds determine the integrity of the structure, which depends thoroughly on the nugget size. In this study, the finite-element method and artificial neural network were used to predict the nugget size. Different spot welding parameters such as the welding current and the welding time were selected to be used for a coupled, thermal-electrical-structural finite-element model. In order to validate the numerical results a series of experiments were carried out and the nugget sizes were measured. The results obtained with the finite-element analysis were used to build up a back-propagation, artificial-neural-network model for the nugget-size prediction. The results revealed that a combination of these two developed models can accurately and rapidly predict the nugget size for a resistance spot weld.

  • 6.
    Ahola, A.
    et al.
    Lappeenranta Lahti Univ Technol LUT, Sch Energy Syst, POB 20, FI-53851 Lappeenranta, Finland..
    Bjork, T.
    Lappeenranta Lahti Univ Technol LUT, Sch Energy Syst, POB 20, FI-53851 Lappeenranta, Finland..
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Fatigue strength capacity of load-carrying fillet welds on ultra-high-strength steel plates subjected to out-of-plane bending2019In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 196, article id UNSP 109282Article in journal (Refereed)
    Abstract [en]

    Weld root fatigue strength capacity is an important design criterion in load-carrying (LC) fillet welded joints subjected to cyclic loads. This paper elaborates on the weld root fatigue strength capacity of fillet welded LC joints made of ultra-high-strength steel (UHSS) and subjected to out-of-plane bending. Experimental fatigue tests are carried out using constant amplitude loading with an applied stress ratio of R = 0.1 with both pure axial, i.e. DOB = 0 (degree of bending, bending stress divided by total stress) and bending, i.e. DOB = 1.0, load conditions. The applicability of different approaches - nominal weld stress, effective notch stress concepts, and 2D linear elastic fracture mechanics (LEFM) - for the fatigue strength assessment of weld root capacity is evaluated. Furthermore, a parametric LEFM analysis is used to evaluate the effect of weld penetration on the root fatigue strength capacity in axial and bending loading. The results indicate that in the case of bending, nominal weld stress can be calculated using the linear stress distribution over the joint section and FAT36 as a reference curve. In the bending loading, for the joints failing from the weld toe, a mean fatigue strength of up to 185 MPa in the nominal stress system was achieved, indicating that the reference curve FAT63 is overly conservative. The ENS concept with FAT225 seemed to be slightly unconservative for assessing the root fatigue strength capacity. LEFM analyses revealed that in the case of increasing weld penetration and bending loading, weld root fatigue strength capacity seemed to correlate with the nominal weld stress calculated using effective weld throat thickness, while in axial loading, weld stress should be calculated using external throat thickness summed with penetration length.

  • 7. Alam, M M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsen, P
    Kaplan, A F H
    Haggblad, H A
    Influence of defects on fatigue crack propagation in laser hybrid welded eccentric fillet joint2011In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 78, no 10, p. 2246-2258Article in journal (Refereed)
    Abstract [en]

    Fatigue cracking of laser hybrid welded eccentric fillet joints has been studied for stainless steel. Two-dimensional linear elastic fracture mechanics analysis was carried out for this joint geometry for four point bending load. The numerical simulations explain for the experimental observations why the crack propagates from the lower weld toe and why the crack gradually bends towards the root. Lack of fusion turned out to be uncritical for the initiation of cracks due to its compressive stress conditions. The linear elastic fracture mechanics analysis has demonstrated in good qualitative agreement with fatigue test results that lack of fusion slightly (<10%) reduces the fatigue life by accelerating the crack propagation. For the geometrical conditions studied here improved understanding of the crack propagation was obtained and in turn illustrated. The elaborated design curves turned out to be above the standard recommendations.

  • 8. Alam, M. M.
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsén, P.
    Kaplan, A. F. H.
    Häggblad, H. A.
    The influence of surface geometry and topography on the fatigue cracking behaviour of laser hybrid welded eccentric fillet joints2010In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 256, no 6, p. 1936-1945Article in journal (Refereed)
    Abstract [en]

    Laser hybrid welding of an eccentric fillet joint causes a complex geometry for fatigue load by 4-point bending. The weld surface geometry and topography were measured and studied in order to understand the crack initiation mechanisms. The crack initiation location and the crack propagation path were studied and compared to Finite Element stress analysis, taking into account the surface macro-and micro-geometry. It can be explained why the root and the upper weld toe are uncritical for cracking. The cracks that initiate from the weld bead show higher fatigue strength than the samples failing at the lower weld toe, as can be explained by a critical radius for the toe below which surface ripples instead determine the main stress raiser location for cracking. The location of maximum surface stress is related to a combination of throat depth, toe radius and sharp surface ripples along which the cracks preferably propagate.

  • 9. Alam, M. M.
    et al.
    Kaplan, A. F. H.
    Tuominen, J.
    Vuoristo, P.
    Miettinen, J.
    Poutala, J.
    Näkki, J.
    Junkala, J.
    Peltola, T.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Analysis of the stress raising action of flaws in laser clad deposits2013In: Materials and Design, ISSN 0261-3069, Vol. 46, p. 328-337Article in journal (Refereed)
    Abstract [en]

    Fatigue cracking of laser clad cylindrical and square section bars depends upon a variety of factors. This paper presents Finite Element Analysis (FEA) of the different macro stress fields generated as well as stress raisers created by laser cladding defects for four different fatigue load conditions. As important as the defect types are their locations and orientations, categorized into zero-, one- and two-dimensional defects. Pores and inclusions become critical close to surfaces. The performance of as-clad surfaces can be governed by the sharpness of surface notches and planar defects like hot cracks or lack-of-fusion (LOF) are most critical if oriented vertically, transverse to the bar axis. The combination of the macro stress field with the defect type and its position and orientation determines whether it is the most critical stress raiser. Based on calculated cases, quantitative and qualitative charts were developed as guidelines to visualize the trends of different combinations.

