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  • 151.
    Backström, Daniel
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Nilsson, Anders
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Modelling the flexural vibration of a sandwich beam using modified timoshenko theory2005Inngår i: 12th International Congress on Sound and Vibration 2005: ICSV 2005, 2005, s. 4944-4951Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The flexural vibration of an asymmetric sandwich beam is modelled using Timoshenko theory with frequency dependent parameters. The advantage of this approach, as compared to using modified Bernoulli-Euler theory, is the independence of the frequency dependent parameters on the boundary conditions of the beam. Using Bernoulli-Euler theory, the apparent bending stiffness would have to depend on the particular end conditions of the beam configuration in order to achieve the best possible accuracy. Using instead Timoshenko theory, with frequency dependent bending stiffness and shear modulus parameters, this problem is avoided. The results are compared to measurements and to the results obtained from a previously derived 6th order sandwich beam theory, which takes into account the effects of pure bending of the entire beam, core shear and its coupling to the bending of the laminates, and rotational inertia. The possibility of implementing the approach in existing Timoshenko beam elements in commercial FEM programs is discussed.

  • 152.
    Backström, Daniel
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Nilsson, Anders
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Some properties of the energy flow corresponding to flexural waves in sandwich beam structures2006Inngår i: EURONOISE 2006 - The 6th European Conference on Noise Control: Advanced Solutions for Noise Control, 2006, s. 7P-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The energy flow corresponding to the propagation of flexural waves in sandwich beam structures is investigated. A previously derived 6th order theory describing the bending of sandwich beams is utilized and important properties such as group velocity and energy transmission through joints are analyzed and compared to those expected from classical beam theory. The results could be applied in the method of statistical energy analysis (SEA) in order to predict the vibration level of different members of composite structures composing sandwich beam elements.

  • 153.
    Backström, Daniel
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Nilsson, Anders Christian
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Modelling the vibration of sandwich beams using frequency dependent parameters2007Inngår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 300, nr 3-5, s. 589-611Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Various types of sandwich beams with foam or honeycomb cores are currently used in the industry, indicating the need for simple methods describing the dynamics of these complex structures. By implementing frequency-dependent parameters, the vibration of sandwich composite beams can be approximated using simple fourth-order beam theory. A higher-order sandwich beam model is utilized in order to obtain estimates of the frequency-dependent bending stiffness and shear modulus of the equivalent Bernoulli-Euler and Timoshenko models. The resulting predicted eigenfrequencies and transfer accellerance functions are compared to the data obtained from the higher-order model and from measurements.

  • 154.
    Backstöm, Daniel
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Nilsson, Anders
    Modeling flexural vibration of a sandwich beam using modified fourth-order theory2006Inngår i: Journal of Sandwich Structures and Materials, ISSN 1099-6362, E-ISSN 1530-7972, Vol. 8, nr 6, s. 465-476Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study is to evaluate the possibility of using modified lower order methods - such as the Bernoulli-Euler or Timoshenko beam theories with frequency dependent parameters - to calculate the response of sandwich beams subject to different end conditions. The models have been verified by measurements on a freely suspended asymmetric sandwich beam with aluminum laminates and a plastic foam core, indicating good agreement.

  • 155.
    Bagheritabar, Mahmoud
    et al.
    Islamic Azad Univ, North Tehran Branch, Elect & Comp Engn Dept, Tehran, Iran..
    Bagheitabar, Hamed
    Islamic Azad Univ, Damavand Branch, Dept Elect & Energy Engn, Tehran, Iran..
    Kashani, Mohammad Mansour Riahi
    Islamic Azad Univ, North Tehran Branch, Elect & Comp Engn Dept, Tehran, Iran..
    Khodashenas, Niloofar Sayyad
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Photovoltaic Systems with Rotational Panels to Harvest Natural and Artificial Light for Electrical Production2018Inngår i: 2018 5TH INTERNATIONAL CONFERENCE ON ELECTRICAL AND ELECTRONIC ENGINEERING (ICEEE), IEEE , 2018, s. 211-214Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Regarding the fact that huge amount of non-renewable energy is extracted, distributed, converted and consumed for electrical demands in the Building-Integrated Photovoltaic systems, using the rotational photovoltaic panels as a source of energy would be more convenient. Optimization of this system which harvests outdoor natural light and indoor artificial light is an enormous need to maximize the solar panel efficiency. In this paper to achieve the main purpose, an experimental attempt has been made to model the wall and window built PV system as economical as possible. The performance of this model is carried out on the facade of buildings with a Manual switch for rotation. The result of this experiment has shown that the system is more efficient.

