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  • 1.
    Amoignon, Olivier
    et al.
    Department of Information Technology, Uppsala University.
    Berggren, Martin
    Department of Information Technology, Uppsala University.
    Discrete adjoint-based shape optimization for an edge-based finite-volume solver2003In: Computational Fluid and Solid Mechanics 2003 / [ed] K. J. Bathe, 2003Conference paper (Refereed)
  • 2.
    Amoignon, Olivier
    et al.
    Department of Information Technology, Uppsala University.
    Pralits, Jan
    Universita di Salerno, Italy.
    Hanifi, Ardeshir
    FOI, Swedish Defence Research Agency, Stockholm.
    Berggren, Martin
    FOI, Swedish Defence Research Agency, Stockholm.
    Henningson, Dan
    FOI, Swedish Defence Research Agency, Stockholm.
    Shape Optimization for Delay of Laminar-Turbulent Transition2006In: AIAA Journal, ISSN 0001-1452, E-ISSN 1533-385X, Vol. 44, no 5, p. 1009-1024Article in journal (Refereed)
  • 3.
    Amoignon, Olivier
    et al.
    Uppsala University, Sweden.
    Pralits, J.O.
    Salermo University, Italy.
    Hanifi, Ardeshir
    FOI, Sweden.
    Berggren, Martin
    FOI, Sweden.
    Henningson, D. S.
    KTH, Sweden.
    Adjoint-Based Shape Optimization for Natural Laminar Flow Design2004In: ERCOFTAC Design Optimization: Methods & Applications / [ed] K.C. Giannakoglou, W. Haase, 2004Conference paper (Refereed)
  • 4.
    Andersson, P.
    et al.
    Department of Mechanics, KTH, Stockholm.
    Berggren, Martin
    FFA, the Aeronautical Research Institute of Sweden.
    Henningson, D.S.
    Department of Mechanics, KTH, Stockholm.
    Optimal Disturbances in Boundary Layers1998In: Computational Methods for Optimal Design and Control, / [ed] J. Borggaard, J. Burns, E. Cliff, and S. Schreck, 1998Conference paper (Refereed)
  • 5.
    Andersson, Paul
    et al.
    FFA, the Aeronautical Research Institute of Sweden, Bromma.
    Berggren, Martin
    FFA, the Aeronautical Research Institute of Sweden, Bromma.
    Henningson, Dan S.
    FFA, the Aeronautical Research Institute of Sweden, Bromma.
    Optimal disturbances and bypass transition in boundary layers1999In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 11, no 1, p. 134-150Article in journal (Refereed)
  • 6. Backman, Anders
    et al.
    Bodin, Kenneth
    Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Lacoursière, Claude
    Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Democratizing CAE with Interactive Multiphysics Simulation and Simulators2012Conference paper (Other academic)
  • 7.
    Berggren, Martin
    et al.
    Department of Information Technology, Uppsala University.
    Bängtsson, Erik
    Department of Information Technology, Uppsala University.
    Noreland, Daniel
    Department of Information Technology, Uppsala University.
    Multifrequency shape optimization of an acoustic horn2003In: Computational Fluid and Solid Mechanics 2003 / [ed] K. J. Bathe, 2003, p. 2204-2207Conference paper (Refereed)
  • 8.
    Berggren, Martin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Lacis, Ugis
    Lindström, Fredrik
    Wadbro, Eddie
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Sound vibration damping optimization with application to the design of speakerphone casings2013In: 10th World Congress of Structural and Multidisciplinary Optimization, Orlando, Florida, USA: Paper id 5569, 2013Conference paper (Refereed)
  • 9.
    Bychkov, Vitaly
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sadek, Jad
    Akkerman, V'yacheslav
    Analysis of flame acceleration in open or vented obstructed pipes2017In: PHYSICAL REVIEW E, ISSN 2470-0045, Vol. 95, no 1, article id 013111Article in journal (Refereed)
    Abstract [en]

    While flame propagation through obstacles is often associated with turbulence and/or shocks, Bychkov et al. [V. Bychkov et al., Phys. Rev. Lett. 101, 164501 (2008)] have revealed a shockless, conceptually laminar mechanism of extremely fast flame acceleration in semiopen obstructed pipes (one end of a pipe is closed; a flame is ignited at the closed end and propagates towards the open one). The acceleration is devoted to a powerful jet flow produced by delayed combustion in the spaces between the obstacles, with turbulence playing only a supplementary role in this process. In the present work, this formulation is extended to pipes with both ends open in order to describe the recent experiments and modeling by Yanez et al. [J. Yanez et al., arXiv: 1208.6453] as well as the simulations by Middha and Hansen [P. Middha and O. R. Hansen, Process Safety Prog. 27, 192 (2008)]. It is demonstrated that flames accelerate strongly in open or vented obstructed pipes and the acceleration mechanism is similar to that in semiopen ones (shockless and laminar), although acceleration is weaker in open pipes. Starting with an inviscid approximation, we subsequently incorporate hydraulic resistance (viscous forces) into the analysis for the sake of comparing its role to that of a jet flow driving acceleration. It is shown that hydraulic resistance is actually not required to drive flame acceleration. In contrast, this is a supplementary effect, which moderates acceleration. On the other hand, viscous forces are nevertheless an important effect because they are responsible for the initial delay occurring before the flame acceleration onset, which is observed in the experiments and simulations. Accounting for this effect provides good agreement between the experiments, modeling, and the present theory.

