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  • 301.
    Bjurhager, Ingela
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Gamstedt, E. KristoferUppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Predicting creep rate in archeological wood from theVasa ship – a first appraoch2012Konferanseproceedings (Fagfellevurdert)
  • 302.
    Bjurhager, Ingela
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Gamstedt, Kristofer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Keunecke, Daniel
    Niemz, Peter
    Berglund, Lars A.
    Mechanical performance of yew (Taxus baccata L.) from a longbow perspective2013Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 67, nr 7, s. 763-770Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Yew (Taxus baccata L.) longbow was the preferred weapon in the Middle Ages until the emergence of guns. In this study, the tensile, compression, and bending properties of yew were investigated. The advantage of yew over the other species in the study was also confirmed by a simple beam model. The superior toughness of yew has the effect that a yew longbow has a higher range compared with bows made from other species. Unexpectedly, the mechanical performance of a bow made from yew is influenced by the juvenile-to-mature wood ratio rather than by the heartwood-to-sapwood ratio. A yew bow is predicted to have maximized performance at a juvenile wood content of 30-50%, and located at the concave side (the compressive side facing the bowyer). Here, the stiffness and yield stress in compression should be as high as possible.

  • 303.
    Bjurhager, Ingela
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Vorobyev, AlexeyUppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.van Dijk, NicoUppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.Gamstedt, E. KristoferUppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.Ahlgren, AndersOlofsson, Magnus
    Investigation of time-dependent deformation of wood from the warship Vasa2013Konferanseproceedings (Fagfellevurdert)
  • 304.
    Blanchard, Pierre
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Residual stresses and indentation.2011Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The correlatioin between residual stresses and the global properties from an indentation test, i.e. hardness and size of the contact area, has been studied frequently in recent years. The investigations presented have been based on experimental, theoretical and numerical methods and as a result, the basic features of the problem are fairly well understood in the case of residual equi-biaxial surface stresses. The more general case, when the principal surface stresses are not necessarily equi-biaxial, has received nuch less attention and it is therefore the aim of the present study to remedy this shortcoming. In doing so, qualitative results are of immediate interest in this initial study but possible ways of quantitative descriptions are also discussed for future purposes. The present analysis is based on numerical methods and in particular the finite element method (FEM) is relied upon. Classical Mises elastoplastic material behavior is assumed throughout the investigation.

  • 305.
    Blanco, Blas
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. University of Navarra, Spain.
    Alonso, A.
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Gil-Negrete, N.
    Gimenez, J. G.
    Distributed support modelling for vertical track dynamic analysis2018Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 56, nr 4, s. 529-552Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The finite length nature of rail-pad supports is characterised by a Timoshenko beam element formulation over an elastic foundation, giving rise to the distributed support element. The new element is integrated into a vertical track model, which is solved in frequency and time domain. The developed formulation is obtained by solving the governing equations of a Timoshenko beam for this particular case. The interaction between sleeper and rail via the elastic connection is considered in an analytical, compact and efficient way. The modelling technique results in realistic amplitudes of the pinned-pinned' vibration mode and, additionally, it leads to a smooth evolution of the contact force temporal response and to reduced amplitudes of the rail vertical oscillation, as compared to the results from concentrated support models. Simulations are performed for both parametric and sinusoidal roughness excitation. The model of support proposed here is compared with a previous finite length model developed by other authors, coming to the conclusion that the proposed model gives accurate results at a reduced computational cost.

  • 306.
    Blom, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    A non-linear constitutive audio frequency magneto-sensitive rubber model including amplitude, frequency and magnetic field dependence.2011Inngår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 330, nr 5, s. 947-954Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel constitutive model of magneto-sensitive rubber in the audible frequency range is presented. Characteristics inherent to magneto-sensitive rubber within this dynamic regime are defined: magnetic sensitivity, amplitude dependence, elasticity and viscoelasticity. Prior to creating the model assumptions based on experimental observations concerning these components are formulated. The first observation is that not only does the rubber display a strong amplitude dependence even for small strains, but also the magnetic sensitivity is strongly amplitude dependent. The second and third are, respectively, that the elastic component is magneto-sensitive, whereas the viscoelastic dependence on magnetic induction appears to be small. Thus, the model is developed from these assumptions and parameters are optimized with respect to experimental values for one case and subsequently validated for others; a very good agreement is obtained.

  • 307.
    Blom, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Amplitude and frequency dependence of magneto-sensitive rubber in a wide frequency range2005Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 24, nr 5, s. 656-662Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new aspects of the dynamic behaviour in the audible frequency range of magneto-sensitive (MS) rubber are highlighted: the existence of an amplitude dependence of the shear modulus - referred to as the Fletcher-Gent effect - for even small displacements, and the appearance of large MS effects. In order to illustrate these two features, results are presented of measurements performed in the audible frequency range on two different kinds of rubber: silicone and natural rubber with a respective iron particle volume concentration of 33%. The particles used are of irregular shape and randomly distributed within the rubber. An external magnetic field of 0-0.8 T is applied. Both kinds of rubber are found to be strongly amplitude dependent and, furthermore, displaying large responses to externally applied magnetic fields - a maximum of 115%. Also included are graphs of measurements on silicone and natural rubber devoid of iron particles. Those results support the conclusion that introducing iron particles in the rubber gives rise to a strong, non-negligible, amplitude dependence in the entire frequency range.

  • 308.
    Blom, Peter
    et al.
    KTH, Tidigare Institutioner, Farkostteknik.
    Kari, Leif
    KTH, Tidigare Institutioner, Farkostteknik.
    Magneto-rheological rubber isolators in the audible frequency range2004Inngår i: Nordic Vibration Research, 2004Konferansepaper (Annet vitenskapelig)
  • 309.
    Blom, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Magneto-sensitive rubber in the audible frequency range2005Inngår i: CONSTITUTIVE MODELS FOR RUBBER IV / [ed] Per-Erik Austrell, Leif Kari, London: Taylor & Francis, 2005Konferansepaper (Fagfellevurdert)
  • 310.
    Blom, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Smart audio frequency energy flow control by magneto-sensitive rubber isolators2008Inngår i: Smart materials and structures (Print), ISSN 0964-1726, E-ISSN 1361-665X, Vol. 17, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A magneto-sensitive rubber isolator inserted between a source and an infinite plate is modelled in the audible frequency range, and the energy flow into the plate with the rubber subjected to a magnetic field applied perpendicular to the axial displacement is calculated. Subsequently the result is compared to the corresponding energy flow for zero magnetic induction; upon the application of an external magnetic field the rubber becomes stiffer, thus shifting the internal resonances of the isolator. This is a fast and reversible process enabling adaption of the isolator to rapidly changing audio frequency conditions by simply turning on and off a magnetic field. In the application example considered, the energy flow into the plate at the first internal dynamic peak stiffness frequency is reduced by approximately 7 dB-a large difference in a sound and vibration context-by inducing magnetic saturation of the rubber.

