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  • 1.
    Ahlström, Johan
    et al.
    RISE, Swerea, KIMAB.
    Tidblad, Johan
    RISE, Swerea, KIMAB. RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Sederholm, Bror
    RISE, Swerea, KIMAB.
    Wadsö, L.
    Lund University, Sweden.
    Influence of chloride and moisture content on steel rebar corrosion in concrete2016In: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 67, no 10, p. 1049-1058Article in journal (Refereed)
    Abstract [en]

    Reinforced mortar samples were exposed in humidity chambers with different relative humidity or exposed in cyclic moisture conditions. The rebars were in an “as received” condition meaning that the preexisting oxide scale were intact. The lowest chloride concentration that initiated corrosion was 1% Cl− by mass of cement, corrosion was then observed for samples exposed at 97% relative humidity. It is suggested that the corrosion rate decreases when samples are exposed to a relative humidity lower than 97%. The results indicate that threshold levels should be evaluated at rather humid conditions (97%) despite the fact that the maximum corrosion rate at higher chloride levels is observed in the interval 91–94%. For samples exposed to cyclic moisture conditions, a lower chloride concentration was needed to initiate corrosion compared to samples exposed in static moisture conditions.

  • 2.
    Aitomäki, Yvonne
    et al.
    RISE, Swerea, SICOMP.
    Hagström, Bengt
    RISE, Swerea, IVF.
    Långström, Runar
    RISE, Swerea, SICOMP.
    Fernberg, Patrik
    RISE, Swerea, SICOMP.
    Novel reactive bicomponent fibres: Material in composite manufacturing2012In: Journal of Nanostructured Polymers and Nanocomposites, ISSN 1790-4439, Vol. 8, no 1, p. 5-11Article in journal (Refereed)
    Abstract [en]

    The hypotheses that reactive uncured, thermoset bicomponent fibres can be prepared and mixed with reinforcing fibres and ultimately used in preparation of a composite was tested and is described. It is thought that such fibres have the two potential advantages: (1) to enable manufacturing with particle doped resins e.g. nanocomposites which add functionality to composites and (2) increased efficiency of structural composite manufacturing by increasing the level of automation. The structure of the thermoset fibres comprises of a sheath of thermoplastic and a core of uncured thermoset resin. Once manufactured, the fibres were wound with a reinforced fibre onto a plate, consolidated and cured. The resulting composite was examined and compared to other composites made with the same manufacturing method from commercially available materials. The results show that a laminate can be produced using these reactive bicomponent fibres. The resin system successfully impregnates the reinforcing carbon fibres and that the thermoplastic separates from the epoxy resin system during consolidation. In comparison to reference material, the bicomponent laminate shows promising characteristics. However, the processes developed are currently on a lab-scale and considerable improvement of various bicomponent fibre properties, such as the strength, are required before the technology can be used on a larger scale.

  • 3.
    Alipour, Y.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Viklund, Peter
    RISE, Swerea, KIMAB.
    Henderson, P.
    Vattenfall, Sweden.
    The analysis of furnace wall deposits in a low-NOx waste wood-fired bubbling fluidised bed boiler2012In: VGB PowerTech, ISSN 1435-3199, Vol. 92, no 12, p. 96-100Article in journal (Refereed)
    Abstract [en]

    Increasing use is being made of biomass as fuel for electricity production as the price of natural wood continues to rise. Therefore, more use is being made of waste wood (recycled wood). However, waste wood contains more chlorine, zinc and lead, which are believed to increase corrosion rates. Corrosion problems have occurred on the furnace walls of a fluidised bed boiler firing 100 % waste wood under low-NOx conditions. The deposits have been collected and analysed in order to understand the impact of the fuel.

  • 4.
    Andersons, J.
    et al.
    University of Latvia, Latvia.
    Modniks, J.
    University of Latvia, Latvia; Ventspils University College, Latvia.
    Joffe, Roberts
    RISE, Swerea, SICOMP. Luleå University of Technology, Sweden.
    Madsen, B.
    DTU Technical University of Denmark, Denmark.
    Nättinen, K.
    Bemis Flexible Packaging Europe, Finland.
    Apparent interfacial shear strength of short-flax-fiber/starch acetate composites2016In: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 64, p. 78-85Article in journal (Refereed)
    Abstract [en]

    The paper deals with an indirect industry-friendly method for identification of the interfacial shear strength (IFSS) in a fully bio-based composite. The IFSS of flax fiber/starch acetate is evaluated by a modified Bowyer and Bader method based on an analysis of the stress-strain curve of a short-fiber-reinforced composite in tension. A shear lag model is developed for the tensile stress-strain response of short-fiber-reinforced composites allowing for an elastic-perfectly plastic stress transfer. Composites with different fiber volume fractions and a variable content of plasticizer have been analyzed. The apparent IFSS of flax/starch acetate is within the range of 5.5-20.5 MPa, depending on composition of the material. The IFSS is found to be greater for composites with a higher fiber loading and to decrease with increasing content of plasticizer. The IFSS is equal or greater than the yield strength of the neat polymer, suggesting good adhesion, as expected for the chemically compatible constituents.

  • 5.
    Andersson, J.
    et al.
    RISE, Swerea, KIMAB.
    Persson, Daniel
    RISE, Swerea, KIMAB.
    Jönsson, D.
    Scania CV, Sweden.
    Tornberg, Malin
    RISE, Swerea, KIMAB.
    Lindh-Ulmgren, Eva
    RISE, Swerea, KIMAB.
    Degradation of carbon fiber reinforced composites induced by galvanic coupling to metallic materials2015In: European Corrosion Congress, EUROCORR 2015, Austrian Society for Metallurgy and Materials (ASMET) , 2015Conference paper (Refereed)
  • 6.
    Andersson, O.
    et al.
    KTH Royal Institute of Technology, Sweden.
    Semere, D.
    KTH Royal Institute of Technology, Sweden.
    Melander, Arne
    RISE, Swerea, KIMAB. KTH Royal Institute of Technology, Sweden.
    Arvidsson, M.
    Volvo Car Corporation, Sweden.
    Lindberg, B.
    KTH Royal Institute of Technology, Sweden.
    Digitalization of Process Planning of Spot Welding in Body-in-white2016In: Procedia CIRP, Elsevier B.V. , 2016, p. 618-623Conference paper (Refereed)
    Abstract [en]

    Process planning of spot welding for body-in-white automobile structures involves several experimental (physical) welding trials to set the process parameters. These experimental trials are crucial in ensuring the quality and efficiency of the process. However, due to the iterative nature of the work, running several experiments is costly and time consuming prolonging the overall development cost and time significantly. To minimize the cost and time, replacing the physical tests by digital (virtual) tests is an established approach although not often applied for spot welding. However, for a long chain of development process with several iterative loops, this is not a trivial task considering the availability of information and continuity of the work flow. This paper reports the work and results of an industrial case study conducted on spot welding of a body-in-white car pillar in a Swedish auto manufacturer. The aim of the study is to investigate and propose the necessary conditions required to replace a physical test by virtual tests in terms of validity and expedited execution of the process. Information sharing, knowledge reuse and streamlining the work flow have found to be critical condition for valid and rapid virtual tests. © 2016 The Authors.