  • 156.
    Ballard, Claire
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Conceptual lay-out of small launcher2012Independent thesis Advanced level (degree of Master (Two Years)), 30 poäng / 45 hpOppgave
  • 157. Balmer, G.
    et al.
    Berquand, A.
    Company-Vallet, E.
    Granberg, V.
    Grigore, V.
    Ivchenko, Nickolay
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Kevorkov, R.
    Lundkvist, E.
    Olentsenko, Georgi
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Pacheco-Labrador, J.
    Tibert, Gunnar
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Yuan, Yunxia
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    ISAAC: A REXUS STUDENT EXPERIMENT TO DEMONSTRATE AN EJECTION SYSTEM WITH PREDEFINED DIRECTION2015Inngår i: EUROPEAN ROCKET AND BALLOON: PROGRAMMES AND RELATED RESEARCH, 2015, s. 235-242Konferansepaper (Fagfellevurdert)
    Abstract [en]

    ISAAC - Infrared Spectroscopy to Analyse the middle Atmosphere Composition was a student experiment launched from SSC's Esrange Space Centre, Sweden, on 29th May 2014, on board the sounding rocket REXUS 15 in the frame of the REXUS/BEXUS programme. The main focus of the experiment was to implement an ejection system for two large Free Falling Units (FFUs) (240 mm x 80 mm) to be ejected from a spinning rocket into a predefined direction. The system design relied on a spring-based ejection system. Sun and angular rate sensors were used to control and time the ejection. The flight data includes telemetry from the Rocket Mounted Unit (RMU), received and saved during flight, as well as video footage from the GoPro camera mounted inside the RMU and recovered after the flight. The FFUs' direction, speed and spin frequency as well as the rocket spin frequency were determined by analyzing the video footage. The FFU-Rocket-Sun angles were 64.3 degrees and 104.3 degrees, within the required margins of 90 degrees +/- 45 degrees. The FFU speeds were 3.98 m/s and 3.74 m/s, lower than the expected 5 +/- 1 m/s. The FFUs' spin frequencies were 1.38 Hz and 1.60 Hz, approximately half the rocket's spin frequency. The rocket spin rate slightly changed from 3.163 Hz before the ejection to 3.117 Hz after the ejection of the two FFUs. The angular rate, sun sensor data and temperature on the inside of the rocket module skin were also recorded. The experiment design and results of the data analysis are presented in this paper.

  • 158.
    Bangalore Gangadharacharya, Koushik
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Flygdynamik.
    Vortex Shedding And Aerodynamic Drag On Truncated Trailing Edge Airfoil2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The thesis work content is to evaluate the use of more advanced turbulence models available in the ANSYS CFX software for aerodynamic calculations. In particular for flows over airfoils with thick trailing edges, the turbulence modeling is challenging to traditional methods, as both thin boundary layers as well as an unsteady wake needs to be well represented. This is done by using the standard SST and then performing unsteady computations using the more advanced unsteady SAS-SST model to get the relevant CFD results. By comparing to tests performed at GKN and results from literature the improvement could be assessed in terms of modeling quality and computational cost. The results presented give a good contribution to how the modeling of unsteady wakes can be improved and used for design purposes.