  • 10. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Häggblad, Hans Åke
    Jonsén, Pär
    Kaplan, Alexander
    The Effects of Surface Topography and Lack of Fusion on The Fatigue Strength of Laser Hybrid Welds2009In: Congress proceedings: ICALEO, 28th International Congress on Applications of Lasers & Electro-Optics, 2009, p. 38-46Conference paper (Refereed)
    Abstract [en]

    The geometrical aspects of laser hybrid welds (before, during and after the process) differ from autonomous laser welding and from arc welding. When studying the fatigue behaviour of laser hybrid welded fillet joints we identified that the micro-topography (i.e. the surface ripples) can be more important than the macrogeometry of the weld surface or lack of fusion (LOF), which frequently was detected. The plastic replica method was applied to measure the toe radii at the weld edges while the micro-topography was identified by interferometric profilometry. From metallurgical analysis of the joint interface, the tendency to LOF can be explained. Stress analysis was carried out by Finite element analysis (FEA) for the complex joint geometry and a bending load situation, showing maximum stress on the weld toes, even when including LOF. It was shown that the position and value of the maximum stress depends on a non-trivial combination of the weld geometry, including possible LOF, and the surface micro-topography. Thus it can be explained that at compressive stress conditions LOF does not contribute significantly to the fatigue strength of laser hybrid welds while the surface topography does. Recommendations for defining and in turn avoiding critical geometrical aspects during the welding process are discussed.

  • 11. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsén, Pär
    Häggblad, Hans Åke
    Kaplan, Alexander
    Fatigue behaviour study of laser hybrid welded eccentric fillet joints – Part II: State-of-the-art of fracture mechanics and fatigue analysis of welded joints2009In: 12th NOLAMP proceeding 2009: Nordic Laser Materials Processing Conference / [ed] Erling Dam Mortensen, 2009Conference paper (Other academic)
    Abstract [en]

    Simplified fatigue and fracture mechanics based assessment methods are widely used by the industry to determine the structural integrity significance of postulated cracks, manufacturing flaws, service-induced cracking or suspected degradation of engineering components under normal and abnormal service loads. In many cases, welded joints are the regions most likely to contain original fabrication defects or cracks initiating and growing during service operation. The welded joints are a major component that is often blamed for causing a structure failure or for being the point at which fatigue or fracture problems initiate and propagate. Various mathematical models/techniques for various classes of welded joints are developed by analytically or by simulation software's that can be used in fatigue and fracture assessments. This literature survey compiled useful information on fracture and fatigue analysis of various welded joints. The present review is divided into two major sections- fracture mechanics and fatigue analysis with widely used models. A survey table is also introduced to get the outlook of research trend on fatigue and fracture over last 3 decades. Although tremendous research effort has been implemented on fatigue and fracture analysis of conventional welding, research on relatively new welding technology (laser welding, hybrid laser welding) is still limited and unsatisfactory. In order to give guarantee or make welding standard for new welding technology, further research is required in the field of fatigue and fracture mechanics including FEM and multi-scale modeling.

  • 12. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsén, Pär
    Häggblad, Hans Åke
    Kaplan, Alexander
    Geometrical Aspects of The Fatigue Behaviour of Laser Hybrid Fillet Welds2009In: Proceedings of the Fatigue Design Conference, 2009Conference paper (Refereed)
  • 13. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Josén, Per
    Häggblad, Hans Åke
    kaplan, Alexander
    Fatigue Behaviour Study of Laser Hybrid Welded Eccentric Fillet Joints - Part I2009In: 12th NOLAMP proceeding 2009: Nordic Laser Materials Processing Conference / [ed] Erling Dam Mortensen, 2009Conference paper (Other academic)
    Abstract [en]

    Welded joints are a major component that is often responsible for causing a structure failure or for being the point at which fatigue cracking initiates and propagates. Despite tremendous research efforts, the understanding of fatigue behaviour is still limited, particularly for new techniques like laser hybrid welding. Beside a comprehensive state-of-the-art study, the paper presents a fatigue study of laser hybrid welded eccentric fillet joint of stainless steel of 10 mm thickness, with 5 mm displacement. Motivation is to study the influence of the surface geometry shape on fatigue performance under a four point bending test. 13 samples were produced, measuring the toe radii and testing under constant amplitude loading with stress ratio R=0. Different techniques have been used to measure local weld geometry, like plastic replica, a 3D optical profiler and a 3D-digitizer. The influence of the local weld geometry, like the toe radii, on the stress concentration was studied by FE-analysis. Occasionally lack of fusion was observed, which was taken into account in the FE-analysis. Based on the nominal stress approach, SN-curves were designed for laser hybrid welded eccentric fillet joints. Macro hardness tests were carried out and the crack surfaces were observed in order to detect crack initiation and propagation. Correlations between the toe radii, the corresponding stress maxima and crack initiation locations were studied between the different samples and even along the welds.