  • 7.
    Ankerfors, Caroline
    et al.
    RISE, Swerea, KIMAB.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Polyelectrolyte complexes for tailoring of wood fibre surfaces2014In: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 256, p. 1-24Article in journal (Refereed)
    Abstract [en]

    The use of polyelectrolyte complexes (PECs) provides new opportunities for surface engineering of solid particles in aqueous environments to functionalize the solids either for use in interactive products or to tailor their adhesive interactions in the dry and/or wet state. This chapter describes the use of PECs in paper-making applications where the PECs are used for tailoring the surfaces of wood-based fibres. Initially a detailed description of the adsorption process is given, in more general terms, and in this respect both in situ formed and pre-formed complexes are considered. When using in situ formed complexes, which were intentionally formed by the addition of oppositely charged polymers, it was established that the order of addition of the two polyelectrolytes was important, and by adding the polycation first a more extensive fibre flocculation was found. PECs can also form in situ by the interaction between polyelectrolytes added and polyelectrolytes already present in the fibre suspension originating from the wood material, e.g. lignosulphonates or hemicelluloses. In this respect the complexation can be detrimental for process efficiency and/or product quality depending on the charge balance between the components, and when using the PECs for fibre engineering it is not recommended to rely on in situ PEC formation. Instead the PECs should be pre-formed before addition to the fibres. The use of pre-formed PECs in the paper-making process is described as three sub-processes: PEC formation, adsorption onto surfaces, and the effect on the adhesion between surfaces. The addition of PECs, and adsorption to the fibres, prior to formation of the paper network structure has shown to result in a significant increase in joint strength between the fibres and to an increased strength of the paper made from the fibres. The increased joint strength between the fibres is due to both an increased molecular contact area between the fibres and an increased molecular adhesion. The increased paper strength is also a result of an increased number of fibre/fibre contacts/unit volume of the paper network. 

  • 8.
    Apruzzese, Paola
    et al.
    Imperial College London, UK.
    Olsson, Robin
    RISE, Swerea, SICOMP.
    Falzon, Brian
    Monash University, Australia.
    Modelling the postbuckling behaviour of impacted composite structures2009In: Proc. 17th Int. Conf. on Composite Materials (ICCM-17), 2009, article id F7:11Conference paper (Refereed)
    Abstract [en]

    Two approaches to modelling the effects of embedded defects and impact damage in composite aerostructures are presented. These differ in the manner in which the damage is represented; one as an equivalent delamination and the other as a soft inclusion with non-linear homogenized material properties. These techniques are applied to study the effects of defects and impact damage on the performance of composite panels.

  • 9.
    Asp, Lars Erik
    et al.
    RISE, Swerea, SICOMP. Chalmers University of Technology, Sweden.
    Greenhalgh, E. S.
    Imperial College, UK.
    Structural power composites2014In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 101, p. 41-61Article in journal (Refereed)
    Abstract [en]

    This paper introduces the concept of structural power composite materials and their possible devices and the rationale for developing them. The paper presents a comprehensive review of the state-of-the-art, highlighting achievements related to structural battery and supercapacitor devices. The research areas addressed in detail for the two types of material devices include: carbon fibre electrodes, structural separators, multifunctional matrix materials, device architectures and material functionalization. Material characterisation, fabrication and validation are also discussed. The paper culminates in a detailed description of scientific challenges, both generic as well as device specific, that call for further research. Particular reference is given to work performed in national and European research projects under the leadership of the authors, who are able to provide a unique insight into this newly emerging and exciting field.

  • 10.
    Asp, Leif
    et al.
    RISE, Swerea, SICOMP. Chalmers University of Technology, Sweden.
    Leijonmarck, Simon
    RISE, Swerea, SICOMP. KTH Royal Institute of Technology, Sweden.
    Carlson, Tony
    RISE, Swerea, SICOMP.
    Lindbergh, G.
    KTH Royal Institute of Technology, Sweden.
    Realisation of structural battery composite materials2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    This paper introduces the concept of structural battery composite materials and their possible devices and the rationale for developing them. The paper presents an overview of the research performed in Sweden on a novel structural battery composite material. The research areas addressed include: carbon fibre electrodes, structural separators, multifunctional matrix materials, device architectures and material functionalization. Material characterization, fabrication and validation are also discussed. The paper focuses on a patented battery composite material technology. Here, carbon fibres are employed as combined negative battery electrodes and reinforcement, coated with a solid polymer electrolyte working simultaneously as electrolyte and separator with ability to transfer mechanical loads. The coated fibres are distributed in a conductive positive cathode material on an aluminium electron collector film. Efficient Li-ion transport between the electrodes is achieved by the solid polymer electrolyte coating being only a few hundred nanometres thick. Finally some outstanding scientific and engineering challenges are discussed. Such challenges, calling for further research are related to manufacture, development of new solid polymer electrolytes for improved multifunctionality and the lack of material models. 

  • 11.
    Bachinger, Angelika
    et al.
    RISE, Swerea, SICOMP.
    Marklund, Erik
    RISE, Swerea, SICOMP. Luleå University of Technology, Sweden.
    André, Alann
    RISE, Swerea, SICOMP.
    Hellström, Peter
    RISE, Swerea, SICOMP.
    Rössler, Joraine
    RISE, Swerea, SICOMP. Chalmers University of Technology, Sweden.
    Asp, Leif
    RISE, Swerea, SICOMP. Chalmers University of Technology, Sweden.
    Materials with variable stiffness2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    In this study different concepts to attain a material that can reduce its stiffness upon external stimulation were evaluated regarding their suitability for traffic safety applications. All concepts rely on resistive heating of a carbon fibre reinforcement upon application of electric current through the fibres. The stiffness reduction is achieved by a phase transformation due to heating of the material. The phase transformation takes place either in a thermoplastic interphase, in a thermoplastic matrix or in a thermoset matrix, depending on the concept. The different concepts were studied regarding their thermomechanical and processing properties and their ability to reduce their stiffness upon application of an electric current was tested. Moreover, the materials were evaluated regarding their potential for fast activation, which is crucial for applications in traffic safety. Stiffness-reduction was achieved upon application of an electric current, where the activation temperature was between 60 and 120°C and the extent of stiffness-reduction varied between 50 and 90%, depending on the material. The response time was found to depend to a large extent on the amount of material, which leads to the conclusion that smart design solutions are required for larger parts. It is concluded that the concepts vary in their thermal, mechanical and processing properties as well as in their extent of stiffness-reduction upon activation. The results presented in this work prove the feasibility of the studied materials for traffic safety applications and the concepts allow further optimization of the materials for specific applications

  • 12.
    Bachinger, Angelika
    et al.
    RISE, Swerea, SICOMP.
    Rössler, Joraine
    RISE, Swerea, SICOMP. Chalmers University of Technology, Sweden.
    Asp, Lars Erik
    RISE, Swerea, SICOMP. Chalmers University of Technology, Sweden.
    Electrocoating of carbon fibres at ambient conditions2016In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 91, p. 94-102Article in journal (Refereed)
    Abstract [en]

    Electrocoating at constant current is less sensitive to moisture and oxygen than electrocoating at controlled potential, which makes it more interesting for industrial implementation. The galvanostatic electrocoating of carbon fibres with Poly(methylmethacrylate) (PMMA) was therefore studied and compared to the well researched potentiostatic electrocoating procedure. The influence of different experimental parameters on the coating efficiency was investigated in order to identify the mechanisms that are involved in the cathodic electrocoating at constant current. It could be confirmed that the involved mechanisms differ from potentiostatic electrocoating and it was found that galvanostatic electrocoating is more efficient at ambient conditions compared to potentiostatic electrocoating. Polymer layers that cover the entire carbon fibre surface could be achieved in a continuous process by galvanostatic electrocoating under ambient conditions. 

  • 13.
    Bein, T.
    et al.
    Fraunhofer LBF, Germany.
    Mayer, D.
    Fraunhofer LBF, Germany.
    Hagebeuker, L.
    Institut für Kraftfahrzeuge, Germany.
    Bachinger, Angelika
    RISE, Swerea, SICOMP.
    Bassan, D.
    C.R.F. S.C.p.A, Italy.
    Pluymers, B.
    KU Leuven, Belgium.
    Delogu, M.
    Università degli Studi di Firenze, IItaly.
    Enhanced Lightweight Design - First Results of the FP7 Project ENLIGHT2016In: Transportation Research Procedia, ISSN 2324-9935, E-ISSN 2352-1465, p. 1031-1040Article in journal (Refereed)
    Abstract [en]

    The European Green Vehicle project ENLIGHT aims to advance highly innovative lightweight material technologies for application in structural vehicle parts of future volume produced Electric Vehicles (EVs) along four axes: performance, manufacturability, cost effectiveness and lifecycle footprint. The main target is to develop viable and sustainable solutions for medium production volume up to 50.000 EVs destined to reach the market in the next 8-12 years. The specific objectives of the ENLIGHT project are on holistic and integrated conceptual design and manufacturing concerning how the technologies and materials addressed can be combined into a representative medium-volume EV. The solutions will be demonstrated in five modules: a front module and central floor module, a front door, a sub-frame and suspension system as well as a cross-car beam. In this paper, a summary of the major results obtained up to the 3rd project year will be presented. © 2016 The Authors.