  • 311.
    Blom, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    The frequency, amplitude and magnetic field dependent torsional stiffness of a magneto-sensitive rubber bushing2011Inngår i: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 60, nr 1, s. 54-58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dynamic torsional stiffness model of a magneto-sensitive circular annular rubber bushing is presented where influences of frequency, amplitude and magnetic field dependence are included. This is achieved by employing a newly developed non-linear magneto-sensitive audio frequency constitutive equation in an engineering formula for the torsional stiffness of a rubber bushing. The engineering stiffness formula predicts the frequency and amplitude dependent stiffness in a simple way, based on geometric dimensions and the shear modulus. The shear modulus is provided by the rubber model. The results from these calculations predict and clearly display the possibility of controlling over a large frequency range, through the application of a magnetic field, the magneto-sensitive rubber bushing stiffness.

  • 312.
    Blomberg, C
    KTH.
    Aspects of fluctuations in non-linear biological systems - Motion in bistable potentials and selection equations2004Inngår i: SIMPLICITY BEHIND COMPLEXITY / [ed] Klonowski, W, LENGERICH: PABST SCIENCE PUBLISHERS , 2004, Vol. 3, s. 25-60Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Two rather different topics are discussed with one common factor: they are driven by irregular influences. The first part considers the stochastic transition between potential minima over a maximum (barrier), and is treated as a Brownian motion description of reaction rates. We also discuss the related problem of "stochastic resonance", in which a small oscillating force synchronises transitions. In both these cases, the emphasis is on the formalism, and the relations between the two problems are stressed. The other type of problem considers growth and competition equations of macromolecules, relevant for early molecular evolution on the path to the first life. Selection rates are simple and straightforward as long as competition essentially concerns limited resources. The situation gets more complex, when molecules are considered co-operative, e.g. they can catalyse growth processes. This corresponds to the hypercycle concept of Eigen, and is also a scenario for a RNA world. Components that use the support from other components may thrive, but can lead to the extermination of an entire system as the supporters may decline in the competition. As in the first part, the emphasis is on the formalism. We also take up probability aspects and problems that appear together with small probabilities and possibilities of exponential growth. Finally, the possibility of saving the co-operativity by spatial structures are discussed.

  • 313.
    Blomfors, Mattias
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB, Betong & Berg.
    Zandi, Kamyab
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB, Betong & Berg.
    Lundgren, Karin
    Larsson, Oskar
    Honfi, Dániel
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Engineering Assessment Method for Anchorage in Corroded Reinforced Concrete2016Inngår i: IABSE Congress Stockholm, 2016: Challenges in Design and Construction of an Innovative and Sustainable Built Environment. Report, IABSE c/o ETH Hönggerberg , 2016, s. 2109-2116Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There is an increasing need for reliable methods to assess load-carrying capacity and remaining service life of existing infrastructure. Several previous research projects have resulted in a verified, simple 1D model for assessment of anchorage in corroded reinforced concrete structures. Previous verification has involved both experiments and detailed 3D NLFE analyses. To further develop the 1D model it needs to be extended to comprise more practical situations. In order to facilitate an efficient extension procedure in the future, the size of 3D NLFE model that is required to capture the bond behaviour between corroded reinforcement and concrete is investigated. Beam-end models and models of sub-sections were studied, and the results in terms of bond stress and crack pattern were compared. Preliminary results indicate good agreement for some situations; however for some cases a section model seems to overestimate the capacity.

  • 314.
    Bodin, Olle
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Simulations of compressible flows associatedwith internal combustion engines2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Vehicles with internal combustion (IC) engines fueled by hydrocarbon compoundshave been used for more than 100 years for ground transportation.During these years and in particular the last decade, the environmental aspectsof IC engines have become a major political and research topic. Followingthis interest, the emissions of pollutants such as NOx, CO2 and unburnedhydrocarbons (UHC) from IC engines have been reduced considerably.Yet, there is still a clear need and possibility to improve engine efficiencywhile further reducing emissions of pollutants. The maximum efficiency ofIC engines used in passenger cars is no more than 40% and considerably lessthan that under part load conditions. One way to improve engine efficiencyis to utilize the energy of the exhaust gases to turbocharge the engine. Whileturbocharging is by no means a new concept, its design and integration intothe gas exchange system has been of low priority in the power train designprocess. One expects that the rapidly increasing interest in efficient passengercar engines would mean that the use of turbo technology will become morewidespread.The flow in the IC-engine intake manifold determines the flow in the cylinderprior and during the combustion. Similarly, the flow in the exhaust manifolddetermines the flow into the turbine, and thereby the efficiency of theturbocharging system.In order to reduce NOx emissions, exhaust gas recirculation (EGR) is used.As this process transport exhaust gases into the cylinder, its efficiency is dependenton the gas exchange system in general. The losses in the gas exchangesystem are also an issue related to engine efficiency. These aspects have beenaddressed up to now rather superficially. One has been interested in globalaspects (e.g. pressure drop, turbine efficiency) under steady state conditions.In this thesis, the flow in the exhaust port and close to the valve as wellas in the exhaust manifold is studied. Since the flow in the port can be transonic,we study first the numerical modeling of such a flow in a more simplegeometry, namely a bump placed in a wind tunnel. Large-Eddy Simulationsof internal transonic flow have been carried out. The results show that transonicflow in general is very sensitive to small disturbances in the boundaryconditions. Flow in the wind tunnel case is always highly unsteady in the transonicflow regime with self excited shock oscillations and associated with that 

    also unsteady boundary-layer separation. The interaction between separationzone and shock dynamics was carried out by one-, and two-point correlationsas well as dynamic mode decomposition (DMD). A clear connection betweenseparation bubble dynamics and shock oscillation was found. To investigatesensitivity to periodic disturbances the outlet pressure in the wind tunnel casewas varied periodically at rather low amplitude. These low amplitude oscillationscaused hysteretic behavior in the mean shock position and appearance ofshocks of widely different patterns.The study of a model exhaust port shows that at realistic pressure ratios,the flow is transonic in the exhaust port. Furthermore, two pairs of vortexstructures are created downstream of the valve plate by the wake behind thevalve stem and by inertial forces and the pressure gradient in the port. Thesestructures dissipate rather quickly. The impact of these structures and thechoking effect caused by the shock on realistic IC engine performance remainsto be studied in the future.The flow in a heavy-duty exhaust manifold was studied under steady andengine-like boundary conditions. At all conditions, significantly unsteady flowis generated in the manifold and at the inlets to the turbine and EGR cooler.The inflow to the turbine is dominated by a combination of the blow-downpulse coming from one cylinder, and the scavenging pulse from another at thefiring frequency.