  • 14. Aygul, Mustafa
    et al.
    Al-Emrani, Mohammad
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Khalifa University of Science Research and Technology, United Arab Emirates.
    Leander, John
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    An investigation of distortion-induced fatigue cracking under variable amplitude loading using 3D crack propagation analysis2014In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 45, p. 151-163Article in journal (Refereed)
    Abstract [en]

    The distortion-induced fatigue cracks in the welded details of the Soderstrom Bridge are analytically and numerically investigated by performing 3D crack propagation analyses with variable amplitude fatigue loading. In the crack propagation analyses, the effects of bridge loading are defined on the basis of the field measurements in order to simulate crack growth and predict the residual fatigue life of the studied detail as accurately as possible. The effect of crack closure and crack direction while considering the most common criteria is also studied. The results are compared with those obtained from the crack propagation analyses with constant amplitude fatigue loading presented in Ayg l et al. [1]. The results of the crack growth simulations with variable amplitude fatigue loading have generally shown good agreement with the real crack formation and reveal that the crack growth rates are different in different directions. The crack behaviour in the damaged detail is mainly controlled by the loading and geometrical arrangement of the detail components. There is generally a significant difference between constant and variable amplitude fatigue crack growth analyses and the variable amplitude fatigue crack growth analyses yield more conservative results. The main reason for this difference is the bridge loading and the number of stress cycles defined in the analyses. The crack direction criteria studied in this investigation showed basically the same crack formation and crack growth rate.

  • 15. Aygül, M.
    et al.
    Al-Emrani, M.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Leander, John
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Investigation of distortion-induced fatigue cracked welded details using 3D crack propagation analysis2014In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 64, p. 54-66Article in journal (Refereed)
    Abstract [en]

    The behaviour of distortion-induced fatigue cracks in welded details in an existing bridge was studied analytically by performing crack propagation analysis based on linear elastic fracture mechanics. The real load history of the bridge was obtained from strain measurements. These loads were utilised to examine the crack growth rate and the residual service life of the cracked detail. Moreover, the effectiveness, accuracy and applicability of the crack propagation analysis on bridge structures were investigated by simulating a complex case of fatigue cracking using several crack propagation analyses. The results of the analyses revealed that the fatigue crack in the studied details had significantly different crack growth characteristics in different directions. In the thickness direction, for instance, the crack was seen to propagate at a certain rate, which increased with the propagated crack from the beginning and, as expected, the crack propagation rate decreased when the crack grew longer. The crack was subsequently arrested half way through the thickness of the plate. In the longitudinal direction, the crack was not, however, arrested in the same way as in the thickness direction and it continued to propagate at a reduced yet constant crack growth rate. The results also revealed that, even though distortion-induced fatigue cracking was usually caused by a mixed-mode condition (i.e. a combination of modes I, II and III), the governing propagation mode is still mode I. Furthermore, it was also observed that the contribution of modes II and III to crack propagation was very little and dependent on the location of the propagated crack front, as well as the geometrical configuration of the cross-beam.

  • 16.
    Barsoum, I.
    et al.
    Khalifa Univ Sci & Technol, Dept Mech Engn, Petr Inst, POB 2533, Abu Dhabi, U Arab Emirates..
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Islam, M. D.
    Khalifa Univ Sci & Technol, Dept Mech Engn, Petr Inst, POB 2533, Abu Dhabi, U Arab Emirates..
    Thermomechanical Evaluation of the Performance and Integrity of a HDPE Stub-End Bolted Flange Connection2019In: Journal of Pressure Vessel Technology-Transactions of the ASME, ISSN 0094-9930, E-ISSN 1528-8978, Vol. 141, no 5, article id 051206Article in journal (Refereed)
    Abstract [en]

    In this study, the integrity of a manhole structure made of a 78 in. high density polyethylene (HDPE) stub-end, steel ring, and blind flange, sealed with a compressed nonasbestos fiber (CNAF) gasket is investigated by means of a parametric finite element analysis (FEA). A coupled thermomechanical nonlinear FEA model is built, comprising of a heat transfer and a structural model, which allows modeling the complex thermal and mechanical loads and their interactions present during the operation of the manhole. The temperature-dependent elastic-plastic HDPE material constitutive behavior and the temperature-dependent nonlinear response of the CNAF gasket are accounted for in the model. Factors influencing the performance and integrity of the manhole such as stud-bolt pretorque level (T-b), internal pressure (P-i), and outer temperature (T-o) are considered. Based on the results, the integrity and performance of the structure are assessed in view of a leakage through the gasket criterion and a yielding of the HDPE stub-end criterion. The FEA results reveal that both T-b, P-i, and T-o significantly influence the performance (i.e., leakage) of the gasket and the integrity (i.e., yielding) of the HDPE stubend. At 40 degrees C, it is possible to find a safe operational window for a range of T-b and P-i values, where no leakage through the gasket or yielding of the stub-end occurs. However, as the temperature is increased this safe operational window decreases considerably, and at 80 degrees C safe operation cannot be guaranteed where leakage, yielding, or both simultaneously, will lead to loss in performance and integrity of the manhole structure.

  • 17. Barsoum, I.
    et al.
    Khan, F.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Analysis of the torsional strength of hardened splined shafts2014In: Materials and Design, ISSN 0261-3069, Vol. 54, p. 130-136Article in journal (Refereed)
    Abstract [en]

    The current study presents a finite element modeling framework to determine the torsion strength of hardened splined shafts by taking into account the detailed geometry of the involute spline and the material gradation due to the hardness profile. The aim is to select a spline geometry and hardness depth that optimizes the static torsion strength. Six different spline geometries and seven different hardness profiles including non-hardened and through-hardened shafts have been considered. The results reveal that the torque causing yielding of induction hardened splined shafts is strongly dependent on the hardness depth and the geometry of the spline teeth. The results from the model agree well with experimental results found in the literature and reveal that an optimum hardness depth maximizing the torsional strength can be achieved if shafts are hardened to half their radius.