  • 14.
    Bellqvist, David
    et al.
    RISE, Swerea, MEFOS.
    Wang, Chuan
    RISE, Swerea, MEFOS.
    Nilsson, Leif
    SSAB EMEA, Sweden.
    Techno-economic analysis of low temperature waste heat recovery and utilization at an integrated steel plant in Sweden2014In: Chemical Engineering Transactions, ISSN 1974-9791, E-ISSN 2283-9216, Vol. 39, no Special Issue, p. 67-72Article in journal (Refereed)
    Abstract [en]

    Energy consumption and CO2 emissions is an ever-present issue for energy intensive industries, such as the steel industry. The work for reducing the environmental impact is a strong interest among the governments in Europe and the 20-20-20 targets, decided by the EU, set the targets for the year 2020 to increase energy efficiency by 20 %, reduce greenhouse gas emissions by 20 %, and increase the use of renewable energy to 20 %. It is therefore important for the steel industry, and other industries, to continuously be working on development of concepts for decreasing the environmental impact, which are also financially viable. This paper presents the work that has been conducted in order to evaluate the potential benefits regarding energy- & cost saving and CO2 mitigation, when recovering and utilizing low temperature waste heat at an integrated steel plant in Sweden, SSAB EMEA Lulea. In order to achieve a holistic overview of the plant a process integration approach is applied to evaluate the effects that occur when applying technologies for waste heat recovery. The results indicate a potential for energy saving of 1.9 %, and a corresponding CO2 mitigation potential of 1.5 %. The calculated payback time for the applied waste heat recovery concepts, which is based on specific methods and economic assumptions, range between 1.5 - 7.0 y. 

  • 15.
    Ben Kahla, H.
    et al.
    Luleå University of Technology, Sweden.
    Varna, J.
    Luleå University of Technology, Sweden.
    Pupurs, Andrejs
    RISE, Swerea, SICOMP. Luleå University of Technology, Sweden.
    Microcracking in layers of composite laminates in cyclic loading with tensile transverse stress component in layers2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    Intralaminar cracking in layers of a quasi-isotropic carbon fiber NCF laminate in tension-tension cyclic loading is studied experimentally. Methodology based on modified Weibull analysis is suggested to combine quasi-static and fatigue testing to identify parameters in the crack density growth model. The validity of the assumptions for the given material is experimentally confirmed. The suggested methodology can lead to significant time and material savings in composites fatigue behaviour characterization. 

  • 16.
    Bengtson, Arne
    et al.
    RISE, Swerea, KIMAB.
    Hildebrand, L.
    Technical University of Dortmund, Germany.
    Expert systems for prediction of corrosion properities of Zn-based coatings from the chemical analysis2012In: Yejin Fenxi/Metallurgical Analysis, ISSN 1000-7571, Vol. 32, no 4, p. 1-5Article in journal (Refereed)
    Abstract [en]

    The purpose of the work is to develop a general method, to predict the corrosion resistance of Zn-based coatings, expressed as total mass loss in an accelerated salt spray test. The method is to be based on just three analytical parameters; the total coating weights of Zn, Al and Mg. The reason for this restriction is that determination of these three parameters is possible in on-line analysis. The predicted corrosion resistance could then be included in a process/quality control system. Accelerated corrosion tests have been carried out by Swerea KIMAB IC (Institut de Corrosion) in Brest, and CRM in Belgium. Test were run according to the Renault ECC1 test D172028/-C (12 weeks), and with an accelerated cyclic corrosion test developed by CRM. The materials were divided into four corrosion classes according to total mass loss. All corrosion experiments show clearly the well documented positive influence of magnesium and aluminium. In relation to the masses of these elements in the coatings, the influence of both elements is considerably higher than the influence of zinc alone. For this reason, a new quantity is introduced, called "equivalent Zn coating weight". This quantity is a linear combination of the coating weights of zinc, aluminium and magnesium. A model for prediction of corrosion resistance was developed with the expert system, based on a combination of regression analysis and a "decision tree" algorithm. The model was able to correctly classify 25 out of 27 materials based on just the three analytical parameters mentioned above: the total coating weights of zinc, aluminium and magnesium. In conclusion, the approach shows that an accurate prediction of the corrosion behaviour is possible even on-line. For purposes of material development, the expert system can also be expanded to include additional analytical parameters.

  • 17.
    Bengtson, Arne
    et al.
    RISE, Swerea, KIMAB.
    Sedlakova, Miroslva
    RISE, Swerea, KIMAB.
    Didriksson, R.
    SSAB, Sweden.
    Rapid inclusion characterisation by pulse distribution analysis optical emission spectroscopy-recent development2013In: Yejin Fenxi/Metallurgical Analysis, ISSN 1000-7571, Vol. 33, no 1, p. 7-12Article in journal (Refereed)
    Abstract [en]

    The purpose of the work is to further develop and validate the optical emission method pulse distribution analysis (PDA) for rapid inclusion characterisation in steel production. The experimental work was focused on investigation of several operational parameters: spark energy, spark frequency and time gating of signal acquisition. The results showed that a low spark energy improves the detection limit, but at the expense of measuring statistics due to a smaller sample volume. The measuring frequency proved to have no significant influence on the analytical results, but several existing instruments cannot handle the highest spark frequencies above about 300 Hz in PDA mode due to limitations in the electronics. Investigation of time gating (TRS) gave only a marginal improvement in the detection limit of Si outliers above the metallic content. The work also revealed that there is a risk to detect "false" outliers due to asymmetric intensity distributions. This has resulted in the development of more advanced algorithms for outlier detection, increasing the accuracy of the method. Another limitation found is that the particle number density must not exceed about 10 000 inclusions/mm3 for the method to effectively detect single inclusions. A method to overcome this limitation has been suggested, but not yet evaluated. The accuracy of quantitative determination of the Al content in inclusions has been verified by reference methods. In conclusion, it has been demonstrated that state-of-the-art PDA is a very powerful technique for rapid inclusion characterisation in steels. Furthermore, the speed of analysis is sufficiently high for process feedback and controllable.

  • 18.
    Bjelkemyr, Marcus
    et al.
    RISE, Swerea, IVF.
    Shahbazi, Sasha
    RISE, Swerea, IVF.
    Jönsson, C.
    Mälardalen University, Sweden.
    Wiktorsson, Magnus
    RISE, Swerea, IVF.
    Individuals’ perception of which materials are most important to recycle2015In: IFIP WG 5.7 International Conference on Advances in Production Management Systems, APMS 2015, Springer New York LLC , 2015, p. 723-729Conference paper (Refereed)
    Abstract [en]

    In this study, we have asked respondents to rank ten different waste fractions that are both common in manufacturing industry and easily recognizable. The purpose of the study has been to clarify to what extent individuals are able to identify the waste fractions that are most important to recycle from an environmental perspective. The individuals’ perception has then been correlated with a life cycle assessment of the ten materials. In addition, the respondents were also asked to rank the fractions according to cost. The results show that metals are consistently considered most important to recycle, and plastics are commonly among the top five amongst the ten waste fractions together with glass. The cellulose based fractions, cotton, and compost are commonly rated low. In addition, there is a perceived correlation between the environmental and economic impact.