  • 10.
    Bängtsson, Erik
    et al.
    Department of Information Technology, Uppsala University.
    Noreland, Daniel
    Department of Information Technology, Uppsala University.
    Berggren, Martin
    Department of Information Technology, Uppsala University.
    Shape optimization of an acoustic horn2003In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 192, p. 1533-1571Article in journal (Refereed)
  • 11.
    Chevalier, M.
    et al.
    FFA, the Aeronautical Research Institute of Sweden.
    Berggren, Martin
    FFA, the Aeronautical Research Institute of Sweden.
    Accuray of Gradient Computations in Aerodynamic Shape Optimization2000In: Paper ICAS 2000-2.4.5, 2000Conference paper (Refereed)
  • 12.
    Chevalier, M.
    et al.
    FOI, Stockholm.
    Högberg, M.
    FOI, Stockholm.
    Berggren, Martin
    Sandia National Laboratories.
    Henningson, D. S.
    Department of Mechanics, KTH, Stockholm.
    Linear and Nonlinear Optimal Control in Spatial Boundary Layers2002In: AIAA 3rd Theoretical Fluid Mechanics Meeting, St. Louis, MO.: AIAA Paper 2002-2755, 2002Conference paper (Refereed)
  • 13.
    Edlund, Jeanette
    et al.
    Sveriges lantbruksuniversitet.
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Keramati, Ehsan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    A long-tracked bogie design for forestry machines on soft and rough terrain2013In: Journal of terramechanics, ISSN 0022-4898, E-ISSN 1879-1204, Vol. 50, no 2, p. 73-83Article in journal (Refereed)
    Abstract [en]

    A new design for a tracked forestry machine bogie (long track bogie; LTB) on soft and rough terrain is investigated using nonsmooth multibody dynamics simulation. The new bogie has a big wheel that is connected to and aligned with the chassis main axis. A bogie frame is mounted on the wheel axis but left to rotate freely up to a maximum angle and smaller wheels that also rotate freely are mounted on the frame legs with axes plane parallel to the driving wheel. The wheels are covered by a single conventional forestry machine metal track. The new bogie is shown to have higher mobility and cause less ground damage than a conventional tracked bogie but requires larger torque to create the same traction force as a conventional bogie. The new bogie also gives less acceleration when passing obstacles than the conventional bogie. Additionally, due to the shape and size of the new bogie concept, it can pass wider ditches.

  • 14.
    Edström, Oskar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Konstruktion av automatisk monteringscell2013Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport presenterar ett examensarbete som handlar om en konceptstudie för en monteringscell. Examensarbetet har genomförts av Oskar Edström, student inom maskinteknik på Umeå Universitet, under våren 2013.

    Syftet med arbetet har varit att utveckla en lösning för hur en bussning, som används i Volvos lastvagnar, skall monteras ihop automatiskt i en produktionscell. Arbetet har genomförts i samarbete med uppdragsgivaren HT-Svarv i Kalix

    För att definiera befintliga problem med dagens konstruktion har förstudier, med kartläggning av företagets behov, genomförts. HT-Svarv vill ändra hur bussningen monteras ihop. Detta för att få kortare operationstid under processen och minska behovet av personal vid montering. Före automatisering monterades bussningen ihop manuellt.

    Koncept har genererats i en dialog tillsammans med uppdragsgivaren där man diskuterat olika lösningar för konstruktionen. Koncepten har sedan utvärderats och sållats fram. Vid modellering för koncepten har CAD-programmet Solid Works använts.

    Arbetet resulterade i en lösning där monteringscellen är uppbyggd i tre stycken operationer samt med en efterföljande kontrollstation. För vidareutveckling av valt koncept bör fokus ligga på produktionsoptimering och tester av funktionsprototyper.

  • 15.
    Ek, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Simulation and Evaluation of Models for a Pre In-Die Cutting and an In-Die Cutting Process2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Pre in-die and in-die cutting are processes coupled to metal forming operations. The aim of the thesis was to find, develop, evaluate and validate simulation models for these processes. The goal for pre in-die cutting model was to split a shell segment into multiple segments and for the in-die cutting model to predict cutting tool forces. All models were also supposed to produce physically correct animations. The simulations were made in LS-DYNA and prepared and analyzed in the pre/postprocessor, LS-PrePost. Three simulation models were developed for pre in-die cutting. All with the possibility to split a metal sheet into multiple parts and produce animations of the results. Two models were developed for in-die cutting, the first model uses only shell elements, whereas the other also uses solid elements to represent the metal sheet. The segments essential for the models functionality and how to use them are described in the thesis. Parameter studies were also performed to the evaluate the effects of different variables in the solid model. It was found that many parameters affect the contact stability, dynamic behaviour and cutting tool forces. The information from these studies was used to find an optimal parameter set that was used to correlate the model to experiments. The model was then able to produce results with good correlation to current experiments and to produce physically correct animations. However the experimental data is limited and further experiments need to be carried out to validate the model for more general cases. Finally a method to connect the in-die cutting model to current forming simulations was developed, described and demonstrated.

  • 16.
    Eriksson, Magnus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Avvibrering av drivenhetsupphängning CV90: En studie gjord på BAE systems i Örnsköldsvik2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The noise level on CV90 has always been a big problem, loud noise and great vibrations have been a part of everyday work for the crew. BAE-systems are the developerOf CV90 have started a work with the goal to lower the noise and vibrations in the vehicle. Tests have been made witch shows that the biggest source of the problem is the track. A new track has been constructed, in rubber instead of the traditional steel track. Tests witch have been made on the rubber track shows that nest source of vibrations and noise is the engine and transmission suspension, today the transmission is mutely mounted on the body.The new suspension has been modified from the present, but it has been made bigger so a rubber damper can be fitted between the transmission and the holder. When the rubber damps 1cm it will absorb the force of 2.5G, meanwhile it must hold the force of 5G in every direction. The forces have been simulated by FEM-analysis.A new construction have been made witch fore fill the demands on forces. The natural frequency on the rubber has been calculated to 9.83 Hz, which is around 3 times less the frequency on the engine when the engine is idling(33.33Hz). The idling frequency on the engine is the lowest frequency that will affect the dampers. The transmission will have full damping effect on idling, when the speed raises will the track be the biggest source of vibrations and noise. But on idle this problem will be considerably lowered.