  • 159.
    Barbagallo, Mathias
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Statistical energy analysis and variational principles for the prediction of sound transmission in multilayered structures2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Multilayered structures have many application in industry and society: they have peculiar properties and serve a variety of purposes, like structural support, thermal insulation, vibrational and acoustic isolation. This thesis concerns the prediction of sound transmission in multilayered structures. Two problems are herein investigated: the transmission of energy through structures and the transmission of energy along structures. The focus of the analysis is on the mid to high frequency range. To predict sound transmission in these structures, statistical energy analysis (SEA) is used.SEA models are devised for the prediction of the sound reduction index for two kinds of multilayered structures, double-walls used in buildings and trim-panels in vehicles; the double-walls comprise an air cavity in between flat plasterboard or glass plates, whereas the trim-panels a porous layer in between curved aluminium and rubber layers. The SEA models are based upon the wave-types carrying energy. The novelty in these SEAs is an element describing the waves in the air cavity, or in the porous layer, fully coupled to the mass-impeded external layers. Compared to measurements, the proposed SEA performs well: for double-walls, it performs better than previous models; for trim-panels, it is an original result. The parameters of the new SEA element, such as modal density, are derived from the coupling equations describing the fully coupled waves. For double-walls, these equations are derived via Newton's laws. For trim-panels, a variational approach based upon a modified Hamilton's principle valid for non-conservative systems is preferred, because it is a powerful machinery for deriving equations of motion and coupling conditions of a medium as complex as the porous layer. The modified Hamilton's principle for non-conservative systems is based upon a self-adjoint functional analogous to the Lagrangian, inspired by Morse and Feshbach's construction. A self-adjoint variational principle for Biot's equations in the displacement formulation is devised. An equivalent mixed formulation is obtained changing the coordinates of the displacement formulation via Lagrange multipliers. From this mixed formulation, the Lagrangian for a porous material with a limp frame is derived, which yields the continuity of the total displacement of the porous layer. Lagrange multipliers help to obtain the correct coupling functionals between a porous material and a solid. The Lagrange multipliers introducing the continuity of the frame and the solid displacements equal the traction of the in-vacuo frame, thus disappearing if the latter is limp. Measurements to gather material parameters for a Biot model of the porous layer have been conducted.The effects of spatial energy decay in the transmission along structures predicted by SEA is studied: a major effect is the increased relevance of indirect coupling loss factors between SEA elements. This may jeopardize the usefulness of SEA at higher frequencies.

  • 160.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    A natural variational principle for Biot's equation: Waveguide FE and SEA of multilayered structures comprising porous materials2011Konferansepaper (Annet vitenskapelig)
  • 161.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    A self-adjoint variational principle for anisotropic viscoelastic Biot’s equations2013Inngår i: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197, Vol. 63, s. 71-83Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A variational principle for anisotropic viscoelastic Biot’s equations of motion is presented. It is based upon an extended Hamilton’s principle, also valid for dissipative systems. Using this principle, a functional analogous to the Lagrangian is defined, starting from Biot’s variational formulation based on frame and fluid displacements. Then, a mixed displacement–pressure formulation is presented, which reduces the number of variables of response from six to four. The corresponding functional analogous to the Lagrangian is derived making full use of variational calculus. The derived functionals are self-adjoint and stationary for true motion.

  • 162.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Characterisation of a generic trim-panel: sound reduction index and material parameters2013Rapport (Annet vitenskapelig)
  • 163.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Spatial energy decay and indirect couplings in statistical energy analysis2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Spatial energy decay within elements affects the validity of SEA. This is particularly significant for chains of similar long well-connected structures such as ventilation ducts, fluid-filled pipes and rib-stiffened plates found in ships, aircraft and railway cars. The effects of spatial energy decay on the high frequency response of one-dimensional well-connected elements are herein studied by comparing calculations by an SEA, a spectral finite element method and an SEA-like model. An SEA only includes direct coupling loss factors (CLFs); conversely, an SEA-like model also contains indirect CLFs. At high frequencies, the spatial energy decay increases and SEA overestimates the energies in all elements away from the excitation. Moreover, the indirect CLFs in the SEA-like model have to be considered when evaluating the energy flows, as the accumulated spatial decay from the excitation to the observed point increases. Thus, SEA cannot predict the high frequency response of similar long well-connected elements and alternative formulations are needed.