  • 315. Boer, C.R.
    et al.
    Gudmundson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Rebelo, N
    Comparison of elasto-plastic FEM, rigid-plastic FEM and experiments for cylinder upsetting1982Konferansepaper (Fagfellevurdert)
  • 316.
    Boere, S.W.
    et al.
    Department of Mechanical Engineering, Eindhoven University of Technology.
    Lopez Arteaga, Ines
    Department of Mechanical Engineering, Eindhoven University of Technology.
    Kuijpers, A.H.W.M.
    Department of Mechanical Engineering, Eindhoven University of Technology.
    Nijmeijer, H.
    Department of Mechanical Engineering, Eindhoven University of Technology.
    Prediction of road texture influence on rolling resistance and tire/road noise2009Inngår i: Proceedings of Euronoise 2009, 2009Konferansepaper (Annet vitenskapelig)
  • 317. Bogey, Christophe
    et al.
    Gojon, Romain
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Feedback loop and upwind-propagating waves in ideally expanded supersonic impinging round jets2017Inngår i: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 823, s. 562-591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aeroacoustic feedback loop establishing in a supersonic round jet impinging on a flat plate normally has been investigated by combining compressible large-eddy simulations and modelling of that loop. At the exit of a straight pipe nozzle of radius r(0), the jet is ideally expanded, and has a Mach number of 1.5 and a Reynolds number of 6 x 10(4). Four distances between the nozzle exit and the flat plate, equal to 6r(0), 8r(0), 10r(0) and 12r(0), have been considered. In this way, the variations of the convection velocity of the shear-layer turbulent structures according to the nozzle-to-plate distance are shown. In the spectra obtained inside and outside of the flow near the nozzle, several tones emerge at Strouhal numbers in agreement with measurements in the literature. At these frequencies, by applying Fourier decomposition to the pressure fields, hydrodynamic-acoustic standing waves containing a whole number of cells between the nozzle and the plate and axisymmetric or helical jet oscillations are found. The tone frequencies and the mode numbers inferred from the standing-wave patterns are in line with the classical feedback-loop model, in which the loop is closed by acoustic waves outside the jet. The axisymmetric or helical nature of the jet oscillations at the tone frequencies is also consistent with a wave analysis using a jet vortex-sheet model, providing the allowable frequency ranges for the upstream-propagating acoustic wave modes of the jet. In particular, the tones are located on the part of the dispersion relations of the modes where these waves have phase and group velocities close to the ambient speed of sound. Based on the observation of the pressure fields and on frequency-wavenumber spectra on the jet axis and in the shear layers, such waves are identified inside the present jets, for the first time to the best of our knowledge, for a supersonic jet flow. This study thus suggests that the feedback loop in ideally expanded impinging jets is completed by these waves.

  • 318. Bolinder, T.
    et al.
    Faleskog, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Evaluation of the influence of residual stresses on ductile fracture2015Inngår i: Journal of Pressure Vessel Technology-Transactions of the ASME, ISSN 0094-9930, E-ISSN 1528-8978, Vol. 137, nr 6, artikkel-id 061408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, the significance of residual stresses on ductile fracture is investigated by a set of experiments that are analyzed by finite element simulations. The treatment of residual stresses as expressed in fracture assessment procedures such as R6 is believed to be very conservative for ductile materials, when fracture occurs at high primary loads. Earlier numerical studies have reinforced this belief. This is supported in the current study. Tests on notched 3PB specimens with and without residual stresses were conducted on two ferritic steels. The residual stresses were introduced by applying a compressive preload on notched specimens. The tests were designed to achieve crack initiation at load levels around the plastic limit load. The crack growth in the tests was measured by a compliance method and by color marking of the crack surface. The crack tip driving force J was evaluated numerically for specimens with and without residual stresses. The experimental results show that the residual stresses clearly contribute to J at low primary loads. However, this contribution diminishes as the primary loads increase. The experimental results were also compared with results evaluated using the R6 procedure. These comparisons revealed overly high conservatism in R6 for cases with residual stresses compared to the ones for cases without residual stresses where less conservatism was evident.

  • 319. Bolinder, T.
    et al.
    Sattari-Far, I.
    Faleskog, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Evaluation of the influence of residual stresses on ductile fracture2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work the significance of residual stresses for ductile fracture was investigated. The treatment of residual stresses as expressed in fracture assessment procedures such as the R6 method is believed to be very conservative for ductile materials, when fracture occurs at high primary loads. Earlier numerical studies have reinforced this belief. Tests on notched 3PB specimens with and without residual stresses were conducted on two ferritic steels. The residual stresses were introduced by applying a compressive pre-load on notched specimens. The tests were designed to achieve crack initiation at load levels around the limit load. The crack growth in the tests was measured by a compliance method and by colour marking of the crack surface. The crack-tip driving force J was evaluated numerically for specimens with and without residual stresses. The experimental results show that the residual stresses clearly contribute to J at low primary loads. However, this contribution diminishes as the primary loads increase. The experimental results were also compared with results evaluated using the R6 procedure. These comparisons revealed an overly high conservativeness in R6 for cases with residual stresses compared to the conservativeness for cases without residual stresses.

  • 320.
    Boqvist, Emil
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska högskolan.
    Investigation of a swing check valve using CFD2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master’s thesis is made to increase the understanding of the dynamic characteristics of a typical large swing check valve used in a system that transports pressurized water to a reactor tank.3D FSI-simulations are performed for a number of transients in order to study the dynamic characteristics their dependence of the deceleration rate. The purpose is to find information about the dynamics that could be used in a future improvement of a 1D-model.Steady state simulations are performed for angles in the whole spectrum. Seven transient FSI-simulations with different constantly decelerating flows from 630 kg/s2 (6.7 m/s2) to 40 320 kg/s2 (430 m/s2) have been performed. The pressure on the disc caused by the hydraulic torque is integrated and the corresponding torque contribution, together with the weight torque, is used in the second law of motion to calculate the movement of the disc throughout the transients.Steady state simulations yield the pressure drop over the valve, which could be compared with field measurements in order to validate the CFD-simulations. Comparison of the pressure distribution on the disc for the steady state and transient simulations shows the importance of taking the disc angular velocity into account when modelling in 1D. Correlations between the angle, angular velocity, torque and mass flow are obtained from the transient FSI-simulations. Torque coefficients according to (Li & Liou, Vol. 125) are also brought out from the simulated transients, but in order to create a model in line with this approach further simulations have to be performed. A prediction of the pressure rise that occurs when a swing check valve closes in backward flow according to the Joukowsky equation is brought out and gives an idea of the loadings that the system has to be able to handle.