  • 19.
    Bjornsson, A.
    et al.
    Linköping University, Sweden.
    Lindback, J. -E
    Saab Aerostructures, Sweden.
    Eklund, Daniel
    RISE, Swerea, SICOMP.
    Jonsson, Marie
    RISE, Swerea, SICOMP.
    Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry2015In: SAE International Journal of Materials & Manufacturing, ISSN 1946-3979, E-ISSN 1946-3987, Vol. 9, no 1, p. 68-74Article in journal (Refereed)
    Abstract [en]

    With an increased use of composite materials within the aerospace industry follows a need for rational and cost-effective methods for composite manufacturing. Manual operations are still common for low to medium manufacturing volumes and complex products. Manual operations can for example be found in material handling, when picking prepreg plies from a cutter table and stacking them to form a plane laminate in preparation for a subsequent forming operation. Stacking operations of this kind often involves a great number of different ply geometries and removal of backing paper and other protecting materials like plastic. In this paper two different demonstrator cells for automated picking of prepreg plies and stacking of plane laminates are presented. One demonstrator is utilizing a standard industrial robot and an advanced end-effector to handle the ply variants. The other demonstrator is using a dual arm robot which allow for simpler end-effector design. In combination with a previously developed system for automated removal of backing papers both systems have shown to be capable of automatically picking prepreg plies from a plane surface and stack them to generate a flat multistack laminate. The dual arm approach has shown advantageous since it result in simpler end-effector design and a successive lay down sequence that result in good adhesion between the plies in the laminate. null.

  • 20.
    Björnsson, A.
    et al.
    Linköping University, Sweden.
    Jonsson, Marie
    RISE, Swerea, SICOMP.
    Johansen, K.
    Linköping University, Sweden.
    Automation of composite manufacturing using off-the-shelf solutions; three cases from the aerospace industry2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    With an increased use of composite materials follows a need for rational, cost-efficient manufacturing processes. This paper explores how off-the-shelf solutions, developed for other purposes than composite manufacturing, can be used to build systems for automated composite manufacturing. Three demonstrators, each of them dealing with a specific type of material and all of them representing different manufacturing technologies for automated composite manufacturing, are presented and analyzed to find aspects that affect the ability to use off-the-shelf solutions. The three demonstrators target low to medium manufacturing volumes of complex products and they have been developed in collaboration with industrial partners within the aerospace industry. The conclusions drawn from the development of the demonstrators are that it is technically feasible to use off-the-shelf solutions in the three cases while adhering to the high quality standards of the industry. Furthermore three groups of aspects, quality aspects, product aspects and system aspects, which affect the ability to use off-the-shelf solutions for automated composite manufacturing, are identified.

  • 21.
    Björnsson, A.
    et al.
    Linköping University, Sweden.
    Jonsson, Marie
    RISE, Swerea, SICOMP.
    Lindbäck, J. E.
    SSAB, Sweden.
    Åkermo, M.
    KTH Royal Institute of Technology, Sweden.
    Johansen, K.
    Linköping University, Sweden.
    Robot-forming of prepreg stacks - Development of equipment and methods2016In: ECCM 2016 - Proceeding of the 17th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2016Conference paper (Refereed)
    Abstract [en]

    Within the aerospace industry the manufacturing of composite components with complex shapes, such as spars, ribs and beams are often manufactured using manual layup and forming of prepreg material. Automated processes for prepreg layup and efficient forming techniques like vacuum forming are sometimes difficult to employ to these type of products due to technical limitations. This paper describes the development of tools and the forming sequence needed to automate sequential forming of a complex shape using an industrial robot. Plane prepreg stacks are formed to the final shape using a dual-arm industrial robot equipped with rolling tools. Tests show that the developed tools and the employed sequence can be used to form stacks to the desired shape with acceptable quality.

  • 22.
    Blomdahl, Markus
    RISE, Swerea, SWECAST.
    Rekommendationer för skruvförband med pressgjutgods2005Report (Other academic)
  • 23.
    Bregner, Anders
    RISE, Swerea, IVF.
    Swerea Lättvikt: Tekniska textilier2013Report (Other academic)
  • 24.
    Brouzoulis, J.
    et al.
    Chalmers University of Technology, Sweden.
    Fagerström, M.
    Chalmers University of Technology, Sweden.
    Främby, J.
    Chalmers University of Technology, Sweden.
    Krollmann, J.
    Technische Universität München, Germany.
    Hellström, Peter
    RISE, Swerea, SICOMP.
    Modelling of propagating delaminations in textile reinforced duroplast beams by an enriched shell element formulation2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    Manufacturing and delamination testing, of textile reinforced Duroplast beams, have been performed to determine critical fracture energies in mode I, mode II and mixed mode loading. This includes values for growth initiation as well as propagation. For mode II and mixed mode loading, a large scatter in values were observed and no values corresponding to stable crack growth was obtained. Furthermore, an XFEM enriched shell element, which internally can represent multiple interlaminar cracks, have been used to simulate the DCB test. In the numerical simulation, data from the experimental tests have been used as input for a bilinear cohesive zone model. The load-displacement curve from the FE analysis shows good agreement with the corresponding measured curves, although with a somewhat higher stiffness. 

  • 25.
    Brämming, Mats
    et al.
    RISE, Swerea, MEFOS.
    Björkman, Bo
    Luleå University of Technology, Sweden.
    Samuelsson, Caisa
    Luleå University of Technology, Sweden.
    BOF Process Control and Slopping Prediction Based on Multivariate Data Analysis2016In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, no 3, p. 301-310Article in journal (Refereed)
    Abstract [en]

    In a complex industrial batch processes such as the top-blown BOF steelmaking process, it is a complicated task to monitor and act on the progress of several important control parameters in order to avoid an undesired process event such as "slopping" and to secure a successful batch completion such as a sufficiently low steel phosphorous content. It would, therefore, be of much help to have an automated tool, which simultaneously can interpret a large number of process variables, with the function to warn of any imminent deviation from the normal batch evolution and to predict the batch end result. One way to compute, interpret, and visualize this "batch evolution" is to apply multivariate data analysis (MVDA). At SSAB Europe's steel plant in Luleå, new BOF process control devices are installed with the purpose to investigate the possibility for developing a dynamic system for slopping prediction. A main feature of this system is steelmaking vessel vibration measurements and audiometry to estimate foam height. This paper describes and discusses the usefulness of the MVDA approach for static and dynamic slopping prediction, as well as for end-of-blow phosphorous content prediction. Multivariate data analysis (MVDA) methods have been applied on the top-blown BOF steelmaking process, with the main aim to create industrially applicable static (i.e., prior to blow), as well as dynamic in-blow batch models for predicting the slopping probability. The MVDA approach has also been investigated in regard to in-blow prediction of end-of-blow phosphorous content.

  • 26.
    Carlson, J. E.
    et al.
    Luleå University of Technology, Sweden.
    Lundin, Peter
    RISE, Swerea, KIMAB.
    Measurement of the clamping force applied by load-bearing bolts using a combination of compression and shear ultrasonic waves2015In: 2015 IEEE International Ultrasonics Symposium, IUS 2015, Institute of Electrical and Electronics Engineers Inc. , 2015Conference paper (Refereed)
    Abstract [en]

    Quantitative measurement of the clamping or tightening force of rods and bolts is important when assessing the structural integrity of various constructions. This paper shows that by using a bi-wave ultrasonic pulse-echo technique, it is possible to determine this tightening force without the need of extensive calibration prior to installing the bolts. We show that the ratio of the time-of-flight (TOF) between the transversal and the longitudinal waves changes linearly with the clamping force and that we only need to know the TOF of the unstrained bolt prior to installment. This is then demonstrated experimentally on a 1.1 m rock bolt, using pulses that propagated 6.6 m. Two different methods for estimation of the TOF ratio are evaluated.

