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  • 51.
    Ali, Sharafat
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Paul, Biplab
    Linköping University, Sweden.
    Magnusson, Roger
    Linköping University, Sweden.
    Erik, Ekström
    Linköping University, Sweden.
    Pallier, Camille
    Linköping University, Sweden.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Eklund, Per
    Linköping University, Sweden.
    Birch, Jens
    Linköping University, Sweden.
    Optical and mechanical properties of amorphous Mg-Si-O-N thin films deposited by reactive magnetron sputtering2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 372, no 25, p. 9-15Article in journal (Refereed)
    Abstract [en]

    In this work, amorphous thin films in Mg-Si-O-N system typically containing >15 at.% Mg and 35 at.% N were prepared in order to investigate especially the dependence of optical and mechanical properties on Mg composition. Reactive RF magnetron co-sputtering from magnesium and silicon targets were used for the deposition of Mg-Si-O-N thin films. Films were deposited on float glass, silica wafers and sapphire substrates in an Ar, N2 and O2 gas mixture. X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, spectroscopic ellipsometry, and nanoindentation were employed to characterize the composition, surface morphology, and properties of the films. The films consist of N and Mg contents up to 40 at.% and 28 at.%, respectively and have good adhesion to substrates and are chemically inert. The thickness and roughness of the films increased with increasing content of Mg. Both hardness (16–21 GPa) and reduced elastic modulus (120–176 GPa) are strongly correlated with the amount of Mg content. The refractive index up to 2.01 and extinction coefficient up to 0.18 were found to increase with Mg content. The optical band gap (3.1–4.3) decreases with increasing the Mg content. Thin film deposited at substrate temperature of 100 °C shows a lower value of hardness (10 GPa), refractive index (1.75), and higher values of reduced elastic modulus (124 GPa) as compared to the thin film deposited at 310 °C and 510 °C respectively, under identical synthesis parameters.

  • 52.
    Ali, Sharafat
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Paul, Biplab
    Linköping University, Sweden.
    Magnusson, Roger
    Linköping University, Sweden.
    Greczynski, Grzegorz
    Linköping University, Sweden.
    Broitman, Esteban
    Linköping University, Sweden.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Eklund, Per
    Linköping University, Sweden.
    Birch, Jens
    Linköping University, Sweden.
    Thin films in M-Si-O-N thin systems2017In: 44th International Conference on Metallurgical Coating and Thin Films (ICMCTF), San Diego, CA, USA, 24-28 Apr 2017, 2017Conference paper (Refereed)
  • 53.
    Ali, Sharafat
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Paul, Biplab
    Magnusson, Roger
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Eklund, Per
    Birch, Jens
    Study of SiN, SiON and Mg-Si-O-N thin films by spec-troscopic elipsometry2016In: Optics and photonics conference, 2-3 November, 2016, Linköping, Sweden, 2016Conference paper (Refereed)
  • 54.
    Ali, Sharafat
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Wójcik, Natalia A.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gdańsk University of Technology, Poland.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Kamitsos, Efstratios
    Theoretical and Physical Chemistry Institute, Greece.
    Li, Xinghua
    Corning Incorporated, USA.
    Luo, Jian
    Corning Incorporated, USA.
    Möncke, Doris
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Alfred University, USA;.
    Synthesis, structural characterization, and thermal properties of Ca- and La-doped soda-lime glasses by laser melting2020In: International Journal of Applied Glass Science, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Laser melting techniques have been used in the preparation of unconventional glasscompositions with high melting temperatures. Thus, we wanted to test the feasibilityof using a CO2 laser in the preparation of nitrogen-rich oxynitride glasses and nitridesilicate glasses. Melting from oxides and metallic raw materials, we wanted to studyfirst glass formation and possible evaporation losses of the glass components. Twoglass series were prepared and studied for their structure and thermal properties, onewith Ca2+- and a higher melting La3+-doped soda-lime-silicate (SLS) series. In lessthan 3 minutes of laser melting, spheres of up to 6 mm diameter were successfullyfabricated. The obtained glass samples were homogeneous and transparent in thevisible region. X-ray diffraction and Raman spectroscopic analysis confirmed theamorphous nature of the synthesized samples. Sodium losses increase as calcium isadded to the soda-lime-silicate glass. As expected, increasing Ca2+ or La3+ additionlead to increased depolymerization of the silicate network. Moreover, the increasesin Tg with the addition of Ca2+ or La3+ ions indicating strengthening of the sodalime-silicate glass by increasing strength of the M-O bonds of divalent and trivalentions over monovalent sodium ions, weak Na-O bonds also resulting in significantevaporation loss during the short laser melting times. The thermal stability decreasesupon addition of Ca2+ or La3+ ions to the soda-lime-silicate glasses.

  • 55.
    Almaari, Firas
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Aljbban, Essam
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Strain Rate Effect on Fracture Mechanical Properties of Ferritic-Pearlitic Ductile Iron.2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study investigates the effect of strain rate on fracture properties of Ferritic-Pearlitic Ductile Iron.

    A series of dynamic three point bending tests, with various load application rates, are conducted on Charpy V-notch specimens, in room temperature and approximately -18 °C.

    The tests are performed in a custom-made fixture and during the tests, force and displacement data are recorded. A XFEM (Extended Finite Element Method) model of the test setup has been established and material data from the tests are used as input to the model.

    The test results show a strong dependency of the strain rate regarding the force needed for crack initiation. Moreover, it can be concluded that low temperature makes the material very brittle, even at low load application rates.

