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  • 151.
    Azhdar, Bruska
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Stenberg, Bengt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Polymer-nanofiller prepared by high-energy ball milling and high velocity cold compaction2008In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 29, no 3, p. 252-261Article in journal (Refereed)
    Abstract [en]

    High-energy ball milling using comilling in a solid state by low-temperature mechanical alloying to prepare nickel-ferrite (NiFe2O4) nanopowders and ultrafine poly(methyl methacrylate) (PMMA), dispersing nanoparticles in a polymer matrix, and a uniaxial high-velocity cold compaction process using a cylindrical, hardened steel die and a new technique with relaxation assists have been studied. The focus has been on the particle size distributions of the nanocomposite powder during the milling and on the surface morphology of the nanocomposite-compacted materials after compaction with and without relaxation assists. Experimental results for different milling systems are presented showing the effects of milling time and material ratio. It was found that a longer mixing time give a higher degree of dispersion of the nanopowder on the PMMA particle surfaces. Furthermore, with increasing content of NiFe2O4 nanopowder, the reduction of the particle size was more effective. Different postcompacting profiles, i.e. different energy distributions between the upper and lower parts of the compacted powder bed, lead to different movements of the various particles and particle layers. Uniformity, homogeneity, and densification on the surfaces in the compacted powder are influenced by the postcompacting magnitude and direction. It was found that the relaxation assist device leads to an improvement in the polymer powder compaction process by reducing the expansion of the compacted volume and by reducing the different opposite velocities, giving the compacted composite bed a more homogeneous opposite velocity during the decompacting stage and reducing the delay time between the successive pressure waves.

  • 152.
    Azizi Samir, M. A. S.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Alloin, F.
    Dufresne, A.
    High performance nanocomposite polymer electrolytes2006In: Composite interfaces (Print), ISSN 0927-6440, E-ISSN 1568-5543, Vol. 13, no 4-6, p. 545-559Article in journal (Refereed)
    Abstract [en]

    Solid lithium-conducting nanocomposite polymer electrolytes based on poly(oxyethylene) (POE) were prepared using high aspect ratio cellulosic whiskers and lithium imide salt, LiTFSI. The cellulosic whiskers were extracted from tunicate - a sea animal - and consisted of slender parallelepiped rods that have an average length around 1 μm and a width close to 15 nm. High performance nanocomposite electrolytes were obtained. The filler provided a high reinforcing effect, despite the favorable cellulose/POE interactions that were expected to decrease the possibility of interwhisker connection and formation of a percolating cellulosic network, while a high level of ionic conductivity was retained with respect to unfilled polymer electrolytes. Cross-linking and plasticizing of the matrix as well as preparation of the composites from an organic medium were also investigated.

  • 153.
    Azizi Samir, M. A. S.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. Université Joseph Fourier, France.
    Alloin, F.
    Dufresne, A.
    Review of recent research into cellulosic whiskers, their properties and their application in nanocomposite field2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, no 2, p. 612-626Article in journal (Refereed)
    Abstract [en]

    There are numerous examples where animals or plants synthesize extracellular high-performance skeletal biocomposites consisting of a matrix reinforced by fibrous biopolymers. Cellulose, the world's most abundant natural, renewable, biodegradable polymer, is a classical example of these reinforcing elements, which occur as whiskerlike microfibrils that are biosynthesized and deposited in a continuous fashion. In many cases, this mode of biogenesis leads to crystalline microfibrils that are almost defect-free, with the consequence of axial physical properties approaching those of perfect crystals. This quite "primitive" polymer can be used to create high performance nanocomposites presenting outstanding properties. This reinforcing capability results from the intrinsic chemical nature of cellulose and from its hierarchical structure. Aqueous suspensions of cellulose crystallites can be prepared by acid hydrolysis of cellulose. The object of this treatment is to dissolve away regions of low lateral order so that the water-insoluble, highly crystalline residue may be converted into a stable suspension by subsequent vigorous mechanical shearing action. During the past decade, many works have been devoted to mimic biocomposites by blending cellulose whiskers from different sources with polymer matrixes.