  • 27.
    Cedervall, Johan
    et al.
    Uppsala University, Sweden.
    Beran, Premysl
    Nuclear Physics Institute, Czech Republic.
    Vennström, Marie
    AB Sandvik, Sweden.
    Danielsson, Thererse
    Etteplan Sweden AB, Sweden.
    Ronneteg, Sabina
    AB Sandvik, Sweden.
    Höglin, Viktor
    Scienta Sauna Systems AB, Sweden.
    Lindell, David
    RISE, Swerea, KIMAB.
    Eriksson, Olle
    Uppsala University, Sweden.
    André, Gilles
    CEA-Saclay, France.
    Andersson, Yvonne
    Uppsala University, Sweden.
    Nordblad, Per
    Uppsala University, Sweden.
    Sahlberg, Martin
    Uppsala University, Sweden.
    Low temperature magneto-structural transitions in Mn3Ni20P62016In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 237, p. 343-348Article in journal (Refereed)
    Abstract [en]

    X-ray and neutron powder diffraction has been used to determine the crystal and magnetic structure of Mn3Ni20P6. The crystal structure can be described as cubic with space group Fm3¯m (225) without any nuclear phase transformation within studied temperature interval from room temperature down to 4 K. The magnetic structure of Mn3Ni20P6 is complex with two independent magnetic positions for the Mn atoms and the compound passes three successive magnetic phase transitions during cooling. At 30 K the spins of the Mn atoms on the Wyckoff 4a site (Mn1) order to form a primitive cubic antiferromagnetic structure with propagation vector k=(0 0 1). Between 29 and 26 K the Mn atoms on the Wyckoff 8c site (Mn2) order independently on already ordered Mn1 magnetic structure forming a commensurate antiferromagnetic structure with propagation vector k=(0 0 12) and below 26 K, both Mn positions order to form an incommensurate helical structure with propagation vector k=(0 0 ~0.45). Magnetization vs. temperature curve of Mn3Ni20P6 shows a steep increase indicating some magnetic ordering below 230 K and a sharp field dependent anomaly in a narrow temperature range around 30 K.

  • 28.
    Claesson, Erik
    et al.
    RISE, Swerea, KIMAB.
    Rod, Olivier
    RISE, Swerea, KIMAB.
    The effect of alloying elements on the corrosion resistance of brass2016In: Materials Science and Technology, ISSN 0267-0836, E-ISSN 1743-2847, Vol. 32, no 17, p. 1794-1803Article in journal (Refereed)
    Abstract [en]

    A systematic study has been performed on the effect of alloying elements arsenic (As), antimony (Sb) and phosphorus (P) on the dezincification resistance of α-phase in brass. The result showed that P formed particles with Al and Fe already at relatively high temperatures, leaving no P in solid solution and thus no protection against dezincification. Arsenic only formed particles at lower temperatures and offers a satisfactory protecting. However, with increasing As levels grain boundary attack was observed. Samples alloyed with Sb show a satisfactory resistance to dezincification and no grain boundary attack. Finally, a combination of As and Sb at low alloying levels provided an excellent dezincification resistance for brass containing typical impurity levels. This paper is part of a Themed Issue on Brass Alloys. © 2016 Swerea KIMAB.

  • 29.
    Costa, Sergio
    et al.
    RISE, Swerea, SICOMP. Chalmers University of Technology, Sweden.
    Gutkin, Renaud
    RISE, Swerea, SICOMP.
    Olsson, Robin
    RISE, Swerea, SICOMP.
    Finite element implementation of a model for longitudinal compressive damage growth with friction2016In: ECCM 2016 - Proceeding of the 17th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2016Conference paper (Refereed)
    Abstract [en]

    A model for the longitudinal response of laminated fibre-reinforced composites during compressive damage growth is implemented in a Finite Element (FE) package and validated for mesh objectivity. The current work details the FE implementation of the fibre kinking model and in particular challenges associated with mesh objectivity. The numerical way to solve the stress equilibrium and stress compatibility equations simultaneously in an FE framework is also presented. The results show that the current model can be used to predict the kinking response and thus account for the correct energy absorption.

  • 30.
    Dang, B. T. T.
    et al.
    Chalmers University of Technology, Sweden.
    Brelid, H.
    Södra Innovation, Sweden.
    Köhnke, Tobias
    RISE, Swerea, IVF.
    Theliander, H.
    Chalmers University of Technology, Sweden.
    Effect of sodium ion concentration profile during softwood kraft pulping on delignification rate, xylan retention and reactions of hexenuronic acids2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 4, p. 604-611Article in journal (Refereed)
    Abstract [en]

    The objective of this investigation was to study how different concentration profiles of sodium ions influence the delignification rate, hexenuronic acid formation/degradation and xylan retention under kraft cooking conditions. The concentration of sodium ions was varied in time between 0.52 and 3.00 mol/kg solvent, taking two different routes by the controlled addition of sodium carbonate. The reaction rates of hexenuronic acid were found to increase when the sodium ion concentration was at the higher level. Furthermore, the results implied that the kinetics of hexenuronic acid reactions responds rapidly to changes in sodium ion concentration. Delignification and the removal rates of xylan decreased rapidly after the sodium ion concentration was increased. However, when the sodium ion concentration was decreased, the response to the change was delayed. These findings indicate that effects of ionic strength on the rate of delignification and removal of xylan arise as a consequence of changes in solubility and on mass transport phenomena rather than from the rates of chemical reaction. Furthermore, the results suggest that non-dissolved xylan located in the fibre wall matrix may also sorb on cellulose surfaces relatively early on in the cook if the concentration of sodium ions is at high level

  • 31.
    Dang, B. T. T.
    et al.
    Chalmers University of Technology, Sweden.
    Brelid, H.
    Södra Innovation, Sweden.
    Köhnke, Tobias
    RISE, Swerea, IVF.
    Theliander, H.
    Chalmers University of Technology, Sweden.
    Impact of ionic strength on delignification and hemicellulose removal during kraft cooking in a small-scale flow-through reactor2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 3Article in journal (Refereed)
    Abstract [en]

    The effect of ionic strength/sodium ion concentration and type of anions on the delignification rate, the retention of xylan and the reactions of hexenuronic acid during kraft cooking has been investigated. A novel, small, flow-through digester was used in the cooking experiments in order to prevent the resorption of lignin and xylan and to maintain a constant concentration of active chemicals throughout the kraft cook. An increase in ionic strength/sodium ion concentration in the cooking liquor decreases the removal rate of both lignin and xylan during kraft cooking. In general, the removal rate of xylan tends to correlate with the delignification rate. However, the present investigation finds that the retention of xylan at a given degree of delignification increases at high ionic strength/sodium ion concentration. The addition of sodium salts of carbonate or chloride to the cooking liquor was shown to increase the rate of formation/degradation reactions of hexenuronic acids and the total amount of uronic acids substituted on the xylan backbone decreases when the concentration of sodium ions increases in the cooking liquor. This promotes a decrease in the dissolution of xylan and consequently an increase in the retention of xylan in the wood residues. The obtained results demonstrate that the xylan content in the fiber wall increases at higher ionic strength/sodium ion concentration, which leads to a slight increase in pulp yield.

  • 32.
    De Goey, Heleen
    et al.
    RISE, Swerea, IVF. Jönköping University, Sweden.
    Engström, Dan
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Lennartsson, Martin
    Jönköping University, Sweden.
    Linderoth, Henrik
    Jönköping University, Sweden.
    Design Thinking as Facilitator for Sustainable Innovation: Exploring Opportunities at SMEs in the Swedish Wood Products Industry2015In: Proceedings of the 20th International Conference on Sustainable Innovation, 2015Conference paper (Refereed)
    Abstract [en]

    Design thinking (DT) is the application of design practice as an approach to innovate and initiate change. Recently, DT has received increasing attention as an approach to address sustainability challenges. However, this area is less studied. The purpose of this study was to explore how DT could enable small and medium-sized enterprises (SMEs) in the Swedish wood products industry to create more sustainable offers. Various actors from this industry have identified the need to develop sustainable offers, although few discuss how this is realized. Interviews have been conducted with six SMEs to increase understanding on challenges they perceive with developing sustainable products. Current practice is compared to potential benefits of DT described in literature. Three main benefits of DT for SMEs have been identified. It could enable SMEs [1] to redefine the purpose of their offers, [2] to better address needs and [3] to address conflicting requirements regarding sustainability.