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  • 56.
    Altgen, Michael
    et al.
    Aalto Univ, Finland.
    Willems, Wim
    FirmoLin Technol BV, Netherlands.
    Hosseinpourpia, Reza
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Rautkari, Lauri
    Aalto Univ, Finland.
    Hydroxyl accessibility and dimensional changes of Scots pine sapwood affected by alterations in the cell wall ultrastructure during heattreatment2018In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 152, p. 244-252Article in journal (Refereed)
    Abstract [en]

    There is a complex link between the water sorption behavior and the presence of accessible hydroxyl groups in the wood cell wall, which can be altered by heat-treatment (HT). This study analyses the effect of changes in the cell wall ultrastructure caused by two HT techniques on the hydroxyl accessibility, water vapor sorption and dimensional changes of Scots pine (Pinus sylvestris L.) sapwood. HT of wood in pressurized hot water at 120-170 °C was applied to cause the preferential bond cleavage, whereas HT of wood in oven-dry state in superheated steam at 180-240 °C was performed to create additional covalent cross-links within the cell wall matrix. Removal of cell wall polymers by HT and water leaching reduced the oven-dry dimensions of wood and enhanced the cellulose aggregation during drying. Cellulose aggregation restricted the cell wall shrinkage in circumferential direction, resulting in inhomogeneous shrinkage of the cell wall with only little changes in lumen volume by HT. Cellulose aggregation also reduced the water-saturated dimensions, but a decrease in swelling was only achieved when additional cross-links were formed by HT in dry state. Additional cross-links in the cell wall matrix also resulted in an additional reduction in water sorption at 25 °C and 93% RH. However, this was not caused by a further reduction in the hydroxyl accessibility. Instead, cross-linking was shown to reduce the amount of accessible OH groups that are simultaneously active in sorption, which was explained based on the concept of sorption of water dimers at hydroxyl group pairs at high RH levels.

  • 57.
    Attila, Dioszegi
    et al.
    Jönköping University, Dept of Mechanical Engineering/Component Technology.
    Elmquist, Lennart
    Jönköping University, Dept of Mechanical Engineering/Component Technology.
    Orlenius, Jessica
    Jönköping University, Dept of Mechanical Engineering/Component Technology.
    Dugic, Izudin
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Defect Formation of Grey Cast Iron2009Conference paper (Refereed)
    Abstract [en]

    Cast iron is one of the oldest technical alloys used for creating objects. Foundrymen from the very beginning ofcasting was fighting to avoid casting defects. In the beginning a successfully performed casting was associated withwitchcraft. Cast component producers suffer yearly substantial expanses due to rejecting or repairing castings. Thepresent work will summarize research efforts to understand formation mechanisms of defects, performed incollaboration with Swedish foundries during the last years. The presented work will focus on defects, specific castingof gray iron components. Studied defects are gas porosity, shrinkage porosity and metal expansion penetration.Novell experimental set up has been developed or existing methods has been improved to study defect formationmechanisms. Today we can realize that casting without defects are possible only by approaching the defect formationmechanism with multidisciplinary science.

  • 58.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Mechanical properties of sound and of deteriorated softwood at different length scales: Poromicromechanical modeling and experimental investigations2011Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Due to its natural origin and its inherent heterogeneities, mechanical properties of wood are highly anisotropic and show a broad variability, not only between different wood species, but also within a tree. Similar to other biological materials, the wood mi- crostructure is well organized and hierarchically structured from the annual rings visible to the naked eye down to the wood polymers cellulose, hemicellulose, and lignin at the nanometer-scale. This thesis aims at a deeper understanding of the role of different hi- erarchical levels and their corresponding physical and chemical characteristics in relation to mechanical properties of sound wood and of deteriorated wood. This is achieved by means of micromechanical modeling and experimental analyses.

    This thesis starts with the re-formulation of an existing micromechanical model for the elastic behavior and elastic limit states of wood in the framework of poromechanics. The mechanical role of cell wall water at different hierarchical levels is investigated by means of this model. In a broader sense, the developed model allows to investigate the transition of eigenstresses from the cell wall to the softwood level. Moreover, this poromicromechanical model forms the basis for subsequent consideration of a microscopic failure criterion for lignin for the derivation of softwood failure stresses. The suitability of the modeling approach is underlined by a satisfactory agreement of the model-predicted failure stresses with experimental results of biaxial strength tests on Norway spruce.

    As a result of partly considerably different microstructural characteristics, Common yew exhibits exceptional mechanical properties compared to other softwood species. The re- lationship between microstructure and stiffness properties of Common yew and Norway spruce is investigated by means of the poromicromechanical model and mechanical tests across various length scales. Moreover, this offers the opportunity of a broader model validation. The influence of differences in microfibril angle of the S2 cell wall layer and in mass density between yew and spruce is found to be more dominant than the influence of differences in the annual ring characteristics.

    The suitability of the poromicromechanical model to predict changes in mechanical prop- erties upon fungal decay is demonstrated. For this purpose, relationships between mi- crostructure and mechanical properties of deteriorated wood are experimentally explored. Changes in mechanical properties and in the microstructure, measured at pine wood samples after standard wood durability tests using one brown rot fungus (Gloeophyl- lum trabeum) and one white rot fungus (Trametes versicolor), are presented. Transverse stiffnesses are revealed to be more sensitive to degradation than longitudinal stiffness, particularly as a result of pronounced degradation of hemicelluloses. Moreover, ultrason- ically derived anisotropy ratios of elastic stiffnesses allow to identify certain degradation mechanisms of the two considered fungi. The experimental campaign is complemented by micromechanical modeling. For this purpose, the micromechanical model is extended to take into account degradation-specific microstructural characteristics. 