  • 164.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Liu, Hao
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Statistical energy analysis of the sound transmission through layered panels using a variational formulation of the porous materialArtikkel i tidsskrift (Annet vitenskapelig)
  • 165.
    Bardet, Valentine
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Automation of inserts-checking on an Aluminiumsandwich structure2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In space projects, checking inserts can be tedious, even more so for high density of inserts. This paper deals with the development of an automation tool for insert checking. All the principles used to perform inserts calculations are based on the ECSS-Design Handbook [1]. Those principles are summarised and adapted to the tool. The tool requires only a point cloud extracted from a CADmodel giving the position of inserts to be checked and the loads calculated thanks to an FEM-model at those same points to calculate safety margins. This paper details the process followed by the tool to calculate inserts strength and describes possible measures for improvements.

  • 166.
    Barmicho, Ilona
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Fatigue Life Assessment of Cut Edges in High Strength Steel2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The interests in more effective and lighter structures have increased the use of high strength steels for higher performances. Plate materials are optimized so thinner structures and higher material strengths are reached, this leads to the cut quality might be a new issue.

    In this investigation steel thickness of 6 and 16 mm with minimum yield strength from 355 to 960 MPa are fatigue tested with constant amplitude tensile loading. The specimens were cut using waterjet and also with thermally cut methods such as plasma and oxygen. Before fatigue testing the cut surfaces were measured and roughness Rz values were obtained.

    Empirical and analytical results of the surface roughness influencing the fatigue strength for different steel strengths are presented.

    Since thermal cutting methods have been developed over the years the FAT values are higher for those IIW are recommending.

    When the quality of the cut surface can be kept high the fatigue strength will also be higher than those recommended. This means having a cutting process that provides smooth surfaces such as waterjet and plasma cutting the fatigue life will be longer.

  • 167.
    Barmicho, Ilona
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Load bearing Composite Beam in a Bus Structure2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 168. Baro, S.
    et al.
    Corradi, R.
    Åbom, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Tyre cavity noise: Porous materials as a countermeasure2016Inngår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future, German Acoustical Society (DEGA) , 2016, s. 2313-2318Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The first resonance of the tyre air cavity can significantly affect vehicle interior noise at frequencies around 200 Hz. The insertion of a sound absorbing liner inside a tyre is known to be an efficient countermeasure to this problem and tyre manufacturers are already producing tyres implementing this solution. The present work proposes a methodology for predicting the damping performance of a lined tyre by means of numerical models. The geometry of the tyre cavity and the lining, as well as the properties of the sound absorbing material are taken into account and predictions are made concerning the effect of specific combinations of volume and properties of the liner. For fixed material characteristics, the volume of the lining treatment strongly influences the attenuation of the cavity resonance. Moreover, the simulations performed suggest that for fixed volume and material properties, larger attenuation of the cavity resonance peak can be obtained by adopting a discontinuous layout.

  • 169.
    Barrera Rolla, Leandro
    et al.
    Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland .
    Rice, Henry J.
    Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland.
    O'Reilly, Ciarán J.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Trinity College Dublin, Department of Mechanical and Manufacturing Engineering, Ireland.
    Implementation of the forward-advancing wave expansion method (FWEM) for numerical solution of three dimensional large-scale sound propagation problems2007Inngår i: 36th International Congress and Exposition on Noise Control Engineering, INTER-NOISE, 2007, Vol. 7, s. 4796-4805Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this paper a “one-way” wave based field discretization method for solving the Helmholtz equation in large-scale problems is proposed and is referred to as the Forward Wave Expansion Method (FWEM). The FWEM is derived from a highly efficient discretization procedure based on the interpolation of wave functions known as the Wave Expansion Method (WEM) and computes the propagated sound field by means of an exclusively forward advancing solution. This technique does not require the inversion of large system matrices and thus enables the solution of large scale acoustic problems where backscatter is not of interest. A computationally light model is thus formulated which retains many advantages of WEM. Accurate results were obtained for a free field sound propagation benchmarking problem. The method was also implemented to successfully model some diffraction effects. The FWEM offers a simple, flexible and efficient discretization method to solve the Helmholtz equation for extensive domains with mesh densities as low as 3 nodes per wavelength. This makes the FWEM a promising method for long range sound propagation problems. 