  • 33.
    Diószegi, A.
    et al.
    Jönköping University, Sweden.
    Diaconu, V. -L
    Jönköping University, Sweden.
    Fourlakidis, Vasilios
    RISE, Swerea, SWECAST.
    Prediction of volume fraction of primary austenite at solidification of lamellar graphite cast iron using thermal analyses2016In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 124, no 1, p. 215-225Article in journal (Refereed)
    Abstract [en]

    Lamellar graphite cast iron was investigated with carbon equivalents varied between CE = 3.4 and 4.26, cast at various cooling rates between 0.195 and 3.5 °C s-1 covering the limits used for technical applications in the production of complex-shaped lamellar graphite cast iron. Registered cooling curves displaced in two positions in the casting were used to predict the solidification and microstructure formation mechanisms. The predicted volume fraction of primary austenite was compared with the fraction of primary austenite measured on colour micrographs with the help of image analyses. A good correlation has been obtained for medium and slow cooling conditions, while a less good correlation at fast cooling condition was attributed to the used protective environment to preserve thermocouples. The observed fraction and the predicted fraction of primary austenite were in good correlation and followed a consequent variation dependent on the carbon equivalent. Furthermore, the quality of the prediction was dependent on the used numerical algorithm involving cooling information from either one or two thermocouples.

  • 34.
    Diószegi, A.
    et al.
    Jönköping University, Sweden.
    Fourlakidis, Vasilios
    RISE, Swerea, SWECAST.
    Lora, R.
    Jönköping University, Sweden.
    Austenite dendrite morphology in lamellar graphite iron2015In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 28, no 5, p. 310-317Article in journal (Refereed)
    Abstract [en]

    Primary austenite has been underestimated in general when the theories of nucleation, solidification, microstructure formation and mechanical properties were established for cast iron and particularly for lamellar cast iron. The present work aims to investigate the primary austenite morphology of as cast samples of a hypoeutectic lamellar cast iron produced with different cooling rates. Morphological parameters as the area fraction primary austenite, the secondary dendrite arm spacing, the dendrite envelope surface, the coarseness of the primary dendrite expressed as the relation between the volume of the dendrite and its envelope surface and the coarseness of the interdendritic space also known as the hydraulic diameter are measured. Furthermore, the role of the size of the investigation area is revealed to be sequential investigation. A strong relation between all measured morphological parameters and the solidification time has been established, except the volume fraction of primary austenite, which is constant for all cooling conditions. 

  • 35.
    Doroudgarian, N.
    et al.
    Luleå University of Technology, Sweden.
    Pupure, L.
    Luleå University of Technology, Sweden.
    Joffe, Roberts
    RISE, Swerea, SICOMP. Luleå University of Technology, Sweden.
    Moisture uptake and resulting mechanical response of bio-based composites. II. Composites2015In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 36, no 8, p. 1510-1519Article in journal (Refereed)
    Abstract [en]

    The durability of entirely bio-based composites with respect to the exposure to elevated humidity was evaluated. Different combinations of bio-based resins (Tribest, EpoBioX, Envirez) and cellulosic fibers (flax and regenerated cellulose fiber rovings and fabrics) were used to manufacture unidirectional and cross-ply composite laminates. Water absorption experiments were performed at various humidity levels (41%, 70%, and 98%) to measure apparent diffusion coefficient and moisture content at saturation. Effect of chemical treatment (alkali and silane) of fibers as protection against moisture was also studied. However, fiber treatment did not show any significant improvement and in some cases the performance of the composites with treated fibers was lower than those with untreated reinforcement. The comparison of results for neat resins and composites showed that moisture uptake in the studied composites is primarily due to cellulosic reinforcement. Tensile properties of composites as received (RH = 24%) and conditioned (RH = 41%, 70%, and 98%) were measured in order to estimate the influence of humidity on behavior of these materials. Results were compared with data for glass fiber reinforced composite, as a reference material. Previous results from study of unreinforced polymers showed that resins were resistant to moisture uptake. Knowing that moisture sorption is primarily dominated by natural fibers, the results showed that some of the composites with bio-based resins performed very well and have comparable properties with composites of synthetic epoxy, even at elevated humidity. 

  • 36.
    Elger, Ragna
    et al.
    RISE, Swerea, KIMAB.
    Norling, Rikard
    RISE, Swerea, KIMAB.
    Pettersson, R.
    Jernkontoret, Sweden.
    Corrosion and deposit formation on four steels exposed in the syngas section after a biomass gasifier2016In: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 67, no 9, p. 939-951Article in journal (Refereed)
    Abstract [en]

    In this work, three different stainless steels (304L (CrNi-18-8), 253 MA®(CrNiSi-21-11), Kanthal® A-1 (FeCrAl)) and a reference low-alloyed ferritic steel (16Mo3 (Fe0.3Mo)) were exposed in a commercial biomass gasifier for three periods of 9 min, 580 and 1054 h in the temperature range 350–500 °C. Biomass is a fuel with generally higher amounts of chlorine and lower amounts of sulphur compared to coal and there is a current lack of data on materials performance in such environments. A high level of zinc sulphide was observed on the surfaces of all materials after exposure. It is argued that zinc plays a key role in capturing sulphur in this environment, thus preventing iron from sulphidation. Some incorporation of sulphur in the oxide scale was observed for Fe0.3Mo and CrNi-18-8. CrNiSi-21-11 showed some internal oxidation and pitting was observed for the FeCrAl material. All four materials showed acceptable performance with low total metal loss.

  • 37.
    Elger, Ragna
    et al.
    RISE, Swerea, KIMAB.
    Viklund, Peter
    DEKRA Industrial AB, Sweden.
    Pettersson, Rachel
    Jernkontoret, Sweden.
    Laboratory testing to evaluate candidate alloys for superheaters in waste-fired boilers2016In: Materials at High Temperature, ISSN 0960-3409, E-ISSN 1878-6413, Vol. 33, no 6, p. 587-595Article in journal (Refereed)
    Abstract [en]

    Two types of laboratory tests were used to evaluate the behaviour of a wide range of steels in chlorinating–sulphidising conditions: high temperature exposure after applying salt by dipping in an aqueous KCl/ZnCl2 solution and salt-bed test in a ZnCl2/NaCl/KCl/CaSO4 salt mixture. The exposures were performed at 500 °C in a gas comprising N2/HCl/SO2/O2/N2. For the alloy group with 20–30 wt-% chromium and 25–65 wt-% nickel, the extrapolated metal loss was below 0.2 mm/year in the salt dip, up to 6 mm/year in the salt-bed test with 10% Cl and up to 20 mm/year in the 20% Cl salt-bed test. The intermediate alloy group showed poorer performance in the salt-bed; Esshete1250 showed also large spallation in the salt dip test. Results were compared with plant-exposed samples. Further refinement of the salt dip test is suggested for material ranking in the superheater region of a waste or biomass-fired incinerator. © 2016 Swerea Kimab.

  • 38.
    Fahlkrans, Johan
    et al.
    RISE, Swerea, KIMAB.
    Melander, Arne
    RISE, Swerea, KIMAB. KTH Royal Institute of Technology, Sweden.
    Gardstam, Johannes
    RISE, Swerea, KIMAB.
    Haglund, Sven
    RISE, Swerea, KIMAB.
    Straightening of induction hardened shats-inluence on fatigue strength and residual stress2012In: HTM - Haerterei-Technische Mitteilungen, ISSN 0341-101X, Vol. 67, no 3, p. 179-187Article in journal (Refereed)
    Abstract [en]

    Straightening of distorted components ater heat treatment is oten a necessary operation. he straightening operation leads to local plastic deformation, which is afecting the residual stress state, the hardness, and ultimately the fatigue strength of the component. he present study evaluates the inluence of a straightening operation on fatigue strength and on the residual stress state of induction hardened shats of steel EN 42CrMo4. A simpliied FEM model was formulated. he model showed that the residual stress state was asymmetric along the circumference of a straightened shat. Fatigue testing was performed in a three point bending and showed that the fatigue strength was reduced by up to some 20 % by heavy straightening. A fracture mechanics model for fatigue crack growth and arrest was developed. he model could be used to predict the fatigue strength of a straightened shat provided that the residual stress state was known. 