  • 59. Bader, Thomas K.
    et al.
    Braovac, Susan
    Fackler, Karin
    Hofstetter, Karin
    Stiffness Properties of the Archaeological Oak Wood from the Oseberg Ship2011In: Cultural Heritage Preservation.EWCHP - 2011: Proceedings of the European Workshop on Cultural Heritage Preservation. Berlin, Germany, September 26 to 28, 2011, Fraunhofer IRB Verlag, 2011, p. 164-170Conference paper (Refereed)
  • 60.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Braovac, Susan
    University of Oslo, Norway.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Microstructure-Stiffness Relations of the Ancient Oak Wood from the Oseberg Ship2010In: International Workshop on "Modeling Mechanical Behavior of Wooden Cultural Objects", Krakow, 2010, p. 22-23Conference paper (Other academic)
  • 61.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Dastoorian, Foroogh
    Vienna University of Technology, Austria ; University of Tehran, Iran.
    Ebrahimi, Ghanbar
    University of Tehran, Iran.
    Unger, Gerhard
    Vienna University of Technology, Austria.
    Lahayne, Olaf
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Pichler, Bernhard
    Vienna University of Technology, Austria.
    Combined ultrasonic-mechanical characterization of orthotropic elastic properties of an unrefined bagasse fiber-polypropylene composite2016In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 95, p. 96-104Article in journal (Refereed)
    Abstract [en]

    Use of wood-fiber plastics for construction purposes calls for comprehensive understanding of their anisotropic mechanical properties. As a respective contribution, we here report the first-ever complete elasticity characterization of an orthotropic bagasse fiber polypropylene composite, requiring identification of nine independent constants. For this purpose, we carry out characterization in principal material directions. Six diagonal stiffness tensor components are quantified based on ultrasonic longitudinal and shear wave velocity measurements; and three diagonal compliance tensor components are identified as the inverses of three Young’s moduli derived from unloading regimes of quasi-static uniaxial compression tests. Combination of all measurement data in the framework of orthotropic linear elasticity provides access to all off-diagonal stiffness and compliance tensor components, opening the door to quantifying six Poisson’s ratios. 

  • 62.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Poroelastic properties of hardwood at different length scales2013In: Poromechanics V: proceedings of the fifth Biot Conference on Poromechanics, July 10-12, 2013, Vienna, Austria / [ed] Christian Hellmich, Bernhard Pichler, Dietmar Adam, Reston: American Society of Civil Engineers (ASCE), 2013, p. 1830-1836Conference paper (Other academic)
    Abstract [en]

    Hardwoods show a very complex, hierarchically organized microstructure. Slight structural differences at various length scales bring about a huge variety of hardwood species. This motivates the development of a micromechanical model for hardwood. Since differences in the microstructure of the material can be considered in the model, it offers the opportunity to explain the variability of mechanical properties of the whole class of hardwood. The micromechanical model is formulated in the framework of poroelasticity. In this contribution, poroelastic properties at different length scales of the material are discussed. Validation of the micromechanical model is based on an extensive experimental database covering elastic properties and microstructural characteristics of different temperate and tropical hardwood species. Exemplary parameter studies demonstrate the ability of the model to study the contribution of specific microstructural characteristics to the load transfer and the deformation characteristics of wood. 

  • 63.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Micromechanical modeling of Common yew and Norway spruce2013In: Proceedings in Applied Mathematics and Mechanics: PAMM, ISSN 1617-7061, E-ISSN 1617-7061, Vol. 13, no 1, p. 185-186Article in journal (Refereed)
    Abstract [en]

    In this contribution, a micromechanical modeling approach in the framework of poromechanics is adopted to study structure-stiffness relations of two quite different species, namely spruce and yew, in detail. In particular, microstructural specialties of yew and spruce are assessed. A dominant influence of the cellulose content and its orientation on the stiffness of the cell wall is revealed, while on the macroscopic scale, density is found to be the governing microstructural characteristic for elastic properties.

  • 64.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Micromechanical Modeling of Wood: Multiscale Modeling and Model Validation2013Conference paper (Other academic)
    Abstract [en]

    Due to its natural origin and its inherent heterogeneities, mechanical properties of wood are highlyanisotropic and show a broad variability, not only between different wood species, but also within a tree [1].Similar to other biological materials, the wood microstructure is well organized and hierarchically structuredfrom the annual rings visible to the naked eye down to the wood polymers cellulose, hemicellulose, andlignin at the nanometer-scale. The aim of the research conducted at the Institute for Mechanics of Materialsand Structures is a deeper understanding of the role of different hierarchical levels and their correspondingphysical and chemical characteristics in relation to mechanical properties of softwood and hardwood. This isachieved by means of micromechanical modeling and experimental analyses at various length scales.

    A micromechanical model provides the opportunity to predict poroelastic properties of softwood andhardwood tissues at different hierarchical levels from microstructural and compositional data [1,2]. Thehierarchical organization of wood is mathematically represented in a multiscale model. Effective poroelasticproperties are predicted by means of continuum micromechanical approaches (self-consistent method andMori-Tanaka method), the unit cell method, and laminate theory. These approaches are extended to accountfor water-induced eigenstresses within representative volume elements and repetitive unit cells, which aresubsequently upscaled to the macroscopic wood level.