  • 154.
    Back, Robin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Optimeringsmetoder för ASMC-strukturer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Thin metal sheets have for long been the dominant structural components in automotive bodies, but as environmental concerns mount new materials are needed to reduce mass. Advanced Sheet Moulding Compounds (ASMC) is a carbon fibre composite with short fibres and has been put forward as an alternative. It is both light and has good durability and can be formed in a mould similarly to steel sheets. A distinct advantage is that unlike for steel sheets the thickness in an ASMC component can be varied and stiffeners integrated. This creates great opportunities for optimisation, but as know-how in the industry is scarce a methodology is necessary. This master’s thesis describes a method developed for optimising structural components manufactured in ASMC by analysing a backplate mounted in a Body-In-White (BIW). The optimisation design process was first developed in a simplified model made to mimic a BIW without all the complexities therein. In this thesis free-size optimisation was done individually and coupled with adding uni-directional (UD) fibres and ribs to the backplate. This process was then verified in an accurate car body model and the process translated rather well to a more realistic model as favourable results were obtained. Optimisation resulted in more than 50% decrease in the component’s mass and body torsional stiffness could be increased by up to 7%. A step-by-step guide for this process is presented. Moving forward the design methodology needs to be verified and developed further for different structures and load cases. It is believed that the process detailed works well for many different structures as is, but improvements can be made and are ultimately necessary.

  • 155.
    Backström, Daniel
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Estimation of the material parameters of a sandwich beam from measured eigenfrequenciesManuscript (Other academic)
  • 156.
    Backström, Daniel
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Vibration of sandwich beams2006Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Some aspects and properties of the lateral vibration of sandwich beams are investigated, including the concept of apparent bending stiffness and shear modulus, allowing the sandwich beam dynamics to be approximately described by classical beam theory. A sixth order beam model is derived including boundary conditions, and the free and forced response of some beam configurations analyzed. The possibility of computing material parameters from measured eigenfrequencies, i. e. inverse analysis, is considered. The higher order model is also utilized for investigation of the energy propagation through sandwich composite beams and the transmission over different junctions.

  • 157.
    Backström, Daniel
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Vibration transmission through sandwich composite beam junctionsManuscript (Other academic)
  • 158.
    Backström, Daniel
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Nilsson, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Flexural vibrations of a three-layer sandwich beam - Using ordinary fourth order beam theory in combination with frequency dependent parameters to predict the flexural dynamics of a sandwich beam2005In: Sandwich Structures7: Advancing with Sandwich Structures and Materials / [ed] Thomsen, OT; Bozhevolnaya, E; Lyckegaard, A, 2005, p. 567-575Conference paper (Refereed)
    Abstract [en]

    The purpose of this work has been 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 aluminium laminates and a plastic foam core, indicating good agreement.

  • 159.
    Backström, Daniel
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Nilsson, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Modelling the flexural vibration of a sandwich beam using modified timoshenko theory2005In: 12th International Congress on Sound and Vibration 2005: ICSV 2005, 2005, p. 4944-4951Conference paper (Refereed)
    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.

  • 160.
    Backström, Daniel
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Nilsson, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Some properties of the energy flow corresponding to flexural waves in sandwich beam structures2006In: EURONOISE 2006 - The 6th European Conference on Noise Control: Advanced Solutions for Noise Control, 2006, p. 7P-Conference paper (Refereed)
    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.

  • 161.
    Backström, Daniel
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Nilsson, Anders Christian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Modelling the vibration of sandwich beams using frequency dependent parameters2007In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 300, no 3-5, p. 589-611Article in journal (Refereed)
    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.

  • 162.
    Backstöm, Daniel
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Nilsson, Anders
    Modeling flexural vibration of a sandwich beam using modified fourth-order theory2006In: Journal of Sandwich Structures and Materials, ISSN 1099-6362, E-ISSN 1530-7972, Vol. 8, no 6, p. 465-476Article in journal (Refereed)
    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.

  • 163.
    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, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Photovoltaic Systems with Rotational Panels to Harvest Natural and Artificial Light for Electrical Production2018In: 2018 5TH INTERNATIONAL CONFERENCE ON ELECTRICAL AND ELECTRONIC ENGINEERING (ICEEE), IEEE , 2018, p. 211-214Conference paper (Refereed)
    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.

  • 164.
    Ballard, Claire
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Conceptual lay-out of small launcher2012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 165. Balmer, G.
    et al.
    Berquand, A.
    Company-Vallet, E.
    Granberg, V.
    Grigore, V.
    Ivchenko, Nickolay
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Kevorkov, R.
    Lundkvist, E.
    Olentsenko, Georgi
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Pacheco-Labrador, J.
    Tibert, Gunnar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Yuan, Yunxia
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    ISAAC: A REXUS STUDENT EXPERIMENT TO DEMONSTRATE AN EJECTION SYSTEM WITH PREDEFINED DIRECTION2015In: EUROPEAN ROCKET AND BALLOON: PROGRAMMES AND RELATED RESEARCH, 2015, p. 235-242Conference paper (Refereed)
    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.

  • 166.
    Bangalore Gangadharacharya, Koushik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Vortex Shedding And Aerodynamic Drag On Truncated Trailing Edge Airfoil2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 167.
    Barbagallo, Mathias
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Statistical energy analysis and variational principles for the prediction of sound transmission in multilayered structures2013Doctoral thesis, comprehensive summary (Other academic)
    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.