  • 321. Borg, K I
    et al.
    Soderholm, Lars
    KTH, Tidigare Institutioner, Mekanik.
    Essen, Hanno
    KTH, Tidigare Institutioner, Mekanik.
    Response to "Comment on 'Force on a spinning sphere moving in a rarefied gas' and 'On the inverse Magnus effect in free molecular flow'" [Phys. Fluids 16, 3832 (2004)]2004Inngår i: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 16, nr 10, s. 3833-3833Artikkel i tidsskrift (Annet vitenskapelig)
  • 322.
    Borhani Khomami, Arghavan
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Separate analysis of Small Pipes in Piping Analysis.2015Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A piping system generally consists of primary system, large pipes, and secondary system, small pipes [1]. The primary system can be analysed separately without considering the secondary system. However, the opposite is not true because the primary system affects the movement of the secondary system. The aim of this study is to investigate the possibility of analysing the small pipes separately, which is called for sub-modelling, and then if the sub-modelling is possible, generate and validate a method which makes this sub-modelling possible.

    The response spectrum method [2] is used for analysing the structure. A ground acceleration spectra in three directions is applied at the primary structure, a new floor response spectra is then generated with the results from the analysis of the primary structure [3]. The calculated floor response spectra is applied at the secondary structure. The results from this analysis is compared to the results from applying the ground acceleration at the total structure. Two different ground accelerations are applied on two different models. A separation would be allowed if the results of the secondary structure are more than 90% of the results of the whole structure in all parts of the secondary structure in all studied cases. The results after separation reach more than 100% of the results from the analysis of the whole structure, called for conservative results, in three cases but not all the cases. The separation will be allowed in those three cases where the results reach 90% of the results taken from the whole structure, but not in that case where results does not reach 90%.

  • 323.
    Borodulina, Svetlana
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Kulachenko, Artem
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Tjahjanto, Denny
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Constitutive modeling of a paper fiber in cyclic loading applications2015Inngår i: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 110, s. 227-240Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The tensile response of dense fiber-based materials like paper or paperboard is mainly dependent of the properties of the fibers, which store most of the elastic energy. In this paper, we investigate the influence of geometrical and material parameters on the mechanical response of the pulp fibers used in paper manufacturing. We developed a three-dimensional finite element model of the fiber, which accounts for microfibril orientation of cellulose fibril, and the presence of lignin in the secondary cell wall. The results showed that the change in the microfibril orientation upon axial straining is mainly a geometrical effect, and is independent of the material properties of the fiber, as long as the deformations are elastic. Plastic strain accelerates the change in microfibril orientation and thus makes it material-dependent. The results also showed that the elastic modulus of the fiber has a non-linear dependency on microfibril angle, with elastic modulus being more sensitive to the change of microfibril angle around small initial values of microfibril angles. Based on numerical results acquired from a 3D fiber model supported by available experimental evidence, we propose an anisotropic-kinematic hardening plasticity model for a fiber within a beam framework. The proposed fiber model is capable of reproducing the main features of the cyclic tensile response of a pulp fiber, such as stiffening due to changing microfibril angle. The constitutive model of the fiber was implemented in a finite-element model of the fiber network. By using the fiber network model, we estimated the level of strain that fiber segments accumulate before the typical failure strain of the entire network is reached.

  • 324.
    Boåsen, Magnus
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Pressure pulsations in common rail fuel systems as a mechanical loading on fuel pipes.2015Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Modern fuel systems (Common Rail/XPI) on diesel engines store the fuel under a high pressure right before injection into the combustion chamber. Fuel pipes in common rail systems have been observed to be excited to resonance during running conditions of the engine (pressure pulsations as exciting mechanism). This thesis have had the focus on characterizing and modeling the loading of these pipes in form of pressure pulsations in the stored fuel as a prerequisite for future simulations. The thesis have included a part of measurements using strain gauges directly applied to the boundary of the pipes, analytical modeling of the pressure pulsations and a concluding comparison/validation part where the measurements and the model results are compared.

  • 325.
    Brandberg, August
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    The Effect of Geometry on the Mechanical Properties of Paper Fiber Bonds2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 326. Brandt, Anders
    A Digital Filter Method for Forced Response Computation2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Transient forced response of mechanical structures is usually computed using time domain integration. This is often computationally costly, and the numerical precision and stability are concerns. In the present paper, a novel method based on modal superposition, using a new digital filter implementation, is presented. Poles and residues of the model are used as input data, which allows for using data from a finite element model, a lumped parameter model, or from experimental modal analysis. Modal damping can be used if the damping matrix is unknown. With the proposed method, the frequency dependant error can easily be computed, and can be chosen arbitrarily small by selecting proper sampling frequency (time increment). The method is applicable to all linear structures and can be used for stationary or transient input data. Simulation results show that the new method is superior to the alternative methods, at less computational cost.

  • 327. Brandt, Anders
    et al.
    Ahlin, Kjell
    Sampling and Time-Domain Analysis2010Inngår i: Sound and Vibration, ISSN 0022-460X , Vol. 44, nr 5, s. 13-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Most noise and vibration measurement and analysis systems are able to record time history signals for subsequent processing. This article deals with some important aspects of recording and processing these data streams in order to maintain analysis integrity.

  • 328. Brandt, Anders
    et al.
    Ahlin, Kjell
    Lagö, Thomas L
    Noise and vibration measurement system basics2006Inngår i: SOUND AND VIBRATION, ISSN 0022-460X , Vol. 40, nr 4, s. 9-11Artikkel i tidsskrift (Fagfellevurdert)
  • 329. Brandt, Anders
    et al.
    Lagö, Thomas L
    Ahlin, Kjell
    Tuma, Jiri
    Main principles and limitations of current order tracking methods2005Inngår i: SOUND AND VIBRATION, ISSN 0022-460X , s. 19-22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Order tracking is a widely used tool for analysis of vibrations generated in vehicle drivetrain components, since many vibrations are related to engine RPMs. In recent years, offline order tracking has become suitable due to enhanced computer speeds. Many methods, some patented, for both online and offline order tracking have been presented over the years. This article reviews some basic ideas behind current methods and compares their main advantages and limitations. Some basic time-frequency concepts and time window effects are reviewed. Questions on suitable tachometers and their number of pulses per revolution are also addressed. The possibility of processing RPM dependent data without tachometers is also discussed.