    Verification of the micromechanical model for softwood and hardwood with a comprehensive experimentaldataset, shows that it suitably predicts elastic properties at different length scales under the assumption ofundrained conditions [3,4]. Moreover, Biot tensors, expressing how much of the cell wall water-induced porepressure is transferred to the boundary of an overall deformation-free representative volume element (RVE),and Biot moduli, expressing the porosity changes invoked by a pore pressure within such an RVE can bestudied at different length scales. Consequently, the relevance and the contribution of specificmicrostructural characteristics to the load transfer and the deformation characteristics in case of moisturechanges in wood can be studied. Besides the scientific interest in structure-function-relationships, theseinvestigations are motivated by the growing importance of wood as building material.

  • 65.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Shear stiffness and its relation to the microstructure of 10 European and tropical hardwood species2017In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 2, p. 82-91Article in journal (Refereed)
    Abstract [en]

    In this study, shear stiffness properties of 10 different hardwood species and their relation to the corresponding species-specific microstructure are investigated. For this purpose, shear stiffness of 10 different hardwood species is experimentally measured by means of ultrasonic testing. In addition, a micromechanical model for hardwood is applied in order to illustrate the influence of certain microstructural characteristics such as mass density and volume fractions of vessels and ray cells on the shear stiffness. Comprehensive microstructural and mechanical data from previous investigations of the same hardwood material support the interpretation of the microstructure–shear stiffness relationships. Mass density was confirmed to be the dominant microstructural characteristic for shear stiffness. Also, ultrasound shear wave propagation velocity increases with density, particularly in the radial-tangential (RT) plane. In addition to density, comparably higher shear stiffness GLR can be explained by comparably higher ray content and lower vessel content. As for GLT, a ring porous structure seems to lead to higher shear stiffness as compared to a diffuse porous structure. For this shear stiffness, vessel and ray content were found to have a less impact. Also, the rolling shear stiffness GRT was found to be higher for a diffuse porous structure than for a ring porous one. Moreover, the data supports that ray cells act as reinforcements in the RT plane and lead to higher GRT

  • 66. Bader, Thomas K.
    et al.
    Hofstetter, Karin
    Technische Universität, Austria.
    Pilzabbau von Holz: Quantifizierung des Steifigkeitsverlusts auf Basis von mikromechanischen Überlegungen2010In: Wiener Holzschutztage 2010: 25. - 26. November 2010, Wien, Wien: Wiener Holzschutztage , 2010, Vol. 28, p. 50-55Conference paper (Other academic)
    Abstract [de]

    Pilzbefall bewirkt eine Zersetzung des Materials durch Mikroorganismen und damit unweigerlich auch eine Veränderung des mechanischen Verhaltens von Holz. Die Auswirkung der mikrostrukturellen Änderungen auf makroskopisch beobachtbare mechanische Materialkennwerte wie Steifigkeit und Festigkeit lassen sich mittels Mehrskalenmodellierung abschätzen und quantifizieren. Die Eignung solcher Mehrskalenmodelle als Prognosewerkzeuge für Dauerhaftigkeitsbetrachtungen wurde im WoodWisdom-Netzwerk „WoodExter“ im Rahmen eines umfangreichen Testprogramms untersucht. Es wurde dabei sowohl ein Braunfäule verursachender Pilz (Gloephyllum trabeum) als auch ein Weißfäule verursachender Pilz (Trametes versicolor) verwendet. Die Vorgehensweise sowie die gewonnenen Einblicke und Erkenntnisse sind in diesem Beitrag zusammengefasst. Nach einer Kurzbeschreibung der hierarchischen Struktur von Holz und deren Modifikation durch Pilze folgt ein Abriss über die verwendeten Verfahren der Mehrskalenmodellierung. Der Schwerpunkt liegt in der Präsentation der Ergebnisse sowie der experimentellen Validierung des Modells durch Vergleich von Messwerten mit zugehörigen Modellvorhersagen. Schließlich werden im Ausblick mögliche Anwendungen der Modellierung skizziert. 

  • 67.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Alfredsen, Gry
    Norwegian Forest and Landscape Institute, Norway.
    Bollmus, Susanne
    Georg-August-University of Göttingen, Germany.
    Changes in microstructure and stiffness of Scots pine (Pinus sylvestris L) sapwood degraded by Gloeophyllum trabeum and Trametes versicolor Part II: Anisotropic stiffness properties2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, no 2, p. 199-206Article in journal (Refereed)
    Abstract [en]

    Fungal decay considerably affects the macroscopic mechanical properties of wood as a result of modifications and degradations in its microscopic structure. While effects on mechanical properties related to the stem direction are fairly well understood, effects on radial and tangential directions (transverse properties) are less well investigated. In the present study, changes of longitudinal elastic moduli and stiffness data in all anatomical directions of Scots pine (Pinus sylvestris) sapwood which was degraded by Gloeophyllum trabeum (brown rot) and Trametes versicolor (white rot) for up to 28 weeks have been investigated. Transverse properties were found to be much more deteriorated than the longitudinal ones. This is because of the degradation of the polymer matrix between the cellulose microfibrils, which has a strong effect on transverse stiffness. Longitudinal stiffness, on the other hand, is mainly governed by cellulose microfibrils, which are more stable agains fungal decay. G. trabeum (more active in earlywood) strongly weakens radial stiffness, whereas T. versicolor (more active in latewood) strongly reduces tangential stiffness. The data in terms of radial and tangential stiffnesses, as well as the corresponding anisotropy ratios, seem to be suitable as durability indicators of wood and even allow conclusions to be made on the degradation mechanisms of fungi.