  • 168.
    Barbagallo, Mathias
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    A natural variational principle for Biot's equation: Waveguide FE and SEA of multilayered structures comprising porous materials2011Conference paper (Other academic)
  • 169.
    Barbagallo, Mathias
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    A self-adjoint variational principle for anisotropic viscoelastic Biot’s equations2013In: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197, Vol. 63, p. 71-83Article in journal (Refereed)
    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.

  • 170.
    Barbagallo, Mathias
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Characterisation of a generic trim-panel: sound reduction index and material parameters2013Report (Other academic)
  • 171.
    Barbagallo, Mathias
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Spatial energy decay and indirect couplings in statistical energy analysis2010Conference paper (Other academic)
    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.

  • 172.
    Barbagallo, Mathias
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Liu, Hao
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Statistical energy analysis of the sound transmission through layered panels using a variational formulation of the porous materialArticle in journal (Other academic)
  • 173.
    Bardet, Valentine
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Automation of inserts-checking on an Aluminiumsandwich structure2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 174.
    Barmicho, Ilona
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Fatigue Life Assessment of Cut Edges in High Strength Steel2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 175.
    Barmicho, Ilona
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Load bearing Composite Beam in a Bus Structure2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 176. Baro, S.
    et al.
    Corradi, R.
    Åbom, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Tyre cavity noise: Porous materials as a countermeasure2016In: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future, German Acoustical Society (DEGA) , 2016, p. 2313-2318Conference paper (Refereed)
    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.

  • 177.
    Baro, Simone
    et al.
    Politecn Milan, Dept Mech Engn, Milan, Italy..
    Corradi, Roberto
    Politecn Milan, Dept Mech Engn, Milan, Italy..
    Åbom, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Caracino, Paola
    Pirelli Tyre, Milan, Italy..
    Fioravanti, Anna Paola
    Pirelli Tyre, Milan, Italy..
    Modelling of a lined tyre for predicting cavity noise mitigation2019In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 155, p. 391-400Article in journal (Refereed)
    Abstract [en]

    Tyre cavity resonance can significantly affect vehicle interior noise at frequencies around 200 Hz. The insertion of a sound absorbing liner inside the tyre is known to be an efficient countermeasure, in fact nowadays tyre manufacturers are already producing tyres implementing this kind of solution. The present work, through analytical and numerical models, supported by material testing, provides a methodology for predicting the dag performance of a lined tyre, taking into account tyre/lining geometry and sound absorbing material properties. The results reported in the paper show that for fixed material characteristics, the attenuation of the cavity resonance is mostly influenced by the volume of the lining treatment. Moreover, the numerical model developed for discontinuous treatments, suggests that for fixed volume and material properties, the cavity resonance attenuation can be increased by choosing a proper layout. Elsevier Ltd. All rights reserved.

  • 178.
    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, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. 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 problems2007In: 36th International Congress and Exposition on Noise Control Engineering, INTER-NOISE, 2007, Vol. 7, p. 4796-4805Conference paper (Other academic)
    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. 

  • 179.
    Barrére, Vincent
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Viability of CREO Simulate: (CAD software’s module) as a thermal simulation software2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The analysis of the reliability of CREO simulate will be done step by step. First of all, the precisionof the simulation has to be measured thus a comparison with simple theoretical computations willbe done. Then, the scope of the capacity of the software will be analyzed and if elements deemednecessary to thermal simulations are missing, back up solutions are to be found. Also, the influenceof the meshing will be studied and measured to ensure that the software guarantee convergence evenin the hand of persons unfamiliar with simulations.In parallel, one will experiment with realistic hardware that could be used to compare reality withthe simulations. Those experiments will be handmade using regular materials from the company.

  • 180.
    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.

  • 181. 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.

  • 182.
    Barsoum, IImad
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. Petr Inst, U Arab Emirates.
    Al Ali, K. F.
    A procedure to determine the tangential true stress-strain behavior of pipes2015In: International Journal of Pressure Vessels and Piping, ISSN 0308-0161, E-ISSN 1879-3541, Vol. 128, p. 59-68Article in journal (Refereed)
    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.

  • 183.
    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.))
  • 184.
    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)
  • 185.
    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)
  • 186.
    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)
  • 187.
    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.

  • 188.
    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)
  • 189.
    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.

  • 190.
    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.))
  • 191.
    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)
  • 192.
    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)
  • 193.
    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.

  • 194.
    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.

  • 195.
    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.

  • 196.
    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.

  • 197.
    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.

  • 198.
    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.

  • 199.
    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)
  • 200.
    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)
1234567 151 - 200 of 3049
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