  • 39.
    Fahlström, Karl
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB. RISE, Swerea, KIMAB.
    Andersson, Oscar
    Volvo Cars, Sweden.
    Todal, Urban
    Volvo Cars, Sweden.
    Melander, Arne
    RISE, Swerea, KIMAB.
    Minimization of distortions during laser welding of ultra high strength steel2015In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 27, no S2, article id S29011Article in journal (Refereed)
    Abstract [en]

    Ultra high strength steels are frequently used within the automotive industry for several components. Welding of these components is traditionally done by resistance spot welding, but to get further productivity and increased strength, laser welding has been introduced in the past decades. Fusion welding is known to cause distortions due to built in stresses in the material. The distortions result in geometrical issues during assembly which become the origin of low joint quality due to gaps and misfits. U-beam structures of boron steel simulating B-pillars have been welded with laser along the flanges. Welding parameters and clamping have been varied to create different welding sequences and heat input generating a range of distortion levels. The distortions have been recorded dynamically with an optical measurement system during welding. In addition, final distortions have been measured by a digital Vernier caliper. The combined measurements give the possibility to evaluate development, occurrence, and magnitude of distortions with high accuracy. Furthermore, section cuts have been analyzed to assess joint geometry and metallurgy. The results show that final distortions appear in the range of 0-8 mm. Distortions occur mainly transversely and vertically along the profile. Variations in heat input show clear correlation with the magnitude of distortions and level of joint quality. A higher heat input in general generates a higher level of distortion with the same clamping conditions. Section cuts show that weld width and penetration are significantly affected by welding heat input. The present study identifies parameters which significantly influence the magnitude and distribution of distortions. Also, effective measures to minimize distortions and maintain or improve joint quality have been proposed. Finally, transient finite element (FE) simulations have been presented which show the behavior of the profiles during the welding and unclamping process. 

  • 40.
    Fahlström, Karl
    et al.
    RISE, Swerea, KIMAB. RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Persson, Kjell Arne
    RISE, Swerea, KIMAB.
    Larsson, Johnny
    Volvo Cars, Sweden.
    Vila Ferrer, Elisenda
    Gestamp, Spain.
    Evaluation of laser weldability of 1800 and 1900 MPa boron steels2016In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 28, no 2, article id 022426Article in journal (Refereed)
    Abstract [en]

    Ultrahigh strength steels are frequently used within the automotive industry. The driving force for use of these materials is to exchange thicker gauges to thinner and lighter structures. To get excellent strength and beneficial crash performance, the steel is microalloyed with boron which contributes to the 1500 MPa tensile strength. Increasing the carbon content will give superior tensile strength up to 2000 MPa. Welding of these components is traditionally done by resistance spot welding, but to get further productivity and increased stiffness of the structure, laser welding can be introduced. Welding of boron alloyed high strength steel is in general a stable and controlled process, but if increasing the carbon content quality issues such as cracking could possibly be a problem. In the present study, weldability of two different hardened boron steels with tensile strengths of 1800 and 1900 MPa, respectively, has been evaluated. Laser welding has been done in a lap joint configuration with 3.8-4.7 kW and varying welding speed between 3.5 and 5.5 m/min. As reference, results from more conventional 1500 MPa boron steel have been compared to 1800 and 1900 MPa boron steels to show the influence of the carbon content. Metallographic investigation, hot crack test, cold crack test, shear tensile, and cross-tension strength tests have been done. The results show that a weld quality similar to that for conventional boron steel can be achieved. Cracking and other defects can be avoided. As expected when welding martensitic steels, the failure mode in tensile testing is brittle. No weld defects have been found that influence strength. The sheet interface weld width, which together with stack-up thickness correlates with strength of the joint, could be increased by increasing the heat input and defocusing the laser beam. The effect of increased carbon content on weldability will be discussed more in detail, as well as the risk of cracking.

  • 41.
    Fasth Berglund, Åsa
    et al.
    Chalmers Tekniska Högskola.
    Harlin, Ulrika
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers Tekniska Högskola.
    Mattsson, Sandra
    RISE, Swerea, IVF. Chalmers Tekniska Högskola.
    Groth, Cecilia
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Åkerman, Magnus
    Chalmers Tekniska Högskola.
    Gullander, Per
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Creatinga structured MEETing arena for knowledge-sharing2014Conference paper (Other academic)
    Abstract [en]

    This paper aims to describe how to create and structure a meeting arena bycombining organisation structure and information structure; this will be used in orderto create an innovative and creative arena for knowledge sharing and problemsolving within the company. The model is exemplified by four industrial casestudies.Results reveal that most of the companies do not have any standards forinformation- or knowledge sharing, most improvement potentials are seen instructuring and storing the right information (IS), aiming from tacit towards explicitknowledge (OS) and this could be done by structuring the questions in the OS-M-ISmodel and by creating innovative and creative meeting arenas.

  • 42.
    Fernberg, Patrik
    RISE, Swerea, SICOMP. Luleå University of Technology, Sweden.
    Fibre reinforced polyimide composites and structures manufactured with resin transfer moulding - Overview of procedures and properties2016In: ECCM 2016 - Proceeding of the 17th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2016Conference paper (Refereed)
    Abstract [en]

    In this paper, the major outcomes from a recently completed research program with ambition to develop polyimide carbon fibre composites with temperature ability above 360°C are reported. Data from characterisation of the processing properties such as viscosity and cure behaviour are presented alongside with data on the mechanical properties at room temperature of quasi-isotropic composites based on the developed resin and 8-harness satin weave carbon fibre fabrics. The paper also contains a demonstration of the use the material system in a demonstrator component.

  • 43.
    Fernberg, Patrik
    et al.
    RISE, Swerea, SICOMP. Luleå University of Technology, Sweden.
    Joffe, Roberts
    RISE, Swerea, SICOMP. Luleå University of Technology, Sweden.
    Tsampas, Spyros
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP.
    Mannberg, Peter
    RISE, Swerea, SICOMP.
    Influence of post-cure on carbon fibre polyimide composites with glass transition temperatures above 400c2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    The current communication present results from work on polymeric composites with extreme temperature performance. This study focuses on carbon fibre composites based on a new phenyl ethynyl terminated polyimide formulation NEXIMID® MHT-R (Nexam Chemicals AB, Sweden) based on hexafluoroisopropylidene bisphthalic dianhydride (6-FDA), 4-(Phenylethynyl)Phthalic Anhydride (4-PEPA) and ethynyl bis-phthalic anhydride (EBPA). In particular influence of post-cure conditions such as time, temperature and atmosphere on Tg of the composites is investigated. In addition to this monitoring and analyses of the consequences of post-cure on mass loss and occurrence of micro-cracks is carried out. Three different post-curing temperatures are considered in this study: 400°C, 420°C and 440°C. Two different atmospheres, air and inert by nitrogen, were also investigated. In summary the results reveal that remarkably high Tg, up to around 460°C, is achieved with only very limited mass loss. It was also observed that some, but limited amounts of, micro-cracks are developed within the laminates due to the inevitable high thermal stresses generated upon cooling from cure temperature.

  • 44.
    Fourlakidis, Vasilios
    RISE, Swerea, SWECAST.
    A study on ductile iron production without the use of feeders2013In: Foundry Trade Journal International, ISSN 1758-9789, Vol. 187, no 3702, p. 60-62Article in journal (Refereed)
    Abstract [en]

    This paper investigates the effects of graphite added as a conditioner, of lanthanum containing nodulariser and of pouring temperature on the formation of shrinkage porosity in ductile iron casting with a eutectic composition. In this experiment for each heat the cooling curves were recorded by the use of Quick-Cups (thermal analysis cups) and different solidification parameters such as TElow, GRF1, GRF2 and TS were calculated and compared with the porosity which was found from the microstructure examination. The results show that there is a good correlation between the amount of the shrinkage formation and the thermal analysis values. Also this experiment confirms that by using certain treating elements and pouring temperature which was between 1340-1350°C it is possible to eliminate the shrinkage defects in ductile iron castings without using feeders.