  • 68.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Alfredsen, Gry
    Norwegian Forest and Landscape Institute, Norway.
    Bollmus, Susanne
    Georg-August-University of Göttingen, Germany.
    Microstructure and stiffness of Scots pine (Pinus sylvestris L) sapwood degraded by Gloeophyllum trabeum and Trametes versicolor Part I: Changes in chemical composition, density and equilibrium moisture content2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, no 2, p. 191-198Article in journal (Refereed)
    Abstract [en]

    Fungal degradation alters the microstructure of wood and its physical and chemical properties are also changed. While these changes are well investigated as a function of mass loss, mass density loss and changes in equilibrium moisture content are not well elucidated. The physical and chemical alterations are crucial when linking microstructural characteristics with macroscopic mechanical properties. In the present article, a consistent set of physical, chemical and mechanical characteristics is presented, which were measured on the same sample before and after fungal degradation. In the first part of this two-part contribution, elucidating microstructure/stiffness-relationships of degraded wood, changes in physical and chemical data are presented, which were collected from specimens of Scots pine (Pinus sylvestris) sapwood degraded by Gloeophyllum trabeum (brown rot) and Trametes versicolor (white rot) for up to 28 weeks degradation time. A comparison of mass loss with corresponding mass density loss demonstrated that mass loss entails two effects: firstly, a decrease in sample size (more pronounced for G. trabeum), and secondly, a decrease of mass density within the sample (more pronounced for T. versicolor). These two concurrent effects are interrelated with sample size and shape. Hemicelluloses and cellulose are degraded by G. trabeum, while T. versicolor was additionally able to degrade lignin. In particular because of the breakdown of hemicelluloses and paracrystalline parts of cellulose, the equilibrium moisture content of degraded samples is lower than that in the initial state.

  • 69.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Keunecke, Daniel
    ETH Zürich, Switzerland.
    Microstructure–Stiffness Relationships of Common Yew and Norway Spruce2012In: Strain, ISSN 0039-2103, E-ISSN 1475-1305, Vol. 48, no 4, p. 306-316Article in journal (Refereed)
    Abstract [en]

    Yew (Taxus baccata L.) exhibits among conifers a unique macroscopic elastic behaviour. For example, it shows a comparatively low longitudinal elastic modulus related to its comparatively high density. We herein explore the microstructural origin of these peculiarities, aiming at the derivation of microstructure–stiffness relationships. We measure stiffness properties of yew at different hierarchical levels and compare them to corresponding stiffnesses of Norway spruce (Picea abies [L.] Karsten). Cell wall stiffness is investigated experimentally by means of nanoindentation in combination with microscopy and thermogravimetric analysis. On the macroscopic level, we perform uniaxial tension and ultrasonic tests. Having at hand, together with previously reported stiffnesses, a consistent data set of mechanical, chemical and physical properties across hierarchical levels of wood, we discuss influences of microstructural characteristics at different scales of observation. Moreover, a micromechanical model is applied to predict trends of effects of the microstructure on the investigated stiffness properties. On the cell wall level, particularly, the amount of cellulose and its orientation – which was earlier reported to be distinctly different for yew and spruce – result in differences between the two considered species. On the macroscopic scale, model predicted effects of the annual ring structure on transverse stiffness and shear stiffness are found to be smaller than effects of the microfibril angle and mass density.

  • 70.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    From lignin to spruce: Poromechanical upscaling of wood strength2011In: 2010 MRS Fall Meeting: Symposium V/NN/OO/PP – Soft Matter, Biological Materials and Biomedical Materials—Synthesis, Characterization and Applications / [ed] A.J. Nolte, K. Shiba, R. Narayan, D. Nolte, Warrendale, Pennsylvania, USA: Materials Research Society, 2011, Vol. 1301, p. 75-80Conference paper (Other academic)
    Abstract [en]

    Wood strength is highly anisotropic, due to the inherent structural hierarchy of the material. In the framework of a combined random-periodic multiscale poro-micromechanics model, we here translate compositional information throughout this hierarchy into the resulting anisotropic strength at the softwood level, based on “universal” elastic properties of cellulose, hemicelluloses, and lignin, and on the shear strength of the latter elementary constituent. Therefore, derivation of the elastic energy in a piece (representative volume element – RVE) of softwood, stemming from homogeneous macroscopic strains prescribed in terms of displacements at the boundary of the RVE and from pressure exerted by water filling the nanoporous space between the hemicelluloses-lignin network within the cell walls, with respect to the shear stiffness of lignin, yields higher order strains in the lignin phase, approximating micro-stress peaks leading to local lignin failure. Relating this (quasi-brittle) failure to overall softwood failure (or strictly speaking, elastic limit of softwood) results in a macroscopic microstructure-dependent failure criterion for softwood. The latter satisfactorily predicts the biaxial strength of spruce at various loading angles with respect to the grain direction. The model also predicts the experimentally well-established fact that uniaxial tensile and compressive strengths, as well as the shear strength of wood, depend quasi-linearly on the cell water content, but highly nonlinearly on the lumen porosity. 

  • 71.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Homogenization and Localization in a Multiscale Microporomechanical Model for Wood Strength2009Conference paper (Other academic)
  • 72.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Multiscale Microporomechanics Model for Estimation of Elastic Limit States of Softwood Materials2009Conference paper (Other academic)
  • 73.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Multiscale Microporomechanics of Softwood: Applications and Experimental Model Validation2010In: IV European Conference on Computational Mechanics (ECCM 2010), Paris, France: European Community on Computional Methods in Applied Sciences (ECCOMAS), 2010Conference paper (Other academic)
  • 74.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    On the Relevance of Lignin Failure for Softwood Strength: a Poromicromechanical Approach2011In: XI International Conference on Computational Plasticity - Fundamentals and Applications, Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 2011Conference paper (Other academic)
  • 75.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Poromechanical scale transitions of failure stresses in wood: from the lignin to the spruce level2010In: Zeitschrift für angewandte Mathematik und Mechanik, ISSN 0044-2267, E-ISSN 1521-4001, Vol. 90, no 10-11, p. 750-767Article in journal (Refereed)
    Abstract [en]