  • 170. Barsoum, I.
    et al.
    Khan, F.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Analysis of the torsional strength of hardened splined shafts2014Inngår i: Materials and Design, ISSN 0261-3069, Vol. 54, s. 130-136Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 171.
    Barsoum, IImad
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. Petr Inst, U Arab Emirates.
    Al Ali, K. F.
    A procedure to determine the tangential true stress-strain behavior of pipes2015Inngår i: International Journal of Pressure Vessels and Piping, ISSN 0308-0161, E-ISSN 1879-3541, Vol. 128, s. 59-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Determining the tangential mechanical properties of a tube is essential for simulation of various manufacturing processes that involve the use of a tubular geometry. The aim of this study is to develop a procedure to determine the tangential true stress-strain behavior of pipes. For this purpose a modified ring test setup is proposed consisting of a ring specimen loaded with two separate D-blocks. Using a finite element model, an optimized ring specimen geometry is obtained. The optimized ring specimen exhibits uniform tangential distribution in the gauge region of the specimen and necking occurs consistently at the center of the gauge length. It is found that friction has a substantial effect on the mechanical response of the ring test for which two different setups to reduce friction are proposed. One using lubricated D-blocks (DB) and one using lubricated D-blocks with needle roller bearing (RB). Assisted by the FE model, the friction during the experiment is account for and a data analysis procedure to determine the tangential stress-strain curve of the pipe is proposed. It is found that the results using this procedure show very good agreement with previously published results.

  • 172.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Avancerade metoder för noggrannare dimensionering av svetsade konstruktioner2009Inngår i: Svetsen, ISSN 0039-7091, Vol. 68, nr 3Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 173.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Fatigue Assessment of Cruciform Joints Welded with Different Methods2005Inngår i: IIW Doc. No. XIII-2074-05, 2005Konferansepaper (Annet vitenskapelig)
  • 174.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Fatigue design of welded structures: effect of weld quality and residual stresses, XIII-2312-102010Konferansepaper (Annet vitenskapelig)
  • 175.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Fatigue Strength of cruciform joints fabricated with different welding processes2007Inngår i: International Symposium on Integrated Design and Manufacturing of Welded Structures, Eskilstuna, 2007Konferansepaper (Annet vitenskapelig)
  • 176.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    HENRY GRANJON PRIZE COMPETITION 2010 Winner Category C: "Design and Structural Integrity" FATIGUE DESIGN OF WELDED STRUCTURES - SOME ASPECTS OF WELD QUALITY AND RESIDUAL STRESSES2011Inngår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 55, nr 11-12, s. 2-11Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 177.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Local weld geometry and the influence on fatigue strength2010Inngår i: Proceedings of the Swedish Conference on Lightweight Optimised Welded Structures: Borlänge, March 24-25, 2009 / [ed] Zubeir Barsoum, Jack Samuelsson, Borlänge, 2010, s. 26-38Konferansepaper (Annet vitenskapelig)
  • 178.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Numerical Analysis and Measurement of Residual Stresses in Multi Pass Welding - Influence on Fatigue Root Crack Propagation2006Inngår i: TRENDS IN WELDING RESEARCH, PROCEEDINGS / [ed] David SA; DebRoy T; Lippold JC; Smartt HB; Vitek JM, MATERIALS PARK: ASM INTERNATIONAL , 2006, s. 589-594Konferansepaper (Fagfellevurdert)
    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.

  • 179.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Ny doktorsavhandling: Restspännings- och utmattningsanalyser av svetsade stålkonstruktioner2008Inngår i: Svetsen, ISSN 0039-7091, Vol. 67, nr 3Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 180.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Prediction of Welding Residual Stresses2007Inngår i: International Symposium on Integrated Design and Manufacturing of Welded Structures, Eskilstuna, 2007Konferansepaper (Annet vitenskapelig)
  • 181.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Prediction of welding residual stresses by simplified approaches2010Inngår i: 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, s. 39-50Konferansepaper (Annet vitenskapelig)
  • 182.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Residual Stress Analysis and Fatigue Assessment of Welded Steel Structures2008Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • 183.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Residual Stress Analysis and Fatigue of Multi-pass Welded Tubular Structures2008Inngår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 15, nr 7, s. 863-874Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 184.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Residual Stress Analysis and Fatigue of Welded Structures2006Licentiatavhandling, med artikler (Annet vitenskapelig)
    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.