  • 18.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Avancerade metoder för noggrannare dimensionering av svetsade konstruktioner2009In: Svetsen, ISSN 0039-7091, Vol. 68, no 3Article in journal (Other (popular science, discussion, etc.))
  • 19.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Fatigue Assessment of Cruciform Joints Welded with Different Methods2005In: IIW Doc. No. XIII-2074-05, 2005Conference paper (Other academic)
  • 20.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Fatigue design of welded structures: effect of weld quality and residual stresses, XIII-2312-102010Conference paper (Other academic)
  • 21.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Fatigue Strength of cruciform joints fabricated with different welding processes2007In: International Symposium on Integrated Design and Manufacturing of Welded Structures, Eskilstuna, 2007Conference paper (Other academic)
  • 22.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    HENRY GRANJON PRIZE COMPETITION 2010 Winner Category C: "Design and Structural Integrity" FATIGUE DESIGN OF WELDED STRUCTURES - SOME ASPECTS OF WELD QUALITY AND RESIDUAL STRESSES2011In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 55, no 11-12, p. 2-11Article in journal (Refereed)
    Abstract [en]

    The research work reported in this paper aims to increase the accuracy of fatigue life prediction of welded steel structures using local analysis methods by i) establishing a link between weld quality and fatigue life ii) developing simplified engineering methods using finite element routines for prediction of welding residual stresses iii) incorporating the residual stresses into the fatigue life predictions. Acceptance criteria were developed for the weld quality by comprehensive FE-and fracture mechanical analysis and fatigue testing. The results are the foundation for the new weld class system within the Volvo group company. Simplified FE welding simulation routines and procedures for incorporating the predicted residual stresses into crack growth analysis were developed showing good agreement with residual stress measurements and fatigue testing.

  • 23.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Local weld geometry and the influence on fatigue strength2010In: Proceedings of the Swedish Conference on Lightweight Optimised Welded Structures: Borlänge, March 24-25, 2009 / [ed] Zubeir Barsoum, Jack Samuelsson, Borlänge, 2010, p. 26-38Conference paper (Other academic)
  • 24.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Numerical Analysis and Measurement of Residual Stresses in Multi Pass Welding - Influence on Fatigue Root Crack Propagation2006In: TRENDS IN WELDING RESEARCH, PROCEEDINGS / [ed] David SA; DebRoy T; Lippold JC; Smartt HB; Vitek JM, MATERIALS PARK: ASM INTERNATIONAL , 2006, p. 589-594Conference paper (Refereed)
    Abstract [en]

    The purpose of this study is to investigate the residual stresses near the weld root and the weld toe for multi-pass welded tube-to-plates, and the influence of residual stresses on multiaxial fatigue of tubular joints. Two different tubular joint configurations were studied; a three-pass single-U weld groove for maximum weld penetration and a two-pass fillet (no groove) welded tube-to-plates for minimum weld penetration. An axi-symmetric finite element model was developed to calculate the temperature distribution, HAZ, penetration depth and the residual stress distribution for the sequentially coupled thermo-mechanical analysis. The calculated geometry and the temperature distribution of the fusion zone showed good agreement with the micro samples of the welds. The calculated residual stresses was compared with experimental results and showed qualitatively good agreement. The "design root crack" is under compressive stresses in both configuration, -230 MPa for the single-U weld groove and -120 MPa for the fillet weld, respectively. Also the weld toe, transition between weld and tube, is under compressive stresses. Multi-axial fatigue tests were performed in order to study weld root crack propagation. The tube structures were loaded with a static internal pressure in order to separate the design root crack and initiate the crack growth. The fatigue tests show that, depending on the size of the static imposed internal pressure, different crack paths are received.

  • 25.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Ny doktorsavhandling: Restspännings- och utmattningsanalyser av svetsade stålkonstruktioner2008In: Svetsen, ISSN 0039-7091, Vol. 67, no 3Article in journal (Other (popular science, discussion, etc.))
  • 26.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Prediction of Welding Residual Stresses2007In: International Symposium on Integrated Design and Manufacturing of Welded Structures, Eskilstuna, 2007Conference paper (Other academic)
  • 27.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Prediction of welding residual stresses by simplified approaches2010In: Proceedings of the Swedish Conference onLightweight Optimised Welded Structures: Borlänge, March 24-25, 2009 / [ed] Zubeir Barsoum, Jack Samuelsson, Stockholm: KTH Royal Institute of Technology, 2010, p. 39-50Conference paper (Other academic)
  • 28.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Residual Stress Analysis and Fatigue Assessment of Welded Steel Structures2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This doctoral thesis is concerned with fatigue life of welded structures. Several topics related to fatigue of welded structures are treated such as; weld defects and their influence on fatigue performance of welded structures, fatigue life prediction using LEFM (Linear Elastic Fracture Mechanics), fatigue testing, welding simulation, residual stress prediction and measurement and their influence on fatigue life.

    The work that is reported in this doctoral thesis is part results of the Nordic R&D project QFAB (Quality and Cost of Fabricated Advanced Welded Structures) and the Swedish R&D project LOST (Light Optimized Welded Structures). One of the main objectives is to compare different welding processes for the fatigue performance, weld quality and gain understanding of the weld defects, their appearance in different welding processes and their effect on fatigue life. Another main objective is to study welding residual stresses and their effect on fatigue. The design rules are in some cases conservative and especially on the weld root sides the knowledge about the residual stress field may improve the life prediction. The aim is to develop simplified procedures for analysis of residual stresses, their relaxation and influence on fatigue life.