  • 17.
    Gersborg-Hansen, Allan
    et al.
    Department of Mathematics, Technical University of Denmark, Lyngby, Denmark.
    Berggren, Martin
    Department of Information Technology, Uppsala University.
    Dammann, Bernd
    Informatics and Mathematical Modelling, Technical University of Denmark, Lyngby, Denmark.
    Topology optimization of mass distribution problems in Stokes flow2006In: IUTAM Symposium on Topological Design Optimization of Structures, Machines, and Materials. Status and Perspectives / [ed] M. P. Bendsoe, N. Olhoff, O. Sigmund, 2006, p. 365-374Conference paper (Refereed)
  • 18.
    Haciömeroglu, Ömer
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    ERO-Concrete Deconstruction Robot2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    The world is changing. Big cities are attracting more and more population, millions every day and growing. Who among the megacity dwellers would want to wake up in the morning staring at a construction demolition site, dusty, rusty and noisy? The increasing need for an improved infrastructure within the mega cities evokes a big industry of building replacements. The complex combination of building materials and methods is making the de-construction and recycling the demolition waste material very difficult. Today's methods are very complex, time consuming and the end use of the by-products are very limited. Moreover all of these methods are further limited by governmental regulations and laws. These laws are held in order to keep the dynamic city life to be able to cope with the de-construction jobs running around the city. Reinforced concrete being the most celebrated and used structural element, how might we find a smarter way to de-construct it and re-use the byproduct more accurately?

  • 19. Hansbo, Peter
    et al.
    Larson, Mats G.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Continuous/discontinuous finite element modelling of Kirchhoff plate structures in R3 using tangential differential calculus2017In: Computational Mechanics, ISSN 0178-7675, E-ISSN 1432-0924, Vol. 60, no 4, p. 693-702Article in journal (Refereed)
    Abstract [en]

    We employ surface differential calculus to derive models for Kirchhoff plates including in-plane membrane deformations. We also extend our formulation to structures of plates. For solving the resulting set of partial differential equations, we employ a finite element method based on elements that are continuous for the displacements and discontinuous for the rotations, using -elements for the discretisation of the plate as well as for the membrane deformations. Key to the formulation of the method is a convenient definition of jumps and averages of forms that are d-linear in terms of the element edge normals.

  • 20.
    Holmberg Jonsson, Filip
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Konstruktion av vikthållare: Konstruktion av vikthållare och lagerlösning för skivstänger2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this bachelor thesis, a design on a series of weightholders has been developed. The work is carried out on behalf of the company Balticfitness, who has an interest for starting their own production of barebells. These barebells are supposed to compete with other manufacturers on the market. Since this work isn’t a new idea, the work being presented in this report will be based on a market research and dialogues with experts in these areas. The parts and drawings presented in this work have been produced using the CAD software SolidWorks. In the business of barebells and weightholders there are variety of standards that must be kept in order for these barebells to be classified for competitions which have been the frame for this work. The project has delivered a result in which a number of parts and a finished result have been developed. The employer Lars Norberg may with the results which have been produced based on this work, find a suitable manufacturer and start his own production.

  • 21.
    Johansson Ström, Styrbjörn
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Slutväxelhus CV90: Förarbete gällande geometriändringar, materialbyte samt dimensionering av skruvförband.2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Skydd och rörlighet är två viktiga egenskaper hos ett stridsfordon. De är även två motstridiga mål, då ökat skydd ger ökad vikt, vilket minskar terrängframkomligheten. Detta arbete syftar framför allt till att minska vikten på fordonet, genom att minska slutväxelhusets vikt. I arbetet ingår även att undersöka möjliga vägar för att minska reparationskostnader och stilleståndstid genom att förändra infästningen av slutväxelhuset, så att denna ej sliter sönder skrovet vid kollision.  För att minska slutväxelhusets vikt, kommer möjliga geometriändringar och materialbyte från gjutstål till segjärn studeras. Vidare kommer rapporten även undersöka möjligheten att införa en brytpinne i systemet, med syfte att försvaga slutväxelhusets fastsättning. För att detta skall vara möjligt kommer de aktuella lastfallen analyseras. Dessa lastfall ligger till grund för utvärderingar av hållfastheten som sker med hjälp av FEM-programvara.

    Arbetet med geometriändringarna sker iterativt. Framtagandet av olika ändringar sker genom löpande FEM-utvärdering av förslag, med påföljande förändring av förslagen. Ändringarna utvärderas slutligen kollektivt. Studier av litteratur och skrivna samt muntliga källor, ligger till grund för arbetet med materialbytet. Materialens fördelar och nackdelar vägs mot varandra och avslutningsvis genomförs en FEM-utvärdering.     

    Rapporten huvudresultat:

    • 5,6 kg per slutväxelhus kan sparas, om föreslagna geometriändringar införs. Detta utan att funktion eller hållfasthet påverkas negativt.

    • 12,8 kg per hus kan sparas ifall föreslagna geometriändringar samt materialbyte till segjärn genomförs, detta sker dock till priset av ökad utböjning (+24 %). 

    • Infästningen kan försvagas genom att fem av de tolv skruvarna avlägsnas. FEM-beräkningar visar att denna förändring och byte av skruvkvalitet, skapar önskad brytpinne i systemet.

    Ändras geometrierna kommer man behöva ta fram nya gjutformar, priset för dessa måste vägas emot vinsten av geometriförändringen. Geometriändringarna består av två typer, dels ändringar som syftar till att spara vikt genom avlägsnande av material. Den andra typen av ändringar sker i syfte att öka husets motstånd mot böjning. Segjärnet SiSSADI har många fördelar, dock medför den låga E-modulen att utböjningen ökar kraftigt, denna utböjning kan ställa till problem och man måste förhålla sig till detta.   