  • 330.
    Brandt, Anders
    et al.
    University of Southern Denmark, Denmark.
    Linderholt, Andreas
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    A Periodogram-Based Method for Removing Harmonics in Operational Modal Analysis2012Inngår i: International Conference on Noise and Vibration Engineering 2012 (ISMA 2012): Proceedings of a meeting held 17-19 September 2012, Leuven, Belgium. Including USD 2012 / [ed] P. Sas, S. Jonckheere & D. Moens, Leuven: Katholieke Universiteit Leuven, Department of Mechanical Engineering , 2012, s. 2625-2634Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In many cases where operational modal analysis is of interest, harmonic components are disturbing the estimation of modal parameters. Sometimes the harmonics can be included in the parameter estimation process and subsequently removed (because the damping values become unrealistically low). However, this is difficult if a natural frequency is very close to, or coincides with, a harmonic. In this paper we investigate a recently proposed method for removing harmonics when estimating spectral densities for operational modal analysis. The method is essentially based on removing the harmonics in a periodogram, prior to estimating the spectral density by smoothing the same periodogram. This makes it a very time efficient method, as the harmonic removal is integrated into the spectral analysis process. To produce data for testing the method, a finite element dynamic model representing a wind turbine was created. The MATLAB-based finite element code CALFEM was used to achieve a flexible description of the tower. An aerodynamic force representation excited the rotating structure. An unbalance in one of the blades was introduced to produce a harmonic at the rotation speed of the turbine. To validate the efficiency of the harmonic removal, modal parameters were estimated using simulated data prior to, and after, removing the harmonics. The results show that the harmonic removal with the proposed method is efficient.

  • 331.
    Brandt, Luca
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Cossu, C
    Henningson, Dan S
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Chomaz, J M
    Huerre, P
    Numerical studies of streak instability in boundary layers2006Inngår i: Sixth IUTAM Symposium on Laminar-Turbulent Transition / [ed] Govindarajan, R, DORDRECHT: SPRINGER , 2006, Vol. 78, s. 121-126Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Numerical results on the stability of boundary layers in the presence of streaks, assumed steady and spanwise periodic, are presented. The instability features are retrieved both from stability analysis and from the numerical simulation of the flow impulse response. It is found that the presence of streaks of moderate amplitudes is able to quench the viscous Tollmien-Schlichting waves. However, a threshold exists beyond which secondary inflectional instabilities occur. Streaky basic flows unstable to both sinuous and varicose perturbations are considered. To gain physical understanding of the instability mechanisms the equation for the perturbation kinetic energy is analysed. To investigate the sinuous instability modes an analytical model streak is also proposed.

  • 332.
    Brandt, Luca
    et al.
    KTH, Tidigare Institutioner, Mekanik.
    Henningson, Dan S.
    KTH, Tidigare Institutioner, Mekanik.
    Direct numerical simulations of streak breakdown in boundary layers2004Inngår i: Direct and Large-Eddy Simulation V, Proceedings / [ed] Friedrich, R; Geurts, BJ; Metais, O, 2004, Vol. 9, s. 175-196Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Numerical simulations of bypass transition in Blasius boundary layers are presented. The breakdown of streamwise streaks is first considered in the case of the steady, spanwise periodic basic flows arising from the nonlinear saturation of optimal perturbations and then in the case of transition in boundary layers subject to free-stream turbulence. Similarity and differences with previous work are discussed.

  • 333.
    Brauer, Jesper
    KTH, Tidigare Institutioner, Maskinkonstruktion.
    A general finite element model of involute gears2004Inngår i: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 40, nr 13-14, s. 1857-1872Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Involute gears comprise primarily spur gears, helical gears, straight conical involute gears and conical involute gears. Robust and effective parameterised finite element models of involute gears should be based on analytically derived mathematical representations of their shape. In this paper we derive a mathematical description of conical involute gears that is also capable of representing three other types of involute gear. The equations and the intervals for the surface parameters are then used to create a general finite element model of involute gears.

  • 334.
    Brethouwer, Gert
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Matsuo, Y.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    DNS of rotating homogeneous shear flow and scalar mixing2006Inngår i: Direct and Large-Eddy Simulation VI / [ed] Lamballais, E; Friedrich, R; Geurts, BJ; Metais, O, DORDRECHT: SPRINGER , 2006, Vol. 10, s. 225-232Konferansepaper (Fagfellevurdert)
  • 335.
    Broberg, Patrik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Imaging and analysis methods for automated weld inspection2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    All welding processes can give rise to defects, which weakens the joint and can eventually lead to the failure of the welded structure. In order to inspect welds for detects, without affecting the usability of the product, non-destructive testing (NDT) is needed. NDT includes a wide range of different techniques, based on different physical principles, each with its advantages and disadvantages. The testing is often performed manually by a skilled operator and in many cases only as spot-checks. Today the trend in industry is to move towards thinner material, in order to save weight for cost and for environmental reasons. The need for inspection of a larger portion of welds therefore increases and there is an increasing demand for fully automated inspection, including both the mechanised testing and the automatic analysis of the result. Compared to manual inspection, an automated solution has advantages when it comes to speed, cost and reliability. A comparison of several NDT methods was therefore first performed in order to determine which methods have most potential for automated weld inspection. Automated analysis of NDT data poses several difficulties compared to manual data evaluation. It is often possible for an operator to detect defects even in noisy data, through experience and knowledge about the part being tested. Automatic analysis algorithms on the other hand suffer greatly from both random noise as well as indications that originate from geometrical variations. The solution to this problem is not always obvious. Some NDT techniques might not be suitable for automated inspection and will have to be replaced by other, better adapted methods. One such method that has been developed during this work is thermography for the detection of surface cracks. This technique offers several advantages, in terms of automation, compared to existing methods. Some techniques on the other hand cannot be easily replaced. Here the focus is instead to prepare the data for automated analysis, using various pre-processing algorithms, in order to reduce noise and remove indications from sources other than defects. One such method is ultrasonic testing, which has a good ability for detecting internal defects but suffers from noisy signals with low spatial resolution. Work was here done in order to separate indications from corners from other indications. This can also help to improve positioning of the data and thereby classification of defects. The problem of low resolution was handled by using a deconvolution algorithm in order to reduce the effect of the spread of the beam.The next step in an automated analysis system is to go beyond just detection and start characterising defects. Using knowledge of the physical principles behind the NDT method in question and how the properties of a defect affect the measurement, it is sometimes possible to develop methods for determining properties such as the size and shape of a defect. This kind of characterisation of a defect is often difficult to do in the raw data, and is therefore an area where automated analysis can go beyond what is possible for an operator during manual inspection. This was shown for flash thermography, where an analysis method was developed that could determine the size, shape and depth of a defect. Similarly for laser ultrasound, a method was developed for determining the size of a defect.

  • 336.
    Broberg, Patrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för process- och produktutveckling.
    Towards Automation of Non-Destructive Testing of Welds2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    All welding processes can give rise to defects that will weaken the joint and can lead to failure of the welded structure. Because of this, non-destructive testing (NDT) of welds have become increasingly important to ensure the structural integrity when the material becomes thinner and stronger and welds become smaller; all to reduce weight in order to save material and reduce emissions due to lighter constructions.