    Fatigue testing of Hybrid Nd: YAG laser/MAG and MAG welded (tandem arc solid wire, flux cored wire, tandem flux cored wire) non-load carrying cruciform joints was carried out. Four batches were produced, tested and the results were compared. The local weld geometry of the cruciform welded joints was measured and analyzed. Residual stress measurement was carried out close to the toe region using X-ray diffraction. Weld defects, in most cases cold laps, in the cracked specimens were measured.

    Further fatigue testing, weld defect assessment and residual stress and local weld geometry measurements were carried out on joints welded with flux cored and metal cored arc wires. Two-and three dimensional LEFM crack growth analysis were carried out in order to predict the influence of weld defects, local weld geometry and residual stresses.

    Residual stresses in multi-pass welded tube-to-plates were studied for two different tubular joint configurations; a three-pass single-U weld groove for maximum weld penetration and a two-pass fillet (no groove) welded tube-to-plates for minimum weld penetration. Torsion fatigue tests were performed in order to study crack propagation from the weld root. Mode III propagation from the lower and upper weld toe on the same tubular joints was also studied. Some tubes were stress relieved (PWHT) and some were fatigue tested with internal static pressure.

    A three dimensional finite element welding simulation of the multi-pass welded tubular joint was carried out. The calculated temperatures in the transient thermal analysis were compared with measured temperatures. The FE predicted residual stresses in the as-welded conditions were verified with hole drilling strain gage measurements. The residual stresses were used as internal stresses in the finite element model for the torsion fatigue simulation in order to study the cycle by cycle relaxation of the residual stresses in constant amplitude torsion loading.

    A two dimensional finite element welding simulation procedure was developed in order to predict welding residual stress. The predicted residual stresses were used together with a developed 2D LEFM subroutine to predict the fatigue life, crack path and the effect of residual stresses on weld root defects. The developed simulation subroutines were validated with results found in the literature.

    Residual stresses measurement, two-and three dimensional welding simulations were carried out in fillet welded joints in order to study the three dimensional effects of the welding process, boundary conditions and modelling technique on the formation of residual stresses.

  • 29.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Residual Stress Analysis and Fatigue of Multi-pass Welded Tubular Structures2008In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 15, no 7, p. 863-874Article in journal (Refereed)
    Abstract [en]

    The purpose of this study is to investigate the residual stresses near the weld root and the weld toe for multi-pass welded tube-to-plates. Two different tubular joint configurations were studied; a three-pass single-U weld groove for maximum weld penetration and a two-pass fillet (no groove) welded tube-to-plates for minimum weld penetration. A 2D axi-symmetric finite element model was developed to calculate the temperature distribution, HAZ, penetration depth and the residual stress distribution for the sequentially coupled thermo-mechanical analysis. The calculated residual stresses was compared with experimental results and showed qualitatively good agreement. Torsion fatigue tests were performed in order to study crack propagation from the weld root, lower and upper weld toe in mode III. Some of the tube structures were loaded with a static internal pressure in order to separate the root crack and initiate the crack growth in mode III. Another batch was PWHT and fatigue tested, in order to study the influence of residual stresses.

  • 30.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Residual Stress Analysis and Fatigue of Welded Structures2006Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This licentiate thesis is generally concerned with the fatigue of welded structures. Several topics related to fatigue of welded structures are treated such as; weld defects and their influence on fatigue performance of welded structures, fatigue life prediction using LEFM (Linear Elastic Fracture Mechanics), fatigue testing, welding simulation, residual stress prediction and measurement and their influence on fatigue. The work that is reported in this thesis is a part result of a Nordic research project QFAB (Quality and Cost of Fabricated Advanced Welded Structures). One of the main objectives is to compare different welding processes in fatigue performance, weld quality and gain understanding of the weld defects, their appearance in different welding processes and their influence on fatigue life. Another main objective is to study welding residual stresses and their effect on fatigue. The design rules are in some cases conservative and especially on root sides the knowledge about the residual stress field may improve the life prediction. The aim is to develop simplified procedures for analysis of residual stresses, their relaxation and influence on fatigue life. In one study fatigue testing of Hybrid Nd: YAG laser/MAG and MAG welded (tandem arc solid wire, flux cored wire, tandem flux cored wire) non-load carrying cruciform joints was carried out. Four batches were produced, tested and the results were compared. The local weld geometry of the cruciform welded joints was measured and analyzed. Residual stress measurement was carried out close to the toe region using X-ray diffraction. Weld defects, in most cases cold laps, in the cracked specimens was measured. Residual stresses in multi-pass welded tube-to-plates were studied for two different tubular joint configurations; a three-pass single-U weld groove for maximum weld penetration and a two-pass fillet (no groove) welded tube-to-plates for minimum weld penetration. Torsion fatigue tests were performed in order to study crack propagation from the weld root. Mode III propagation from the lower and upper weld toe on the same tubular joints was also studied. Some tubes were stress relieved (PWHT) and some were fatigue tested with internal static pressure. A three dimensional finite element welding simulation of the 3 pass welded tubular joint was carried out. The calculated temperatures in the transient thermal analysis were compared with measured temperatures. The FE predicted residual stresses in the as-welded conditions were verified with hole drilling strain gage measurements. The residual stresses were used as internal stresses in the finite element model for the torsion fatigue simulation in order to study the cycle by cycle relaxation of the residual stresses in constant amplitude torsion loading.

  • 31.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Residual stress predictin and relaxation in welded tubular joints under constant cyclic loading2006In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 524-525, p. 323-330Article in journal (Refereed)
    Abstract [en]

    In this paper three-dimensional welding simulations were carried out in FE software ANSYS in order to predict transient temperatures and the residual stresses in a three pass welded tubular joints. The thermal analysis and the moving heat source were verified with temperature measurements and the computed residual stresses were verified with hole drilling measurements. Then residual stress relaxation analyses were carried out on the tubular structure, with similar load cases as in earlier fatigue testing on the same tubular joint structures.