  • 22.
    Kairento, Karl-Oskar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Konsolidering av bearbetningsfixturer till lyftarmar2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The company Cranab, located in Vindeln, manufactures cranes in varius sizes mostly to forest machines, since a year back they also manufactures cranes to trucks. A crane consists of different components in various sizes such as crane piller, lifting arms, rocker arms, middle boom and inner boom. These components are welded constructions and consists of different details, the different details are produced in a laser cutting process and then welded on to the arm itself. When the arm is complete it is put into a CNC-machine where it is processed. When the arm is ready for the CNC-machine it is placed in a fixture to ensure a more stable processing an mostly to readuce vibrations. The current situation at Cranab is that they use one specific fixture to one specific arm. For this reason it takes a lot of time to change between arms and the fixtures itself takes a lot of place in the workshop. The purpose of this project is to construct a flexible fixture that is able to handle a couple of arms by changing the fixture in a smooth way. A lot of varius factors are important when constructing a fixture that ensures a stable and safe process in the CNC-machine. Cranab are investing a lot of money in a new CNC-machine that will process these arms, the new machine is going to rotate the whole fixture 45 degreese. The fixture that are now used are not able to handle this kind of rotation so except the current requirements the new fixture must be able to hold the whole weight of the arm. During this project the lifting arm to forwarders will be analyzed which is the most complicated part of the crane. The first part of the project will consist of collecting information about the current situation and analyzing the fixtures that are now used, after that the construction of the fixture will be done in the CAD-program Inventor where a koncept will be be developed. The project results in a fixture that can handle eight arms, the current fixtures that are used can only handle a maximum of two arms. With the new fixture, the adjustmets that are necessary when different arms needs to be mounted will be easy to implement and they won’t need a traverse to adjust the fixture. This will make the workprocess of adjusting the fixture much more time efficient. The result is, in comparison with the old fixtures, a clear improvement. Although the project resulted in a raw model of the flexible fixture it is a clear improvement of the existing ones and it is something to continue working with.

  • 23. Klarbring, Anders
    et al.
    Torstenfelt, Bo
    Hansbo, Peter
    Larson, Mats G.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Optimal design of fibre reinforced membrane structures2017In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 56, no 4, p. 781-789Article in journal (Refereed)
    Abstract [en]

    A design problem of finding an optimally stiff membrane structure by selecting one-dimensional fiber reinforcements is formulated and solved. The membrane model is derived in a novel manner from a particular three-dimensional linear elastic orthotropic model by appropriate assumptions. The design problem is given in the form of two minimization statements. After finite element discretization, the separate treatment of each of the two statements follows from classical results and methods of structural optimization: the stiffest orientation of reinforcing fibers coincides with principal stresses and the separate selection of density of fibers is a convex problem that can be solved by optimality criteria iterations. Numerical solutions are shown for two particular configurations. The first for a statically determined structure and the second for a statically undetermined one. The latter shows related but non-unique solutions.

  • 24.
    Lacoursière, Claude
    Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N). Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Regularized, Stabilized, Variational Methods for Multibodies2007In: The 48th Scandinavian Conference on Simulation and Modeling (SIMS 2007) / [ed] Peter Bunus, Dag Fritzson and Claus Führer, Linköping: Linköping University Electronic Press, 2007, p. 40-48Conference paper (Refereed)
    Abstract [en]

    A time-discrete formulation of the variational principle of mechanics is used to construct a novel first order, fixed time step integration method for multibody systems subject to mixed constraints. The new stepper, coined Spook, includes physics motivated constraint regularization and stabilization terms. The stepper is proved to be stable for the case of linear constraints, for non-zero regularization and stabilization parameters. For fixed stabilization value, the regularization can be made arbitrarily small, corresponding to arbitrarily stiff penalty forces. The “relaxed” constraint formulation permits a separation of time scales so that stiff forces are treated as relaxed constraints. Constraint stabilization makes the stiff forces modeled this way strictly dissipative, and thus, the stepper essentially filters out the high oscillations, but is rigorously symplectic for the rest of the motion. Spook solves a single linear system per time step and is insensitive to constraint degeneracies for non-zero regularization. In addition, it keeps the constraint violations within bounds of O(h2), where h is the time step. Because it is derived from the discrete variational principle, the stepping scheme globally preserves the symmetries of the physical system. The combination of these features make Spook a very good choice for interactive simulations. Numerical experiments on simple multibody systems are presented to demonstrate the performance and stability properties.

  • 25.
    Larsson Isfelt, Niclas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utveckling av kabelfordon: Framtagning av konceptstudie för kabelfordon2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Within this project there is two parts; this thesis focuses on the construction of the attachment and the other part reported in another thesis focuses on the hydraulic components which is supposed to control the attachment and also feed the cable in and out.

     

    This project involves the construction of an attachment for mounting cable drums of varying sizes. The purpose is to develop a conceptual study for a custom made attachment that will be mounted on the back of the existing three point hitch on a JCB Fastrac 4220. The aim has been to provide an attachment that is of good user friendliness for operators and meets all the demands for operation.

     

    There will be dynamic loads on the gear, which will cause fatigue of the attachments structure. This has been counteracted by analyzing the stresses in the structure using FE analysis and placing reinforcements in the form of gussets or another beam profile to reduce stress concentrations. The final design has then been simulated for the different operating cases selected (DF). The simpler calculations such as shear stresses in the pins have been done manually, because it is a faster method compared to FEM, especially when there are several different sizes on the pins.

     

    The results show that the tension in the main support at DF1 and DF2 is close to the yield limit, which can be a problem at dynamic load. In the other cases, the stresses are much lower and approach the fatigue limit of the base material. In the welds that have poor fatigue properties, it cannot be concluded that there is endless life. When anlyzing the side support, the DF1-DF5 operating modes show stresses below the fatigue limit of the base material. When it comes to the welds, they have inferior fatigue properties which can cause cracking in the long run. The manual calculations resulted in a maximum von Mises stress of 446 MPa in the pin. With the steel 42CrMo4 chosen instead of the more common S355J2, the fatigue limit is well above the maximum von Mises stress of 446 MPa.

     

    The work resulted in a proposal for a attachment used for mounting cable drums according to the existing requirements. Before delivery to the customer it needs some more work to analyze all the imaginable scenarios and also verify that everything matches to the vehicle.

  • 26.
    Lundberg, Petter
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Investigation of the transient nature of rolling resistance on an operating Heavy Duty Vehicle2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An operating vehicle requires energy to oppose the subjected driving resistances. This energy is supplied via the fuel combustion in the engine. Decreasing the opposing driving resistances for an operating vehicle increases its fuel efficiency: an effect which is highly valued in today’s industry, both from an environmental and economical point of view. Therefore a lot of progress has been made during recent years in the area of fuel efficient vehicles, even though some driving resistances still rises perplexity. These resistances are the air drag Fd generated by the viscous air opposing the vehicles propulsion and the rolling resistance Frr generated mainly by the hysteresis caused by the deformation cycle of the viscoelastic pneumatic tires.