  • 185.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Residual stress predictin and relaxation in welded tubular joints under constant cyclic loading2006Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 524-525, s. 323-330Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 186.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Residual Stress Prediction and Relaxation in Welded Tubular Joint2007Inngår i: Welding in the World, ISSN 0043-2288, Vol. 51, nr 1/2, s. 23-30Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 187.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Residual stress prediction and relaxation in welded tubular joints under constant cyclic loading2006Inngår i: Residual Stresses VII / [ed] Reimers, W; Quander, S, 2006, Vol. 524-525, s. 323-328Konferansepaper (Fagfellevurdert)
    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.

  • 188.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Barsoum, Imad
    Residual stress effects on fatigue life of welded structures using LEFM2008Konferansepaper (Fagfellevurdert)
  • 189.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Barsoum, Imad
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Residual stress effects on fatigue life of welded structures using LEFM2009Inngår i: IIW International Institute of Welding: 62nd AnnualAssembly, 2009Konferansepaper (Annet vitenskapelig)
  • 190.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Barsoum, Imad
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Residual stress effects on fatigue life of welded structures using LEFM2009Inngår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 16, nr 1, s. 449-467Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 191.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Khalifa University.
    Bhatti, Ayjwat
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Balawi, S.
    Computational Weld Mechanics - Towards a Simplified and Cost Effective Approach for Large Welded Structures2015Inngår i: Procedia Engineering, 2015, s. 62-69Konferansepaper (Fagfellevurdert)
    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.

  • 192.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Khalifa University.
    Ghanadi, M.
    Balawi, S.
    Managing Welding Induced Distortion - Comparison of Different Computational Approaches2015Inngår i: Procedia Engineering, Elsevier, 2015, s. 70-77Konferansepaper (Fagfellevurdert)
    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.

  • 193.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Gustafson, Mats
    Spectrum fatigue of high strength steel joints welded with low temperature transformation consumables2007Inngår i: 2nd International Conference on Fatigue Design, 2007Konferansepaper (Fagfellevurdert)
    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.

  • 194.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Gustafsson, M.
    Fatigue of high strength steel joints welded with low temperature transformation consumables2009Inngår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 16, nr 7, s. 2186-2194Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 195.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Jonsson, B.
    Influence of weld quality on the fatigue strength in seam welds2011Inngår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 18, nr 3, s. 971-979Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 196.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Jonsson, Bertil
    Volvo CE HL Divisions.
    Fatigue Assessment and LEFM Analysis of Cruciform Joints Fabricated with Different Welding Processes2008Inngår i: Welding in the World, ISSN 0043-2288, Vol. 52, nr 7-8, s. 93-105Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 197.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Jonsson, Bertil
    Fatigue Assessment and LEFM Analysis of Cruciform Joints Fabricated with Different Welding Processes, XIII-2175-072007Inngår i: IIW International Institute of Welding: 60th Annual Assembly, 2007Konferansepaper (Annet vitenskapelig)
    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.

  • 198.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Khurshid, Mansoor
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Cargotec Sweden AB.
    Ultimate Strength Capacity of Welded Joints in High Strength Steels2017Inngår i: 2nd International Conference on Structural Integrity, ICSI 2017 / [ed] Iacoviello, F Moreira, PMGP Tavares, PJS, Elsevier, 2017, Vol. 5, s. 1401-1408Konferansepaper (Fagfellevurdert)
    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.

  • 199.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Khurshid, Mansoor
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Barsoum, I.
    Fatigue strength evaluation of friction stir welded aluminium joints using the nominal and notch stress concepts2012Inngår i: Materials & Design, ISSN 0261-3069, Vol. 41, s. 231-238Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 200.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Lundbäck, A.
    Luleå Univ Technol, Div Mat Mech.
    Simplified FE welding simulation of fillet welds: 3D effects on the formation residual stresses2009Inngår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 16, nr 7, s. 2281-2289Artikkel i tidsskrift (Fagfellevurdert)
    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.

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