  • 32.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Residual Stress Prediction and Relaxation in Welded Tubular Joint2007In: Welding in the World, ISSN 0043-2288, Vol. 51, no 1/2, p. 23-30Article in journal (Refereed)
    Abstract [en]

    In this paper a three-dimensional welding simulation was carried out in the FE software ANSYS in order to predicttransient temperatures and the residual stresses in a three-pass welded tubular joint structure. The thermal analysisand the moving heat source were verified with temperature measurements, and the computed residual stresseswere verified with hole drilling measurements. The calculated and measured temperatures were in good agreement,and the computed residual stresses were in qualitatively good agreement with the experimental results. Residual stressrelaxation analyses were carried out with similar load as in earlier fatigue testing on the same tubular joint structure.The FE residual stress relaxation analysis showed a small amount of relaxation early in the fatigue life.

  • 33.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Residual stress prediction and relaxation in welded tubular joints under constant cyclic loading2006In: Residual Stresses VII / [ed] Reimers, W; Quander, S, 2006, Vol. 524-525, p. 323-328Conference paper (Refereed)
    Abstract [en]

    In this paper three-dimensional welding simulations were carried out in FE software ANSYS in order to predict transient temperatures and the residual stresses in a three pass welded tubular joints. The thermal analysis and the moving heat source were verified with temperature measurements and the computed residual stresses were verified with hole drilling measurements. Then residual stress relaxation analyses were carried out on the tubular structure, with similar load cases as in earlier fatigue testing on the same tubular joint structures.

  • 34.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Barsoum, Imad
    Residual stress effects on fatigue life of welded structures using LEFM2008Conference paper (Refereed)
  • 35.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Barsoum, Imad
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Residual stress effects on fatigue life of welded structures using LEFM2009In: IIW International Institute of Welding: 62nd AnnualAssembly, 2009Conference paper (Other academic)
  • 36.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Barsoum, Imad
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Residual stress effects on fatigue life of welded structures using LEFM2009In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 16, no 1, p. 449-467Article in journal (Refereed)
    Abstract [en]

    In this paper a welding simulation procedure is developed using the FE software ANSYS in order to predict residual stresses. The procedure was verified with temperature and residual stress measurements found in the literature on multi-pass butt welded plates and T-fillet welds. The predictions show qualitative good agreement with experiments. The welding simulation procedure was then employed on a welded ship engine frame box at MAN B&W. A subroutine for LEFM analysis was developed in 2D in order to predict the crack path of propagating fatigue cracks. The objective was to investigate fatigue test results from special designed test bars from the frame box where all test failed from the non-penetrated weld root. A subroutine was developed in order to incorporate the predicted residual stresses and their relaxation during crack propagation by isoparametric stress mapping between meshes without and with cracks, respectively. The LEFM fatigue life predictions shows good agreement with the fatigue test result when the residual stresses are taken into account in the crack growth analysis.

  • 37.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Khalifa University.
    Bhatti, Ayjwat
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Balawi, S.
    Computational Weld Mechanics - Towards a Simplified and Cost Effective Approach for Large Welded Structures2015In: Procedia Engineering, 2015, p. 62-69Conference paper (Refereed)
    Abstract [en]

    The current paper presents the development of a finite element analysis framework for computational weld mechanics, in order to carry out cost-effective predictions of welding induced residual stresses with good accuracy. Different approaches for describing the welding heat sources were investigated. The paper also investigates the influence of thermo-mechanical material properties of frequently used steel grades (S355-S960) on welding residual stresses and angular distortion. The predicted residual stresses were validated experimentally on several different small scale specimens with X-ray diffraction techniques. Finally, the developed simulation framework is demonstrated on complex welded structures in a construction equipment vehicle.

  • 38.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Khalifa University.
    Ghanadi, M.
    Balawi, S.
    Managing Welding Induced Distortion - Comparison of Different Computational Approaches2015In: Procedia Engineering, Elsevier, 2015, p. 70-77Conference paper (Refereed)
    Abstract [en]

    This study aims to assess and compare three different approaches of inherent strain method for prediction of welding induced distortion; inherent strain, inherent deformation and shrinkage force approaches. The FEA was performed on T-fillet welded structures. The results are compared with elastic-plastic FEA and experiments and shows a qualitative good agreement. It is found that the inherent strain and inherent deformation approaches are suitable to predict transverse shrinkage and transverse bending whereas to predict the longitudinal shrinkage and longitudinal bending the shrinkage force approach is more suitable.

  • 39.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Gustafson, Mats
    Spectrum fatigue of high strength steel joints welded with low temperature transformation consumables2007In: 2nd International Conference on Fatigue Design, 2007Conference paper (Refereed)
    Abstract [en]

    In the present paper constant (CA) and variable amplitude (VA) fatigue testing have been carried out on out-ofplane gusset fillet welded high strength steel joints. The joints were welded with conventional weld fillermaterial and martensitic low transformation temperature weld filler, LTT, in order to study the influence of theresidual stress on the fatigue strength. Residual stress measurements were carried out close to the weld toe usingX-ray diffraction technique in order to study the relaxation due to VA fatigue. The residual stress showeddifferent level of relaxation depending on the VA spectrum loading used. The LTT joints shows ~40% increasein mean fatigue strength compared to the conventional joints in CA. The LTT joints shows ~12% increase inmean fatigue strength compared to the conventional joints. The LTT joints shows 33% increase in mean fatiguestrength in CA compared to VA testing. However, the improvement of the fatigue strength is less significant invariable amplitude testing mainly due to the relaxation of the compressive residual stresses.