    The energy losses associated with the air drag and rolling resistance account for the majority of the driving resistances facing an operating vehicle, and depends on numerous stochastic and ambient parameters, some of which are highly correlated both within and between the two resistances. To increase the understanding of the driving mechanics behind the energy losses associated with the complexity that is rolling resistance, a set of complete vehicle tests has been carried out. These tests were carried out on the test track Malmby Fairground, using a Scania CV AB developed R440 truck equipped with various sensors connected in one measurement system. Under certain conditions, these parameters can allow for an investigation of the rolling resistance, and a separation of the rolling resistance and air drag via explicit subtraction of the air drag from the measured traction force. This method is possible since the aerodynamic property AHDVCd(β) to some extent can be generated from wind tunnel tests and CFD simulations.

    Two measurement series that enable the above formulated method of separation were designed and carried out, using two separate measurement methods. One which enables the investigation of the transient nature of rolling resistance as it strives for stationarity, where the vehicle is operated under constant velocities i.e. no acceleration, and one using the well established method of coastdown, where no driving torque is applied.

    The drive cycles spanned a range of velocities, which allowed for dynamic and stationary analyses of both the tire temperature- and the velocity dependence of rolling resistance. When analysing the results of the transient analysis, a strong dependence upon tire temperature for given constant low velocity i.e. v ≤ 60 kmh−1 was clearly visible. The indicated dependency showed that the rolling resistance decreased as the tire temperature increased over time at a given velocity, and vice versa, towards a stationary temperature and thereby rolling resistance. The tire temperature evolution from one constant velocity to another, took place well within 50 min to a somewhat stationary value. However, even though the tire temperature had reached stationarity, rolling resistance did not; there seemed to be a delay between stationary tire temperature, and rolling resistance. The results did not indicate any clear trends for v ≥ 60 kmh−1, where the results at v = 80 kmh−1 were chaotic. This suggests that some additional forces were uncompensated for, or that the compensation for air drag was somehow wrongly treated at higher velocities.

    Several factors ruled out any attempts at proposing a new rolling resistance model. These included: the chaotic results for v = 80 kmh−1, the delayed rolling resistance response upon tire temperature stabilization, and the lack of literature support for the observed tendency. The results from the coastdown series on the other hand, showed good agreement with a dynamical model suggested in literature. The stationary temperature behaviour for the considered velocity range at assumed constant condition is also supported in literature.

    Finally, an investigation of the aerodynamic property AHDVCd inspired by ongoing work in ACEA (European Automobile Manufacturers’ Association), was carried out assuming both zero and non-zero air drag at low velocities. The results indicated surprisingly good agreement with wind tunnel measurements, especially when neglecting air drag at low velocities: as suggested by ACEA. 

  • 27.
    Moraeus, Sara
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Integration av bandställ till befintlig skotare: Konceptkonstruktion och analys av kopplingsbalk mellan skotare och bandställ2014Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
  • 28.
    Mårtensson, Daniel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Department of Applied Hydraulics.
    Principles of an automatic brewing machine: By using CodeSys with Raspberry Pi2017Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project will give you a view from another side when it comes to control engineering and mechanical construction in brewing.

    This is a thesis project about principles for an automatic brewing machine. This project started off with prestudy of earlier research results in automatic brewing based on the Arduino platform.

    This project shows principles about mechanical construction and creating a control system by using inexpensive commercial products such as CodeSys and Raspberry Pi.

    The project report begins describing the mechanical construction, how it works and it shows how it looks. The mechanical construction is a tall scaffolding which is the chassis of the brewing machine.

    The history background about brewing is reviewed and the fundamental methods about brewing are described as well. The goal of this project is to present principals by using CodeSys and Raspberry Pi together. Notice that this is not a construction document. This document does not include production wiring diagrams or blueprints – only principles of wiring diagrams and figures of the machine, designed in a CAD software.

    This brewing machine includes a few different kind of control systems to automate the process. The processes are a hops container that can deliver a set of hops in a specific time, motorized whisks to distribute the heat, heat exchanger for cooling down, heating control system and a drain control system.

    The main focus in this project is the mechanical parts, the flow system, the control systems and a discussion about each sub system. Results shows a lot of pictures of the complete system with text that explain the pictures. What was good, what was bad and what could be done better.

  • 29.
    Nordberg, John
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Meshfree elastoplastic solid for non-smooth multi-domain dynamicsManuscript (preprint) (Other academic)
    Abstract [en]

    A method for simulation of elastoplastic solids in multibody systems with nonsmooth and multidomain dynamics is developed. The solid is discretised into pseudo-particles using the meshfree moving least squares method. The particles carry strain and stress tensor variables that are mapped to deformation constraints and constraint forces. The discretised solid model thus fit a unified framework for nonsmooth multidomain dynamics for realtime simulations including strong coupling of rigid multibodies with complex kinematic constraints such as articulation joints, unilateral contacts with dry friction, drivelines and hydraulics. The nonsmooth formulation allow for impulses, due to impacts for instance, to propagate instantly between the rigid multibody and the solid. Plasticity is introduced through an associative perfectly plastic modified Drucker-Prager model. The elastic and plastic dynamics is verified for simple test systems and the capability of simulating tracked terrain vehicles driving on a deformable terrain is demonstrated.