    Several NDT methods exists for testing welds and they all have their advantages and disadvantages when it comes to the types and sizes of defects that are detectable, but also in the ability to automate the method. Several methods were compared using common weld defects to determine which method or methods were best suited for automated NDT of welds. The methods compared were radiography, phased array ultrasound, eddy current, thermography and shearography. Phased array ultrasound was deemed most suitable for detecting the weld defects used in the comparison and for automation and was therefore chosen to be used in the continuation of this work. Thermography was shown to be useful for detecting surface defects; something not easily detected using ultrasound. A combination of these techniques will be able to find most weld defects of interest.

    Automation of NDT can be split into two separate areas; mechanisation of the testing and automation of the analysis, both presenting their own difficulties. The problem of mechanising the testing has been solved for simple geometries but for more general welds it will require a more advance system using an industrial robot or similar. Automation of the analysis of phased array ultrasound data consists of detection, sizing, positioning and classification of defects. There are several problems to solve before a completely automatic analysis can be made, including positioning of the data, improving signal quality, segmenting the images and classifying the defects. As a step on the way towards positioning of the data, and thereby easing the analysis, the phase of the signal was studied. It was shown that the phase can be used for finding corners in the image and will also improve the ability to position the corner as compared to using the amplitude of the signal. Further work will have to be done to improve the signal in order to reliably analyse the data automatically.

  • 337.
    Broberg, Patrik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Towards automation of non-destructive testing of welds2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    All welding processes can give rise to defects that will weaken the joint and can lead to failure of the welded structure. Because of this, non-destructive testing (NDT) of welds have become increasingly important to ensure the structural integrity when the material becomes thinner and stronger and welds become smaller; all to reduce weight in order to save material and reduce emissions due to lighter constructions.Several NDT methods exists for testing welds and they all have their advantages and disadvantages when it comes to the types and sizes of defects that are detectable, but also in the ability to automate the method. Several methods were compared using common weld defects to determine which method or methods were best suited for automated NDT of welds. The methods compared were radiography, phased array ultrasound, eddy current, thermography and shearography. Phased array ultrasound was deemed most suitable for detecting the weld defects used in the comparison and for automation and was therefore chosen to be used in the continuation of this work. Thermography was shown to be useful for detecting surface defects; something not easily detected using ultrasound. A combination of these techniques will be able to find most weld defects of interest. Automation of NDT can be split into two separate areas; mechanisation of the testing and automation of the analysis, both presenting their own difficulties. The problem of mechanising the testing has been solved for simple geometries but for more general welds it will require a more advance system using an industrial robot or similar. Automation of the analysis of phased array ultrasound data consists of detection, sizing, positioning and classification of defects. There are several problems to solve before a completely automatic analysis can be made, including positioning of the data, improving signal quality, segmenting the images and classifying the defects. As a step on the way towards positioning of the data, and thereby easing the analysis, the phase of the signal was studied. It was shown that the phase can be used for finding corners in the image and will also improve the ability to position the corner as compared to using the amplitude of the signal. Further work will have to be done to improve the signal in order to reliably analyse the data automatically.

  • 338. Broman, Göran
    Computational Engineering2003Bok (Annet vitenskapelig)
    Abstract [en]

    This book is the main course literature in the course Computational Engineering, which comprises 22,5 ECTS (European Credit Transfer System), within the programme of Master of Science in Mechanical Engineering with emphasis on Structural Mechanics at Blekinge Institute of Technology. The book starts with rather simple numerical methods for ordinary differential equations and ends with advanced topics such as finite element procedures for systems of transient, non-linear and coupled partial differential equations. Several topics from physics and engineering are included to support the study of the numerical methods.

  • 339. Broman, Göran
    Implications of cavitation in individual grooves of spiral groove bearings2001Inngår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 215, nr J5, s. 417-424Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pressure distribution in a flat spiral groove thrust bearing obtained from a straightforward solution of the Reynolds equation includes subatmospheric pressure in part of the grooved area, This is masked in the common theory based on the assumption of an infinite number of grooves. Furthermore, the negative contribution to the load capacity from this area is usually small, which may explain why the presence of subatmospheric pressure has not been given much attention in connection with these bearings. Subatmospheric pressure is, however, necessary for liquid-lubricated flat spiral groove thrust bearings of conventional design to work at all at low numbers of grooves, which in turn requires a non-zero cavitation pressure. Cavitation within individual grooves implies non-linearity in, for example, the relation between load capacity and rotational speed of the bearing and limits the obtainable load capacity. This is more pronounced and important to consider at low numbers of grooves (wide grooves) than at high numbers of grooves (narrow grooves), and it is difficult to determine for what number of grooves that reliable prediction of bearing performance can be expected. It depends on the actual value of the cavitation pressure and other parameters that are usually unknown or difficult to account for. To avoid this disadvantage a modified design of liquid-lubricated flat spiral groove thrust bearings is suggested.

  • 340.
    Broman, Göran
    Blekinge Tekniska Högskola, Institutionen för maskinteknik.
    Miljöinslag i grundutbildningen vid Högskolan i Karlskrona/Ronneby1997Annet (Annet vitenskapelig)
    Abstract [sv]