  • 40.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Gustafsson, M.
    Fatigue of high strength steel joints welded with low temperature transformation consumables2009In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 16, no 7, p. 2186-2194Article in journal (Refereed)
    Abstract [en]

    In the present paper constant (CA) and variable amplitude (VA) fatigue testing have been carried out on out-of plane gusset fillet welded high strength steel joints. The joints were welded with conventional weld filler material and martensitic low transformation temperature weld filler, LTT, in order to study the influence of the residual stress on the fatigue strength. Residual stress measurements were carried out close to the weld toe using X-ray diffraction technique in order to study the relaxation due to VA fatigue. The residual stress showed different level of relaxation depending on the VA spectrum loading used. The LTT joints show similar to 40% increase in mean fatigue strength compared to the conventional joints in CA The LTT joints show similar to 12% increase in mean fatigue strength compared to the conventional joints. The LTT joints show 33% increase in mean fatigue strength in CA compared to VA testing. However, the improvement of the fatigue strength is less significant in variable amplitude testing mainly due to the relaxation of the compressive residual stresses.

  • 41.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsson, B.
    Influence of weld quality on the fatigue strength in seam welds2011In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 18, no 3, p. 971-979Article in journal (Refereed)
    Abstract [en]

    In this paper a research study has been carried out on the link between weld quality of production welds and the fatigue strength. It has been carried out as a part of a Swedish Technology Platform for lightweight optimised welded structures (LOST), where some of the work packages within the project intend to connect the design and analysis to production and weld quality. One of the results is a new weld quality system from Volvo Group, which has a scientific background, is open for public use and focus on features important for fatigue in welded joints. In this study the emphasis is on a couple of features within the new weld quality system: weld toe radius and the possible existence of weld defects such as cold laps. Large scatter of the local weld geometry was observed for different welding processes. Also the results show that the weld position has a significant effect on the quality and the fatigue resistance of fillet welds and that it may be the difference between normal quality and high quality welds.

  • 42.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Jonsson, Bertil
    Volvo CE HL Divisions.
    Fatigue Assessment and LEFM Analysis of Cruciform Joints Fabricated with Different Welding Processes2008In: Welding in the World, ISSN 0043-2288, Vol. 52, no 7-8, p. 93-105Article in journal (Refereed)
    Abstract [en]

    In this study fatigue testing and defect assessment were carried out on specimens welded with robotic and manualwelding using fl ux cored (FCAW) and metal cored (MCAW) fi ller materials in order to study the effect of the weldingmethod on the fatigue strength and weld quality. Thirteen different batches were investigated of which two wasshot peened before fatigue testing. The local weld geometry was measured for all the specimens before testing.The specimens welded with fl ux cored weld wire showed the best fatigue strength, small defects and low residualstresses. Large scatter in the fatigue data is observed, especially when manual welding is employed. The few largestdefects were removed by the shot peening process, although small defects survived. This led to a smaller scatterin fatigue live for the shot peened specimens. Linear elastic fracture mechanics, LEFM, was employed for analysisof the fatigue test results. The fatigue life predictions using a 2D LEFM FE-model for simulating a continuous coldlap defect along the weld toe showed a qualitative agreement with the fatigue test results. The 2D analysis showedthat a continuous cold lap defect should be no more than 0.5 mm deep in order to comply with the requirement offatigue lives for normal weld quality according to the IIW design rules. For larger defects (> 0.8 mm) an increased toeradius will have a small effect on the fatigue strength. A 3D LEFM analysis of crack growth from a spatter-inducedcold lap defect was also carried out. This showed similar trends in crack growth compared to the 2D analysis ofa continuous cold lap, although the spatter-induced cold lap defect (semi-elliptical) had a longer fatigue life (x2.7),and hence is less dangerous from a fatigue point of view.

  • 43.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsson, Bertil
    Fatigue Assessment and LEFM Analysis of Cruciform Joints Fabricated with Different Welding Processes, XIII-2175-072007In: IIW International Institute of Welding: 60th Annual Assembly, 2007Conference paper (Other academic)
    Abstract [en]

    In this study fatigue testing and defect assessment were carried out on specimens welded with robotic and manualwelding using fl ux cored (FCAW) and metal cored (MCAW) fi ller materials in order to study the effect of the weldingmethod on the fatigue strength and weld quality. Thirteen different batches were investigated of which two wasshot peened before fatigue testing. The local weld geometry was measured for all the specimens before testing.The specimens welded with fl ux cored weld wire showed the best fatigue strength, small defects and low residualstresses. Large scatter in the fatigue data is observed, especially when manual welding is employed. The few largestdefects were removed by the shot peening process, although small defects survived. This led to a smaller scatterin fatigue live for the shot peened specimens. Linear elastic fracture mechanics, LEFM, was employed for analysisof the fatigue test results. The fatigue life predictions using a 2D LEFM FE-model for simulating a continuous coldlap defect along the weld toe showed a qualitative agreement with the fatigue test results. The 2D analysis showedthat a continuous cold lap defect should be no more than 0.5 mm deep in order to comply with the requirement offatigue lives for normal weld quality according to the IIW design rules. For larger defects (> 0.8 mm) an increased toeradius will have a small effect on the fatigue strength. A 3D LEFM analysis of crack growth from a spatter-inducedcold lap defect was also carried out. This showed similar trends in crack growth compared to the 2D analysis ofa continuous cold lap, although the spatter-induced cold lap defect (semi-elliptical) had a longer fatigue life (x2.7),and hence is less dangerous from a fatigue point of view.