  • 30.
    Noreland, Daniel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Udawalpola, Rajitha
    Department of Information Technology, Uppsala University.
    Berggren, Martin
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    A hybrid scheme for bore design optimization of a brass instrument2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 128, no 3, p. 1391-1400Article in journal (Refereed)
    Abstract [en]

    Thispaper presents how the shape of a brass instrument canbe optimized with respect to its intonation properties. The instrumentis modeled using a hybrid method between a lossy one-dimensionaltransmission line analogy for the slowly flaring part of theinstrument, and a two-dimensional finite element model for the rapidlyflaring part. The optimization employs gradient-based algorithms, and allows fora large number of design variables. Through the use ofan appropriate choice of design variables, the algorithm is capableof rapidly finding horn profiles that are optimal subject tovarious geometric constraints, such as increasing or convex bell flares.It is found that under a convexity constraint, brass windbells that are optimal with respect to an intonation conditioncan be constructed of piecewise conical sections.

  • 31.
    Nyberg, Magnus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Frökarusell: Ett kinematiskt system för time lapse-fotografering av frökapslar med endast en kamera2013Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Swedish University of Agricultural Sciences studies the effects of gene modifications on seeds. When monitoring the growth of these seeds they are using a technique called time lapse photography. It means in this case taking one photo each hour of the seeds, placed on a transparent plastic plate and growing in a medium which supplies nutrition. Thenthese frames are compiled to a movie in which several days of growth are reduced to half a minute.

    A system for this already exists and is in use at SLU here in Umeå, but it only has the capacity for one plate at each time. With this system it is increased to 8 plates at a time. It consists of 8 plate holders made of steel. These are attached to a round aluminium disc, which is attached to a rotary table. This table is driven by a 24 volts stepper motor, controlled by a microprocessor programmed in C.

    The plants cannot be exposed to visible light, so the lightning is realized with infrared diods.

    The camera is controlled from the microprocessor, with a program similar to the function of aintervalometer. The intervalometer is connected directly to the camera for remote controlled photography according to a set time scheme.

    The specifications set in the project plan have been fullfilled and the system is doing what it is designed for.

    My thoughts about improving the system is to make it easier to use. Via a simple display and a few buttons you can input all the variables needed to use it.

  • 32.
    Samuelsson, Ted
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Load Unit Geometry Optimization for Heavy Duty Machinery2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The construction equipment industry is developing at a fast pace, increasing the expectation on the next-generation machines. Wheel loaders and backhoe loaders are part of this evolution and all subsystems in those machines need to be developed to meet the high demands in energy eciency and productivity. One of the most important parts of the wheel loader is the loading unit. This is traditionally designed using highly experienced engineers and CAD software. To simplify the early stages of this process was an optimization tool developed to generate a design outlay. The optimization will minimize the mass of the linkage since unnecessary weight will lower the eciency. The minimum can be found by moving the joints and adjusting the shape of the device. The optimization will also include constraints to assure the correct performance of the linkage. Since there are a high number of design variables, a gradient-based optimization method was used. A finite element solver was also implemented to calculate the forces and stresses in the linkage. The linkages studied in this report are one from a typical wheel loader and one from a backhoe loader. Since these machines are extremely versatile, and used formany diferent tasks, two sets of constraints are compiled. One of the constraint sets yields a linkage suitable for machines only equipped with bucket, while the other results in an all-round linkage suitable for most tools and applications. The optimized linkages are compared to existing devices. The results show that there are some improvements possible and that the software could be used to help designers. However, the optimization problem is hard to solve due to non-smooth constraints functions and numerical instabilities. This issue could be overcome by diferent means, like using automatic diferentiation, a non-gradient based optimization method, decreasing the number of constraints or decreasing the number of design variables.

  • 33.
    Servin, Martin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Lacoursière, Claude
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Rigid body cable for virtual environments2008In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 14, no 4, p. 783-796Article in journal (Refereed)
    Abstract [en]

    The present paper addresses real-time simulation of cables for virtual environments. A faithful physical model based on constrained rigid bodies is introduced and discretized. The performance and stability of the numerical method are analyzed in details and found to meet the requriements of interactive heavy hoisting simulations. The physical model is well behaved in the limit of infinite stiffness as well as in the elastic regime , and the tuning parameters correspond directly to conventional material constants. The integration scheme mixes the well known Störmer-Verlet method for the dynamics equations with the linearly implicit Euler method for the constraint equations and enables physical constraint relaxation and stabilization terms. The technique is shown to have superior numerical stability properties in comparison with either chain link systems, or spring and damper models. Experimental results are presented to show that the method results in stable, real-time simulations. Stability persists for moderately large fixed integration step of $\Delta t = 1/60$ s, with hoisting loads of up to $10^5$ times heavier than the elements of the cable. Further numerical experiments validating the physical model are also presented.

  • 34.
    Servin, Martin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Lacoursière, Claude
    Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Nordfelth, Fredrik
    Bodin, Kenneth
    Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Hybrid, multiresolution wires with massless frictional contacts2011In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 7, no 7, p. 970-982Article in journal (Refereed)
    Abstract [en]

    We describe a method for the visual interactivesimulation of wires contacting with rigid multibodies. Thephysical model used is a hybrid combining lumped elementsand massless quasistatic representations. The latter is basedon a kinematic constraint preserving the total length of thewire along a segmented path which can involve multiple bodiessimultaneously and dry frictional contact nodes used for roping,lassoing and fastening. These nodes provide stick and slidefriction along edges of the contacting geometries. The lumpedelement resolution is adapted dynamically based on local stabilitycriteria, becoming coarser as the tension increases, and up to thepurely kinematic representation. Kinematic segments and contactnodes are added and deleted and propagated based on contactgeometries and dry friction configurations. The method givesdramatic increase on both performance and robustness becauseit quickly decimates superfluous nodes without loosing stability,yet adapts to complex configurations with many contacts andhigh curvature, keeping a fixed, large integration time step.Numerical results demonstrating the performance and stabilityof the adaptive multiresolution scheme are presented along withan array of representative simulation examples illustrating theversatility of the frictional contact model.