    Wood strength is highly anisotropic, due to the inherent structural hierarchy of the material. In the framework of a combined random-periodic multiscale poro-micromechanics model, we here translate compositional information throughout this hierarchy into the resulting anisotropic strength at the softwood level, based on “universal” elastic properties of cellulose, hemicellulose, and lignin, and on the shear strength of the latter elementary constituent. Relating, through elastic energy-derived higher-order strains in a poromechanical representative volume element, the (quasi-)brittle failure of lignin to overall softwood failure, results in a macroscopic microstructure-dependent failure criterion for softwood. The latter satisfactorily predicts the biaxial strength of spruce at various loading angles with respect to the grain direction. The model also predicts the experimentally well-established fact that uniaxial tensile and compressive strengths, as well as the shear strength of softwood, depend quasi-linearly on the cell water content, but highly nonlinearly on the lumen porosity.

  • 76.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    The poroelastic role of water in cell walls of the hierarchical composite “softwood”2010In: Acta Mechanica, ISSN 0001-5970, E-ISSN 1619-6937, Vol. 217, no 1, p. 75-100Article in journal (Refereed)
    Abstract [en]

    Wood is an anisotropic, hierarchically organized material, and the question how the hierarchical organization governs the anisotropy of its mechanical properties (such as stiffness and strength) has kept researchers busy for decades. While the honeycomb structure of softwood or the chemical composition of the cell wall has been fairly well established, the mechanical role of the cell wall water is less understood. The question arises how its capability to carry compressive loads (but not tensile loads) and its pressurization state affect mechanical deformations of the hierarchical composite “wood”. By extending the framework of poro-micromechanics to more than two material phases, we here provide corresponding answers from a novel hierarchical set of matrix-inclusion problems with eigenstresses: (i) Biot tensors, expressing how much of the cell wall water-induced pore pressure is transferred to the boundary of an overall deformation-free representative volume element (RVE), and (ii) Biot moduli, expressing the porosity changes invoked by a pore pressure within such an RVE, are reported as functions of the material’s composition, in particular of its water content and its lumen space. At the level of softwood, where we transform a periodic homogenization scheme into an equivalent matrix-inclusion problem, all Biot tensor components are found to increase with decreasing lumen volume fraction. A further research finding concerns the strong anisotropy of the Biot tensor with respect to the water content: Transverse components increase with increasing water content, while the relationship “longitudinal Biot tensor component versus volume fraction of water within the wood cell wall” exhibits a maximum, representing a trade-off between pore pressure increase (increasing the longitudinal Biot tensor component, dominantly at low water content) and softening of the cell wall (reducing this component, dominantly at high water contents). Soft cell wall matrices reinforced with very stiff cellulose fibers may even result in negative longitudinal Biot tensor components. The aforementioned maximum effect is also noted for the Biot modulus.

  • 77.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Wikete, Christoph
    de Borst, Karin
    Elastic Properties of Hardwood at Different Length Scales Predicted by Means of a Micromechanical Model2012In: Proceedings of the 6th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012), Vienna University of Technology, Vienna, Austria, Vienna, Austria, 2012Conference paper (Other academic)
  • 78.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Wikete, Christoph
    Jäger, Andreas
    Hofstetter, Karin
    Eberhardsteiner, Josef
    Mechanical Properties and Microstructural Characteristics of Hardwood2010In: COST Action FP 0802 Workshop: Wood Structure/Function-Relationships, 5-8 October, 2010, Hamburg, Germany, Hamburg, Germany, 2010, p. 61-Conference paper (Other academic)
  • 79.
    Bagaoisan, Guts Nacino
    et al.
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Johansson, Emil
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    Plats för plast; ger det mer last?: En fallstudie om byte från stålrör till glasfiberförstärkt plaströr (GRE) ombord på M/T Ekfjord2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This diploma thesis examines whether a change of cargo and ballast piping from steel to glass reinforced epoxy pipes (GRE-­pipes) on the tanker M/T Ekfjord could result in a measurable weight reduction and therefore a lighter displacement. This thesis also examined if this weight loss may contribute to a lower fuel consumption.

    Data regarding the regulations of steel and plastic piping onboard ships was studied; both the classification society’s (DNV GL) and IMO’s rules and recommendations.

    Future Pipe Industries and Favuseal AS, suppliers of GRE-­pipes and PFP (passive fire protection) for fiberglass piping systems were contacted. They provided the information regarding weight and dimensions for GRE-­pipes and which of their products complies with IMO’s and DNV GL’s regulations.

    Using the original drawings and pipe list from M/T Ekfjord, dimensions and weight calculations were performed for cargo and ballast pipes. With calculations done for both the original and the GRE-­pipes, we were able to identify the weight being saved.

    This thesis concludes that the change from steel to GRE piping system results in a weight reduction of 33.79 metric tons. This weight reduction has no major impact on the overall fuel consumption, however the weight saved can be replaced with cargo if space is available in the cargo tanks.