    Högskolan i Karlskrona/Ronneby grundades 1989, och är därmed en av Sveriges yngsta högskolor. Grundutbildning bedrivs inom ämnesområdena teknik, datavetenskap, arbetsvetenskap, ekonomi, språk och kultur. Antalet anställda är ca 220 och antalet studenter ca 2500. Utvecklingstakten är hög och fortfarande kännetecknas ledning och personal av pionjäranda och öppenhet för initiativ, vilket varit till glädje också för detta projekt. Tillämpad informationsteknologi ges hög prioritet och finns som ett naturligt inslag i hela högskolans verksamhet. En målsättning är att också integrera miljöaspekter. Genom anslag från Högskolans Grundutbildningsråd till detta projekt påbörjades 1994 miljöintegrering inom 120p-programmet i maskinteknik med inriktning mot utvecklingsteknik, vid Institutionen för Maskinteknik (IMA), och 180p-programmet i fysisk planering, vid Institutionen för Fysisk Planering och Byggteknik (IFB). Biblioteket deltog också från början för att ge stöd åt projektledning och lärare vid deras integreringsarb ete, samt för att miljöintegrera sin egen verksamhet som stöd för personal och studenter även fortsättningsvis. Ett delmål med projektet var att ge deltagande lärare och övrig personal sådana kunskaper om bärkraftig utveckling - och nödvändigheten därav - att de skulle känna engagemang och själva se möjligheterna till miljöinslag i sina respektive ämnen och övriga yrkesuppgifter. Stor vikt lades därför på personalutbildning, som genomfördes i form av en seminarieserie samt genom handledda fortsatta självstudier och deltagande i externa kurser, konferenser och studiebesök. Resultatet blev gott. Nästan alla lärare vid IMA och IFB fick ett ökat engagemang och deltog aktivt i miljöintegreringsarbetet. Engagemanget har också borgat för fortsatt lärande och automatiska kursförbättringar efter projektets slut, vilket var tanken. Synliga resultat är en vidareutvecklad miljögrundkurs, Miljögrunder 5p, obligatorisk i programmet maskinteknik med inriktning mot utvecklingsteknik och tillgänglig även för andra studenter s om fristående kurs, samt nya kursplaner i de ämnen miljöintegrering bedömts mest relevant i de båda programmen. Även i examination, projektrapporter och examensarbeten syns naturligtvis resultat av miljöintegreringen. Totalt har ca hälften av kurserna inom respektive utbildningsprogram direkt berörts av projektet. Genom följdeffekter har i någon mån även övriga delar av programmen påverkats. Studenterna framför vid kurs-utvärderingar och andra diskussioner att de upplever miljöintegreringen som mycket positiv för deras utbildning och ser den som en värdefull merit då de söker jobb. Miljöinslag har kunnat införas utan att de reguljära ämnena tagit skada - alltså i motsägelse till diskussionen om att värdefulla befintliga kunskaper måste trängas undan när någon "nymodighet" ska föras in i en utbildning. Miljöintegreringen har snarare gjort att studenternas motivation för de reguljära ämnena ökat. Denna tulipanaros har kunnat åstadkommas huvudsakligen genom att: - använda grundläggande kunskaper som reguljärt ingår i utbildningsprogrammen, t ex viss naturvetenskap, för att bygga upp en systemsyn genom vilken miljö- och resursproblemens orsaker och lösningar på principiell nivå blir tydliga. - använda denna systemsyn som ett ramverk i vilket detaljkunskaper som reguljärt ingår i utbildningsprogrammen kan inordnas och ges en övergripande mening, varigenom också sambanden mellan olika ämnen blir tydligare. - exemplifiera de reguljära ämneskunskaperna på ett delvis nytt sätt och visa på alternativa tillämpningar för att stimulera studenternas kreativitet beträffande hur deras yrkeskunskaper konkret kan användas för att lösa miljö- och resursproblemen. Den bärande idén med miljöintegreringen har just varit att med ovanstående som förutsättning, så är det främst genom att bli duktiga i klassiska ämnen för ingenjörer och fysiska planerare som ingenjörer och fysiska planerare kan göra den största insatsen för en bärkraftig utveckling. Att göra om dem till "miljöexperter" i traditionell mening vore inte fruktbart. Det Naturliga Stegets definition av bärkraftighet och modell för planering av bärkraftig utveckling, som visat sig så framgångsrik inom näringslivet, har visat sig lämplig även inom den högre utbildningen. Den har utgjort grunden för den systemsyn som använts i detta projekt enligt ovan. Projektet har troligen även bidragit som inspirationskälla, åtminstone som en av flera faktorer, till verksamheter utanför dess ram. Exakt hur mycket är naturligtvis svårt att bedöma. Ökade kunskaper och det allmänt ökade intresset för miljöfrågor har i varje fall lett till allt ifrån konkreta saker som införskaffande av institutionscykel för kortare ärenden och vindkraftverk och solpaneler som komplement till energiundervisningen, till deltagande i internationella miljöutbildningsprojekt, doktorandverksamhet i miljöanpassad produktutveckling, inrättandet av professurer med miljöprofil, och ansvar för högskolans miljöpolicy och miljöplan. Detta utgör naturligtvis omvänt också ett starkt stöd för underhåll och utveckling av miljöintegreringen. Den bedöms därför ha utmärkta förutsättningar att bli bestående vid IMA och IFB och förhoppningsvis sprida sig till övriga institutioner och utbildningsprogram.

  • 341. Broman, Göran
    et al.
    Hermann, Madeleine
    Jönsson, Anders
    Modelling Bellows Expansion Joints by Standard Beam Finite Elements2000Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A procedure for modelling bellows expansion joints by the standard beam finite elements of I-DEAS Master Series 6 is presented. It is shown that the bellows dynamic behaviour can be modelled by beam elements by manipulating certain element parameters. The method will work in any software in which these parameters can be set by the user. Compared to a shell elements model the model size is reduced by at least a factor of 100. This is especially advantageous when the bellows is only a part of a system to be optimised with respect to overall design parameters. In comparison to existing "semi-analytical" methods the beam finite elements have the advantages of considering axial, bending and torsion degrees of freedom simultaneously and that the interaction between the bellows and the rest of the system, also modelled by beam or shell finite elements, is easily facilitated. The procedure is verified by experimental results from other investigators.

  • 342.
    Broman, Göran
    et al.
    Blekinge Tekniska Högskola, Institutionen för maskinteknik.
    Hermann, Madeleine
    Blekinge Tekniska Högskola, Institutionen för maskinteknik.
    Jönsson, Anders
    Blekinge Tekniska Högskola, Institutionen för maskinteknik.
    Modelling Flexible Bellows by Standard Beam Finite Elements1999Rapport (Annet vitenskapelig)
    Abstract [en]

    A procedure for modelling flexible metal bellows by the standard beam finite elements in I-DEAS Master Series 6 is presented. In spite of the geometry of the bellows being far from a beam, it is shown that the bellows dynamic behaviour can be modelled by beam elements with the suggested procedure. The model size is reduced by a factor of 100-1000 compared to a shell elements model. This is especially advantageous when the bellows is only a part of for example an exhaust system to be optimised with respect to overall design parameters. In comparison to existing "semi-analytical" methods the standard beam finite elements have the advantages that axial, bending and torsion degrees of freedom are included simultaneously and that the interaction between the bellows and the rest of the system, also modelled by beam or shell finite elements, is easily facilitated. The procedure is verified by experimental results from other investigators.

  • 343. Broman, Göran
    et al.
    Holmberg, John
    Robèrt, Karl-Henrik
    Simplicity Without Reduction: Thinking Upstream Towards the Sustainable Society2000Inngår i: Interfaces, ISSN 0092-2102, E-ISSN 1526-551X, Vol. 30, nr 3, s. 13-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The natural-step framework is used by over 100 organizations, including many global corporations in Europe and the United States, to provide strategic direction for their sustainability initiatives. The framework is built on the concept of simplicity without reduction. Out of respect for complexity we designed it to provide a compass, a guide for strategic direction. The framework consists of a backcasting planning process for sustainable development based on four principles (system conditions) for sustainability. The framework does not prescribe detailed actions. Once an organization understands the framework it identifies and specifies the detailed means by which to achieve the strategy, because it knows its business best. The steps in the planning process are understanding and discussing the system conditions for sustainability, describing and discussing how the company relates to the system conditions in today's situation, creating a vision of how the company will fulfill its customers' needs in the futur e while complying with the system conditions, and specifying a program of actions that will take the company from today's situation to the future vision.