  • 35.
    Servin, Martin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Lacoursière, Claude
    Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Wang, Da
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Examining the smooth and nonsmooth discrete element approaches to granular matter2011Conference paper (Other academic)
  • 36.
    Siipilehto Karlsson, William
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Automatisk Kedjespännare: Prototypframtagning av automatisk kedjespännare till kombi-länkarm2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This work is a project aimed at developing a solution to a problem with loose chains in one of Komatsu Forest's forestry machines. The task was to construct an automatic chain tensioner that would tighten the loose chains when needed. Requirements and goals were set for the project. Limitations were established and then a theory was developed for the problem. Based on the theory, a method could be developed to address and solve the problem the best way possible. The project was followed through and the result was four solutions to the problem. The different solutions addressed the problem in different ways but would theoretically solve the problem based on the given theory and limitations. However, one of the solutions was chosen as the best and for that solution, a production base was also taken. If the result were to be continued and a physical prototype would be manufactured, then it could possibly solve the problem of the decaying chains.

  • 37.
    Sundberg, Lars Andreas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Analysis of welded reinforcements on a boom mower: A structural and modal analysis of reinforcement properties on a industrial boom mower2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Road safety is a complicated issue that affects most world economies due to its negative socioeconomic impact. Road safety programs include different programs that cover different areas for minimizing the effects of these impacts. One of these programs focuses road safety against invasion of wildlife into traffic roads. Most economies that heavily include these particular programs, such as Sweden, rely on specific machinery and techniques for clearing road shoulders that allows driver to foresee any possible danger or road invasion in good time. The most common piece of machinery used for covering this type of activity is known as a boom mower. Boom mowers can be pictured as giant lawnmowers that are attached into a long boom crane from wheel loaders or excavators, so they can clear invading vegetation from the road shoulders. Boom mowers suffer from heavy wear due to their dimensions, weight and operating speed which it requires companies to pay extra attention to their construction and choice of materials. Cranab Slagkraft is a Swedish company that has been specialized for providing high quality boom mowers for the last 30 yearsfor clearing vegetation on the Swedish roads. But, despite their higher quality products, these boo mowers are often expensive and complicated to manufacture. For this reason, Cranab has requested a study to minimize the manufacturing burden in order to simplify its production and diminish cost. This research study focuses on the latest components addition into the boom mower construction to assess their performance. For this research, the researcher will put to test the reinforcements of the boom mower’s model SH150 and see what their performance against harmonic vibrations and structural strength against local stresses are. The research follows two complementary analysis. First, a modal analysis on the boom mower’s main structure for evaluating resonance levels at an operating frequency. Second, a structural analysis with idealized conditions at operating speed to determine construction stress resilience. The results in this research reveals that the modal analysis rejects the viability of one group of reinforcements and confirms the implications of the other one. Also, the results reveal that the complicated geometry requires advanced software for providing more conclusive results. In addition, the boom mower’s own geometry and choice of material might play a role in adjusting the harmonic resonance and adjusting the boom mower’s mechanical properties. The latter conclusion should be considered as a theme of study for future research in this same field.

  • 38.
    Udawalpola, Rajitha
    et al.
    Department of Information Technology, Uppsala University.
    Berggren, Martin
    Department of Information Technology, Uppsala University.
    Optimization of an acoustic horn with respect to efficiency and directivity2007In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 73, no 11, p. 1571-1606Article in journal (Refereed)
  • 39.
    Udawalpola, Rajitha
    et al.
    Department of Information Technology, Uppsala University.
    Wadbro, Eddie
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Berggren, Martin
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Optimization of a variable mouth acoustic horn2011In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 85, no 5, p. 591-606Article in journal (Refereed)
    Abstract [en]

    By using boundary shape optimization on the end part of a semi-infinite waveguide for acoustic waves, we design transmission-efficient interfacial devices without imposing an upper bound on the mouth diameter. The boundary element method solves the Helmholtz equation modeling the exterior wave propagation problem. A gradient-based optimization algorithm solves the resulting least-squares problem and the adjoint method provides the necessary gradients. The results demonstrate that there appears to be a natural limit on the optimal mouth diameter.

  • 40.
    Wadbro, Eddie
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Topology Optimization of an Acoustic Horn2006In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 196, p. 420-436Article in journal (Refereed)
  • 41.
    Wadbro, Eddie
    et al.
    Uppsala University, Department of Information Technology, Division of Scientific Computing.
    Berggren, Martin
    Uppsala University, Department of Information Technology, Division of Scientific Computing.
    Topology optimization of wave transducers2006In: Topological Design Optimization of Structures, Machines and Materials: Status and Perspectives / [ed] Martin Philip Bendsøe, Niels Olhoff and Ole Sigmund, 2006, p. 301-310Conference paper (Refereed)
  • 42.
    Wadbro, Eddie
    et al.
    Uppsala University, Department of Information Technology, Division of Scientific Computing.
    Udawalpola, Rajitha
    Uppsala University, Department of Information Technology, Division of Scientific Computing.
    Berggren, Martin
    Uppsala University, Department of Information Technology, Division of Scientific Computing.
    Shape and topology optimization of an acoustic horn-lens combination2007In: Proceedings of Waves 2007: The 8th International Conference on Mathematical and Numerical Aspects of Waves / [ed] N. Biggs et al., Reading, U.K.: University of Reading , 2007, p. 451-453Conference paper (Refereed)
  • 43.
    Wadbro, Eddie
    et al.
    Uppsala University, Department of Information Technology, Division of Scientific Computing.
    Udawalpola, Rajitha
    Uppsala University, Department of Information Technology, Division of Scientific Computing.
    Berggren, Martin
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Shape and topology optimization of an acoustic horn-lens combination2010In: Journal of Computational and Applied Mathematics, ISSN 0377-0427, E-ISSN 1879-1778, Vol. 234, no 6, p. 1781-1787Article in journal (Refereed)
    Abstract [en]

    Using gradient-based optimization combined with numerical solutions of the Helmholtz equation, we design an acoustic device with high transmission efficiency and even directivity throughout a two-octave-wide frequency range. The device consists of a horn, whose flare is subject to boundary shape optimization, together with an area in front of the horn, where solid material arbitrarily can be distributed using topology optimization techniques, effectively creating an acoustic lens.