  • 80. Balea, A
    et al.
    Blanco, A
    Fuente, H
    Concepción, M
    Negro, C
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Hosseinpourpia, Reza
    Mai, C
    Tubek-Lindblom, A
    Hansen, P
    Morphology, properties and recyclability of modified fibres and papers with different chemicals at laboratory and pilot plant trials2015In: 46th Congresso Annuale Aticelca, May 28-29, Sestri Levante-Genova, Italy, Aticelca , 2015, p. 23-31Conference paper (Refereed)
    Abstract [en]

    Fibre+ (2012-2015) is a European project aiming to develop potential treatments for recovered fibre modification capable of improving the recyclability and the properties of recycled papers. This study reports on the results on fibre morphology, paper properties and recyclability of fibres and papers modified with different chemicals and approaches from both laboratory and pilot plant trials. Sixteen modification chemical agents were studied in a set of laboratory trials. The raw material used was 100% recycled paper grade from old corrugated board containers (OCC). The laboratory analysis to evaluate the effectiveness of fibre modifications treatments included FBRM for pre-screening of chemicals, preparation of laboratory control and modified handsheets to a target grammage of 80 g/m2, and measurement of the fibre morphology, recyclability and mechanical and physical properties of the modified handsheets. Based on the results of laboratory testing, Fibre+ modifications pilot plant trials were carried out at a FEX paper machine. Furthermore the effect of the better dispersion of the cPAM using an ECOWIRL was studied. The overall laboratory and pilot plant results were promising for further implementation of the Fibre+ modifications at industrial scale and projection of improvements of fibre and paper properties on the performance of packaging products thereof

  • 81.
    Bengtsson, Malin
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Doweyko, Gosia
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Fönsterglas: vilka, var och varför?2006Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [ru]

    På dagens fönsterglasmarknad har produkter med samma funktioner och utseende fått olika namn. Detta är förvirrande och gör det svårt för en person som ska beställa fönsterglas att jämföra olika tillverkares produkter med varandra. Rapporten är tänkt som en översikt på de olika fönsterglasen som finns på marknaden idag och även på sådant som kan bli aktuellt i framtiden. Den berör också sådant som kan vara av värde att veta vid användning av fönsterglas. Målgruppen är alla som kan tänkas ha intresse i ämnet - alltifrån hobbybyggaren till fackmän i byggbranschen. Informationen är sammanställd från böcker, broschyrer, internet och experter på området fönsterglas.

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  • 82.
    Birch, Jens
    et al.
    Linköping University.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Eklund, Per
    Linköping University.
    Ali, Sharafat
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Synthesis and properties of vitreous thin films based on M2+ and M3+ modified silicon oxynitrides.2017In: ICG Annual Meeting & 32nd Sisecam Glass Symposium, Istanbul, Turkey (22-25 October  2017), 2017Conference paper (Refereed)
  • 83. Blanco Suarez, A.
    et al.
    Hansen, P.
    Lopez Exposito, P.
    Thomsson, L.
    Oliver, JV
    Adamopoulos, Stergios
    Quality prediction of board boxes made from recycled paper2009Conference paper (Refereed)
  • 84.
    Blom, Åsa
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sivrikaya, Hüseyin
    Some factors influencing susceptibility to discoloring fungi and water uptake of Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and Oriental spruce (Picea orientalis) 2012In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, no 2, p. 139-144Article in journal (Refereed)
    Abstract [en]

    The heartwood and sapwood from Scots pine (PS), Norway spruce (PA), and Oriental spruce (PO) were tested for susceptibility to discoloring fungi and water uptake. In addition, annual ring width and density were measured. The methods used were Mycologg for testing growth of fungi and a modified version of EN 927-5 to investigate water uptake. For pine, the heartwood showed a lower water uptake and no discoloring fungi growing in the tests. The heartwood had a significantly higher density and smaller annual ring width than the sapwood. In PA the heartwood had significantly lower discoloration than sapwood. The total water uptake in g/m2 was significantly higher in sapwood, but not the calculated moisture content. As for wood properties, the density was significantly higher in sapwood compared to heartwood, although there were no differences in annual ring width. Regarding PO, differences in water uptake could be seen between sapwood and heartwood although the densities were similar. These results show that susceptibility to discoloring fungi and water uptake is hard to correlate to a single inherent property when looking at different wood species.

  • 85.
    Blom, Åsa
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Live storage and drying of storm-felled Norwayspruce (Picea abies, L. Karst.) and Scots pine (Pinussylvestris L.) trees2014In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 9, no 4, p. 209-213Article in journal (Refereed)
    Abstract [en]

    Storm-felled trees left in the forest for a shorter or longer period, affect the quality of the logs. The change in quality ismainly because of attack of fungi and insects, which in turn depends on the moisture content (MC) of the sapwood. Thepurpose of this study was to receive more knowledge about drying of storm-felled trees by investigating how fast winterstorm-felled Norway spruce and Scots pine dried when left in the forest. Sixteen storm-felled spruces with part of the rootsstill in ground contact were selected from three stands and in addition to 10 pines from one of the stands. The trees wereexamined for MC in the sapwood until 21 months after the storm. This study indicates that wind-thrown trees with rootsstill connected to the soil can survive one summer without any value loss caused by draught, fungi and insects. The standconditions can be of importance as the storm-felled trees in the stand, with scattered windthrow, were in best condition afterone year, as they were shadowed by the trees still standing. Comparing spruces and pines with the stand with scatteredwindthrow, pines were more sensitive to drought and reached critical MC earlier.

  • 86.
    Blom, Åsa
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Bergström, Mikael
    Outdoor exposure of untreated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst) wood samples2010In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, no 3-4, p. 204-210Article in journal (Refereed)
    Abstract [en]

    Untreated Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) samples were exposed above ground in a durability test for six years. The samples consisted of three pieces of wood, 22x95x500 mm, screwed together; two pieces lengthwise with a third piece overlapping. Weight was measured, to calculate moisture content (MC), and samples checked regularly for cracks and fungal growth. Parameters investigated were heartwood/sapwood (pine), annual ring orientation (spruce), stand site, annual ring width and density.