  • 44.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Khurshid, Mansoor
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Cargotec Sweden AB.
    Ultimate Strength Capacity of Welded Joints in High Strength Steels2017In: 2nd International Conference on Structural Integrity, ICSI 2017 / [ed] Iacoviello, F Moreira, PMGP Tavares, PJS, Elsevier, 2017, Vol. 5, p. 1401-1408Conference paper (Refereed)
    Abstract [en]

    High strength steels are nowadays used in a wide range of weight lifting applications, e.g. spreaders and cranes, where there is a demand on lightweight design of these structures with increased structural performance where the welds become more sensitive to failure. This study focuses on investigating the influence of the mismatch in the yield strength of the weld filler material and the welds penetration depth on the ultimate strength capacity and failure modes of butt and fillet welded high strength steels of yield strength in the range of 350 960 MPa. The load carrying capacities of these mentioned joints are evaluated with experiments and compared with the estimations by finite element analysis (FEA), and design rules in Eurocode 3 and American Welding Society Code AWS D1.1. Fully penetrated joint with under-matched filler material is more ductile and the ultimate strength capacity of base plate can be achieved. It is observed that joints with under-matched filler material are more sensitive to penetration ratio. This influence is more pronounced in joints in S960 steel welded with under-matched filler material. It is also found that the design rules in Eurocode3 (valid for design of welded joints in steels of grade up to S700) can be extended to designing of welds in S960 steels using correlation factor of one.

  • 45.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Khurshid, Mansoor
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Barsoum, I.
    Fatigue strength evaluation of friction stir welded aluminium joints using the nominal and notch stress concepts2012In: Materials & Design, ISSN 0261-3069, Vol. 41, p. 231-238Article in journal (Refereed)
    Abstract [en]

    In this study the fatigue strength is investigated for Friction Stir Welded (FSW) overlap and butt welded joints in different thicknesses based on nominal and effective notch stress concepts. The fatigue test results are compared with fatigue strength recommendations according to EN 1999-1-3 and International Institute of Welding (IIW). The results are also compared with available published data and Finite Element Analysis (FEA) is carried out to investigate the effect of plate thickness and nugget size on the fatigue strength of overlap joints. 3-3 mm butt welded joints shows the highest fatigue strength in comparison with 3-5 mm butt welded and overlap joints. Slopes of the SN-curves for two different joint types differ from the slope recommended by IIW. A specific failure trend is observed in overlap FSW joints. However, the slopes of the SN-curves are in close agreement with slopes found in EN 1999-1-3. The slopes of various published results and test results presented in this study are in good agreement with each other. The suggested fatigue design curves for the nominal and effective notch stress concept have a higher slope than given for fusion welds by IIW.

  • 46.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Lundbäck, A.
    Luleå Univ Technol, Div Mat Mech.
    Simplified FE welding simulation of fillet welds: 3D effects on the formation residual stresses2009In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 16, no 7, p. 2281-2289Article in journal (Refereed)
    Abstract [en]

    In this study two- and three-dimensional finite element welding simulations have been carried out. The welded component studied is a T-type fillet weld which is frequently used in the heavy vehicle machine industry with plate thicknesses of eight and 20 mm, respectively. The software's used for the welding simulations is MSC.Marc and ANSYS. The objective is to study the formation of the residual stresses due to 3D effect of the welding process. Moreover, welding simulations using solid models and contact models in the un-fused weld roots were carried out in order to investigate the possible effect with respect to the residual stresses. Residual stress measurements were carried out using X-ray diffraction technique on the manufactured T-welded structure. The 2D residual stress predictions shows good agreement with measurements, hence the 2Dwelding simulation procedure is suitable for residual stress predictions for incorporation in further fatigue crack growth analysis from weld defects emanating from the weld toe and the un-fused root.

  • 47.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Samuelsson, Jack
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Fatigue and Quality Analysis of Cruciform Joints Welded with Different Methods, XIII-2136-062006In: International Institute of Welding: IIW 59th Annual Assembly, 2006Conference paper (Other academic)
  • 48.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Samuelsson, Jack
    Volvo Articulated Haulers AB.
    Fatigue Assessment of Cruciform Joints Welded with Different Methods2006In: Steel Research International, ISSN 1611-3683, Vol. 77, no 12, p. 882-888Article in journal (Refereed)
    Abstract [en]

    The advantages of the relatively new laser welding method are low welding distortions and high productivity, and it opens new opportunities for welding of steel structures in the automotive and heavy machinery industries. There is a need for understanding the fatigue strength and to develop fatigue design curves for laser welded joints. In this paper fatigue testing and weld quality of Hybrid Nd: YAG laser/MAG and MAG welded non-load carrying cruciform joints is examined. Four batches were produced, tested and the results were compared. The local weld geometry of the cruciform welded joints was measured and analysed. The measured parameters were used to calculate the stress concentration factors by implementing FE-models, in order to anticipate the influence of size of weld geometrical parameters on the stress concentrations. Residual stress measurement was carried out close to the toe region using the X-ray diffraction method and weld defects (cold laps) in the cracked specimens was measured.

  • 49.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Samuelsson, Jack
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Residual Stress Prediction and Relaxation in Welded Tubular Joints2006In: IIW Doc. No. XIII-2135-06/XV-1225-06, 2006Conference paper (Other academic)
  • 50.
    Barsoum, Zuheir
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Samuelsson, Jack
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Torsion Fatigue and Residual Stresses in Multi-Pass Welded Tubular Joint2005In: IIW Doc. No. XIII-2073-05, 2005Conference paper (Other academic)
12 1 - 50 of 96
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