  • 45.
    Frisk, Karin
    et al.
    RISE, Swerea, KIMAB.
    Borggren, Ulrika
    SSAB, Sweden.
    Precipitation in Microalloyed Steel by Model Alloy Experiments and Thermodynamic Calculations2016In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 47, no 10, p. 4806-4817Article in journal (Refereed)
    Abstract [en]

    Precipitation in microalloyed steel has been studied by applying thermodynamic calculations based on a description of the Gibbs energies of the individual phases over the full multicomponent composition range. To validate and improve the thermodynamic description, new experimental investigations of the phase separation in the cubic carbides/nitrides/carbonitrides in alloys containing Nb, V, Mo, and Cr, have been performed. Model alloys were designed to obtain equilibrium carbides/carbonitrides that are sufficiently large for measurements of compositions, making it possible to study the partitioning of the elements into different precipitates, showing distinctly different composition sets. The reliability of the calculations, when applied to multicomponent alloys, was tested by comparing with published experimental studies of precipitation in microalloyed steel. It is shown that thermodynamic calculations accurately describe the observed precipitation sequences. Further, they can reproduce several important features of precipitation processes in microalloyed steel such as the partitioning of Mo between matrix and precipitates and the variation of precipitate compositions depending on precipitation temperature. 

  • 46.
    Frisk, Karin
    et al.
    RISE, Swerea, KIMAB.
    Magnusson, Hans
    RISE, Swerea, KIMAB.
    Chasoglou, D.
    Höganäs AB, Sweden.
    Bergman, O.
    Höganäs AB, Sweden.
    Studies of oxide reduction during sintering of Cr alloyed PM steel by coupled experimental and diffusion simulations2016In: World PM 2016 Congress and Exhibition, European Powder Metallurgy Association (EPMA) , 2016Conference paper (Refereed)
    Abstract [en]

    Oxide reduction in Cr alloyed PM steel has been simulated experimentally by measuring the oxygen loss from powders when exposed to a heating cycle, by photo acoustic spectroscopy (PAS) and by thermogravimetric analysis (TGA). Pressed samples were heated in dry hydrogen gas using a defined, slow, heating rate up to 1300oC. The oxides in the powder are reduced by the hydrogen gas. From the PAS curves distinct reduction temperatures are observed, that can be correlated to the type of oxide by comparing with thermodynamic calculations of the oxide stabilities. The experimental results were analyzed by diffusion simulations that involve a description of the diffusion controlled oxide reduction. It is shown how the calculated rate of oxygen diffusion in the samples, compared with the experimental results, has been applied as a tool for increased understanding of the reduction during sintering.

  • 47.
    Frisk, Karin
    et al.
    RISE, Swerea, KIMAB.
    Rännar, L. -E
    Mid Sweden University, Sweden.
    Koptyug, A.
    Mid Sweden University, Sweden.
    Petterson, Niklas
    RISE, Swerea, KIMAB.
    Persson, Daniel
    RISE, Swerea, KIMAB.
    Leicht, A.
    Chalmers University of Technology, Sweden.
    Sundaram, M. V.
    Chalmers University of Technology, Sweden.
    Hryha, E.
    Chalmers University of Technology, Sweden.
    Nyborg, L.
    Chalmers University of Technology, Sweden.
    Ahlfors, M.
    Quintus Technologies, Sweden.
    Characterisation of EBM-built shelled samples of Ti6Al4V compacted by HIP2016In: World PM 2016 Congress and Exhibition, European Powder Metallurgy Association (EPMA) , 2016Conference paper (Refereed)
    Abstract [en]

    Compaction of additively manufactured Ti6Al4V components by Hot Isostatic Pressing (HIP) is often applied to eliminate porosity, producing fully dense material. In the present work shelled samples produced by Electron Beam Melting with the Arcam process (EBM) were compacted by HIP to produce fully dense samples. Cylindrical samples were studied. The walls of the cylinders were built with EBM, and the powder from the process was left uncompacted inside the cylinders. Samples with different wall thicknesses were produced. The samples were thereafter subjected to a HIP compaction. The critical wall thicknesses needed for compaction were evaluated, and the microstructures characterized. The results show that fully dense samples, with very fine microstructures, are possible.

  • 48.
    Fuertes, Nuria
    et al.
    RISE, Swerea, KIMAB.
    Pettersson, R.
    Jernkontoret, Sweden.
    Review-passive film properties and electrochemical response of different phases in a Cu-alloyed stainless steel after long term heat treatment2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 7, p. C377-C385Article in journal (Refereed)
    Abstract [en]

    In this work the influence of copper (0-4 wt%) on the microstructure, passive film properties and local electrochemical response of 25Cr7Ni-type duplex stainless steel is investigated after long term heat-treatment at 800◦C for 6 months. This heat-treatment was done to promote the formation of different phases which could be studied in terms of passive film properties and electrochemical response. The unique microstructures of the alloys comprise austenite, sigma phase, Cr2N nitrides and, for the 2 wt% and 4 wt% Cu alloys, epsilon-Cu phase. The results show that alloying with Cu increases slightly the amount of isothermal Cr2N nitrides and epsilon-Cu phase, but decreases the sigma phase fraction. The location of pitting corrosion as well as the Electrochemical Potential (EP), or electron work function, measured with Scanning Kelvin Probe Force Microscopy (SKPFM) show that the epsilon-Cu phase has the lowest corrosion resistance. The EP appears to depend more on the composition of the underlying phase than on the thickness of the passive film. Cr-nitrides have the highest EP followed by sigma phase, austenite and epsilon-Cu phase. There is a clear decrease of EP of the austenitic phase when 2 wt% Cu is added in the alloy. 

  • 49.
    Færevik, H.
    et al.
    SINTEF, Norway.
    Gersching, D.
    TITK, Germany.
    Hagström, Bror
    RISE, Swerea, IVF.
    Novel temperature regulating fibers and garments2013In: Chemical Fibers International, ISSN 1434-3584, Vol. 63, no 2, p. 89-90Article in journal (Refereed)
    Abstract [en]

    The objective of the EU-funded research project Noterefiga was to develop novel temperature regulating fibers and innovative textile products for thermal management and improved comfort. The temperature regulating effect was achieved by novel methods of incorporating large amounts of phase changing materials (PCM) in textile fibers. The PCM melted and absorbed the heat from the body in the form of latent heat when the body temperature increased. The PCM crystallized and the stored heat was released again when the temperature dropped. It was assumed that clothes with built-in thermo-regulating properties would provide maintained thermal comfort in difficult thermal environments and physical activity situations. The thermophysiological effect of the developed PCM garments were evaluated on 24 human subjects in controlled environmental conditions under the Noterefiga project.

  • 50.
    Ghasemi, Rohollah
    et al.
    Jönköping University, Sweden.
    Elmquist, Lennart
    Jönköping University, Sweden.
    Svensson, Henrik
    RISE, Swerea, SWECAST.
    König, Mathias
    Scania AB, Sweden.
    Jarfors, Anders Eric Wollmar
    Jönköping University, Sweden.
    Mechanical properties of Solid Solution-Strengthened CGI2016In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 1-2, p. 98-105Article in journal (Refereed)
    Abstract [en]

    Despite the increased usage of pearlitic compacted graphite iron (CGI) in heavy vehicle engines, poor machinability of this material remains as one of the main technical challenges as compared to conventional lamellar iron. To minimise the machining cost, it is believed that solution-strengthened CGI material with a ferritic matrix could bring an advantage. The present study focuses on the effect of solution strengthening of silicon and section thickness on tensile, microstructure and hardness properties of high-Si CGI materials. To do so, plates with thicknesses from 7 to 75 mm were cast with three different target silicon levels 3.7, 4.0 and 4.5 wt%. For all Si levels, the microstructure was ferritic with a very limited pearlite content. The highest nodularity was observed in 7 and 15 mm plate sections, respectively, however, it decreased as the plate thickness increased. Moreover, increasing Si content to 4.5 wt% resulted in substantial improvement up to 65 and 50% in proof stress and tensile strength, respectively, as compared to pearlitic CGI. However, adding up Si content to such a high level remarkably deteriorated elongation to failure. For each Si level, results showed that the Young’s modulus and tensile strength are fairly independent of the plate thickness (30–75 mm), however, a significant increase was observed for thin section plates, particularly 7 mm plate due to the higher nodularity in these sections. 

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