  • 344. Broman, Göran
    et al.
    Jönsson, Anders
    The Nonlinear Behavior of a Rammer Soil Compactor Machine2000Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A theoretical model of a rammer compactor machine is described and its dynamic behaviour is analysed. The differential equations of the model are solved numerically by using standard software. Simulation results are presented as time series, phase plane diagrams, mappings and bifurcation diagrams. The results show that the system is highly nonlinear and indicates that harmonic, subharmonic and chaotic behaviour is present for the parameter variations used. This parameter sensitivity emphasizes the need for this kind of simulations in the product development process.

  • 345. Broman, Göran
    et al.
    Jönsson, Anders
    Hermann, Madeleine
    Determining Dynamic Characteristics of Bellows by Manipulated Beam Finite Elements of Commercial Software2000Inngår i: International Journal of Pressure Vessels and Piping, ISSN 0308-0161, E-ISSN 1879-3541, Vol. 77, nr 8, s. 445-453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A procedure for determining dynamic characteristics of bellows by manipulating certain parameters of the beam finite elements of I-DEAS Master Series 6 is presented. The method will work in any software in which these parameters can be set by the user. Compared to a shell elements model the model size is reduced by at least a factor of 100. This is especially advantageous when the bellows is only a part of a system to be optimised with respect to overall design parameters. Stress in the bellows cannot be predicted by this method, but when the dynamic behaviour is known it can be used as input for stress calculations, if desired. In contrast to existing "semi-analytical" methods this method has the potential of considering axial, bending and torsion degrees of freedom simultaneously, and it facilitates the interaction between the bellows and the rest of the system, also modelled by beam or shell finite elements. The procedure is verified by experimental results from other investigators.

  • 346. Broman, Göran
    et al.
    Jönsson, Anders
    Wall, Johan
    Englund, Thomas
    Introductory Optimisation Study of a Rammer Soil Compactor Machine2001Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Rammer compactor machines perform dynamic soil compaction. The complexity of this machine type makes design optimisation through traditional prototype testing impractical. This has pointed to the need for a theoretical model and simulation procedure for prediction of the dynamic behaviour of the machine and a procedure for optimisation as design parameters are changed during product development. In this paper a theoretical model of the rammer machine in combination with a soil model is described. This multi-body dynamics system is solved numerically. The system is non-linear and chaotic behaviour is possible. This parameter sensitivity emphasises the need for this kind of simulations in the product development process. A fairly regular behaviour is necessary for a predictable and safe operation. Parameter combinations giving too irregular behaviour are non-feasible. The energy transfer rate from the rammer machine into the soil is used as the objective function for optimisation. Multi-start Sequential Quadratic Programming for optimum search is used. To cover the design space well a Uniform Experimental Design is used for selection of starting points. This procedure proves to work well for the problem of this introductory study. The study shows a significant potential for improved compaction capacity although considering only the three design parameters that are most easily changed in practice. Approximately the same optimum is obtained both for operation on soft soil and hard soil, so a good all-round design seems possible. Including this theoretical support in the product development process should make it much more effective in finding optimum designs, also for other machines of similar type.

  • 347. Broman, Göran
    et al.
    Rudenko, Oleg
    Submerged Landau jet: exact solutions, their meaning and application2010Inngår i: Physics Uspekhi, ISSN 1063-7869, E-ISSN 1468-4780, Vol. 53, nr 1, s. 91-98Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Exact hydrodynamic solutions generalizing the Landau submerged jet solution are reviewed. It is shown how exact inviscid solutions can be obtained and how boundary layer viscosity can be included by introducing parabolic coordinates. The use of exact solutions in applied hydrodynamics and acoustics is discussed. A historical perspective on the discovery of a class of exact solutions and on the analysis of their physical meaning is presented.

  • 348. Broman, Göran
    et al.
    Östholm, Stefan
    Mathcad in Teaching Rotor and Structural Dynamics1997Inngår i: International journal of engineering education, ISSN 0949-149X, Vol. 13, nr 6, s. 426-432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes how Mathcad is used to deepen understanding of fundamental aspects in the field of rotor and structural dynamics in two of the undergraduate courses in the education programme of Bachelor of Science in Mechanical Engineering with emphasis on Product Development at the University of Karlskrona/Ronneby, Karlskrona, Sweden. Integrating this mathematical software has clearly given an improved interest for mathematics as well as mechanics among the students.

  • 349. Bru, T.
    et al.
    Waldenström, Paul
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Gutkin, R.
    Olsson, R.
    Vyas, G. M.
    Development of a test method for evaluating the crushing behaviour of unidirectional laminates2017Inngår i: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 51, nr 29, s. 4041-4051Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    More fundamental test methods are needed to assist the development of physically based and truly predictive simulation tools for composite materials under crash conditions. In this paper, a unidirectional flat specimen that can be used to validate the predicted behaviour from a simulation to the physical behaviour in the experiment is developed. A systematic experimental investigation is conducted to evaluate the influence of the trigger geometry on the crushing response by selecting two trigger types and different trigger angles. For longitudinal crushing, the traditional bevel trigger leads to out-of-plane failure by splaying with a limited amount of in-plane fracture, while the proposed trigger achieves a high amount of compressive fragmentation failure. For transverse crushing, the symmetry of the proposed new trigger improves the specimen stability during the crushing process. It is also observed that the weft threads of the unidirectional fabric reinforcement used for the tests have a strong influence on the longitudinal crushing response. The boundary conditions of the test and the information on the specimen failure gleaned from video recordings and microscopic inspections are discussed in order to facilitate a future correlation with modelling results.

  • 350.
    Bruzelius, F
    et al.
    Volvo Technology.
    Svendenius, J
    Haldex.
    Yngve, S
    Volvo Cars.
    Olsson, G
    Saab Automobile.
    Casselgren, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Andersson, M
    Volvo Technology.
    Rönnberg, J
    Saab Automobile.
    Löfving, S.
    Evaluation of tyre to road friction estimators: test methods and metrics2010Inngår i: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 5, nr 2-3, s. 213-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The tyre to road contact friction is one of the most important properties when it comes to manoeuvrability of ground vehicles and information, to driver and vehicle, is of vital importance in critical situations. Different characteristics of different friction estimation methods make it hard to determine and compare performance of estimators. This article is an attempt to define and evaluate the performance of tyre to road friction estimators. The objective of the performance evaluation is to define and grade the performance of estimators based on all sorts of approaches and combinations of these. The result may be used in the context of benchmarking as well as a tool in the development process of the estimator. The test methods and metrics presented are illustrated with a comparative study of three different estimation approaches.

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