  • 44.
    Wahlström, Dennis
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Probabilistic Multidisciplinary Design Optimization on a high-pressure sandwich wall in a rocket engine application2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A need to find better achievement has always been required in the space industrythrough time. Advanced technologies are provided to accomplish goals for humanityfor space explorer and space missions, to apprehend answers and widen knowledges. These are the goals of improvement, and in this thesis, is to strive and demandto understand and improve the mass of a space nozzle, utilized in an upperstage of space mission, with an expander cycle engine. The study is carried out by creating design of experiment using Latin HypercubeSampling (LHS) with a consideration to number of design and simulation expense.A surrogate model based optimization with Multidisciplinary Design Optimization(MDO) method for two different approaches, Analytical Target Cascading (ATC) and Multidisciplinary Feasible (MDF) are used for comparison and emend the conclusion.

    In the optimization, three different limitations are being investigated, designspace limit, industrial limit and industrial limit with tolerance. Optimized results have shown an incompatibility between two optimization approaches, ATC and MDF which are expected to be similar, but for the two limitations, design space limit and industrial limit appear to be less agreeable. The ATC formalist in this case dictates by the main objective, where the children/subproblems only focus to find a solution that satisfies the main objective and its constraint. For the MDF, the main objective function is described as a single function and solved subject to all the constraints. Furthermore, the problem is not divided into subproblems as in the ATC.

    Surrogate model based optimization, its solution influences by the accuracy ofthe model, and this is being investigated with another DoE. A DoE of the full factorial analysis is created and selected to study in a region near the optimal solution.In such region, the result has evidently shown to be quite accurate for almost allthe surrogate models, except for max temperature, damage and strain at the hottestregion, with the largest common impact on inner wall thickness of the space nozzle. Results of the new structure of the space nozzle have shown an improvement of mass by ≈ 50%, ≈ 15% and ≈ -4%, for the three different limitations, design spacelimit, industrial limit and industrial limit with tolerance, relative to a reference value,and ≈ 10%, ≈ 35% and ≈ 25% cheaper to manufacture accordingly to the defined producibility model.

  • 45.
    Wang, Da
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Mickelsson, Kjell-Ove
    Outlet design optimization based on large-scale nonsmooth DEM simulation2011Conference paper (Other academic)
    Abstract [en]

    We consider the application of a nonsmooth discrete element method (NDEM) [1-3] to geometricdesign optimization of a balling drum outlet used in production of iron ore pellets. The geometricdesign optimization problem is based on the need for spatially and temporally homogeneous flow ofpellets from the balling drum onto a wide belt conveyor feeding a roller sieve. Homogeneous pelletflow makes sieving most efficient and facilitates good control in the hardening furnace. The model ofthe pellet material and balling drum are specified in a NDEM framework. The simulation andanalysis procedure is described. A material flow profile in terms of design parameters is computedfrom simulation data and used for solving the design optimization problem. The solution is comparedwith different designs used in a real production plants. It is demonstrated that the method can clearlydistinguish between the original and improved design in that plant. The uncertainty in the optimaldesign parameters is discussed and put in relation to the assumptions and approximations behind the particular NDEM that is used. Proposal for how to improve and validate the material and ballingdrum model is given.

    The particular NDEM is described in more detail in an accompanying paper [4] where the method isalso contrasted to the more conventional smooth discrete element method (DEM) [5]. The nonsmoothapproach allows for time integration using time-steps much larger than the characteristic elasticresponse time. Given an efficient solver and that the system and application justifies the nonsmoothapproximation a considerable speed-up can be achieved, though it should be recognized that this issignificantly problem dependent. The current paper includes analysis of the computational efficiencyof the NDEM approach to the particular case of balling drum outlet flow analysis with a given errortolerance. Time estimates of a corresponding smooth DEM approach is provided for comparison.

  • 46.
    Welander, Simon
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Serviceförbättringar av GTC-200MSS2013Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Som ett sista arbete på högskoleingenjörsutbildningen i maskinteknik på Umeå universitet så har jag sett över servicevänligheten på ett reservkraftsaggregat. Attacus Power AB har stått som värd för detta arbete och även tillhandahållit arbetsplats under utförandet.

    Ett reservkraftsaggregat är ofta en dieseldriven motor kopplad till en generator som alstrar ström. Denna ström kan sedan användas för att driva sjukhus eller liknande vid ett eventuellt strömavbrott.

    Modellen som skulle ses över heter GTC-200MSS och den är en extra tyst modell avsedd för platser som filminspelningar och liknande där ljudnivån är en viktig faktor.

    Det jag skulle utföra var att försöka hitta en lösning där motor och generator, med så litet ingrepp som möjligt, kunde tas ut för underhåll.

    Arbetet började med att olika lösningsförslag togs fram. Allt från att vicka av hela höljet, till en ny utformning av modellen. Efter att alla förslag presenterats och gåtts igenom med inblandade på företaget, så beslutades att en lösning där en truck eller liknande med hjälp av sina gafflar kunna lyfta ut motor och generator var den bästa lösningen.

    För att göra det enkelt för de som skulle utföra ingreppet så gjordes en enkel manual.

    En modell togs fram där truckens gafflar legat till grund för utförandet samt dess belastningsfall. Genom att lägga till en enkel dropplåt under motor och generator ökas trivsamheten för de som ska arbeta med maskinen efter ett par år då maskinen blir lättare att hålla ren.

    För att inte bygga för mycket på höjden beslutades att göra dörren så stor som det gick och sedan även sänka dörren så att den nedre dörrkarmen inte skulle bli ett hinder för gafflarna.

    En FEM-analys gjordes för att se om konstruktionen skulle klara av de olika belastningsfallen. Det visade sig att så inte var fallet utan en förstärkning var ett måste.

    Elskåpet placerades om för att inte vara i vägen för den högre generatorplaceringen. Detta var inte optimalt då installationen kommer försvåras eftersom väggen som den nu ska fästas på installeras sist med höljet.

    Om denna rapport skulle göras om, så skulle större vikt läggas på att se om generatordörren kunnat användas som en lösning. Detta skulle medföra fördelar som att elskåpet inte skulle behöva flyttas samt att tyngdpunkt av generatorn och motorn skulle hamna närmare trucken vid ett lyft.

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