    Stand site, annual ring width or density had no influence on MC or fungal growth for neither pine nor spruce. Spruce samples with vertical annual rings had lesser amounts of cracks than samples with horizontal annual rings.

    Regarding pine sapwood samples, they showed high MC and large amount of rot fungi, while heartwood had lower MC and no rot. Most spruce samples were similar to pine heartwood, except from a few samples that had high MC and fungal growth. Those were all sawn from the outer part of the log. Therefore, it can be stated that spruce sawn from the inner part has almost the same properties as pine heartwood while spruce from the outer part of the log has properties similar to pine sapwood.

  • 87.
    Blom, Åsa
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Bergström, Mikael
    Presence of longitudinal cracks in planks from storm-felled pine (Pinus sylvestris L.) and spruce (Picea abies (L.) Karst.)2012In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 7, no 4, p. 237-241Article in journal (Refereed)
    Abstract [en]

    After the severe storm Gudrun in southern Sweden in 2005, a quantitative study was done in order to investigate the presence of lengthwise crack on planks taken from storm-felled trees in southern Sweden, compared to planks from standing trees not subjected to this storm (central Sweden). The main yield from each log was examined. In total, 1087 pine (Pinus sylvestris) planks and 3626 spruce (Picea abies) planks from the storm-struck area were investigated and compared to 1953 spruce and 2000 pine planks from trees outside the storm-struck area. The examination of cracks was done visually on dried planks. For pine, 51.7% of the planks from storm-felled trees had a total length longer than 0.5 m, compared to 7.3% for the reference material. As for spruce, 11.0% of the planks from storm-felled trees had a total crack length of more than 0.5 m, compared to the reference material where 2.2% had cracks longer than 0.5 m. The results show that the storm-felled trees had more longitudinal cracks than the reference material and that pine was more likely to develop storm-related cracks than spruce.

  • 88.
    Blomqvist, Lars
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sandberg, Dick
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Kifetew, Girma
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    The influence of individual veneer orientation on the shape stability of planar lamination2012In: Current and Future Trends of Thermo-Hydro-Mechanical Modification of Wood. Opportunities for new markets? / [ed] Mathieu Pétrissans and Philippe Gérardin, Nancy, France, 2012, p. 160-162Conference paper (Refereed)
  • 89.
    Blyberg, Louise
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lang, Maria
    Glafo, SE-35196 Växjö, Sweden.
    Lundstedt, Karin
    Glafo, SE-35196 Växjö, Sweden.
    Schander, Matilda
    Glafo, SE-35196 Växjö, Sweden.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Silfverhielm, Magnus
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Stålhandske, Christina
    Glafo, SE-35196 Växjö, Sweden.
    Glass, timber and adhesive joints - Innovative load bearing building components2014In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 55, p. 470-478Article in journal (Refereed)
    Abstract [en]

    Structural glass-timber composite beams and shear wall elements were investigated in terms of their mechanical behaviour, energy performance and their LCA performance. The load bearing components were manufactured using annealed float glass which was adhesively bonded to the timber with different adhesives. The results show, among other things, that is is possible to join the two materials glass and timber and obtaining a non-brittle failure of the beams. The shear wall elements have the potential of being used as stabilising elements and load bearing walls in buildings of up to 4 storeys height. It is possible to combine glass and timber in a load bearing shear wall without loss of energy performance of a building or without loosing LCA performance. In addition to these benefits, the timber glass composite wall has, of course the benefit of being transparent.

  • 90.
    Bocko, Jozef
    et al.
    Technical University of Košice, Slovakia.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Nohajová, Viera
    Technical University of Košice, Slovakia.
    Application of Evolutionary Algorithm in Elasticity2015In: Applied Mechanics and Materials, ISSN 1660-9336, E-ISSN 1662-7482, Vol. 816, p. 363-368Article in journal (Refereed)
    Abstract [en]

    This article introduces evolutionary algorithms and their utilization in mechanicalengineering. First part of this work describes evolutionary algorithms and their characteristics. Themain body of evolutionary algorithms, the selection methods for parents and the types ofreproduction are explained in the next part of this article. Termination conditions are also discussed.Finally, the application of evolutionary algorithms to a problem in mechanical engineering isdescribed. Thereby, the material parameters for a Bodner-Partom model describing viscoelastoplasticmaterial behavior are determined by fitting data from experiments on Aluminum testsamples under tension load.

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  • 91.
    Bonarski, Jan T.
    et al.
    Polish Academy of Sciences.
    Olek, Wiesław
    Poznań University of Life Sciences.
    Pospiech, Jan
    Polish Academy of Sciences.
    Kifetew, Girma
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Application of spatial distribution of cellulose crystallites for determining wood anisotropy2012In: Workshop micro-characterisation of wood materials and properties: 24–26 October, 2012 Edinburgh, Scotland, UK, 2012, p. 29-30Conference paper (Refereed)
    Abstract [en]

    The anisotropy of wood properties is related to the ultrastructural organization of wood cell walls. The mean microfibril angle (MFA) is the most obvious parameter quantifying the ultrastructure. Various methods for the MFA measurements have been developed. However, the direct microscopic techniques (both light and electron ones) as well as the indirect X-ray methods were dominating. However, the helical arrangement of cellulose fibrils in wood cells around the longitudinal anatomical direction results in spatial changes of orientations of the lattice planes. Such misorientation between the longitudinal anatomical direction and the microfibril axes has a spatial character and therefore, it can not be correctly described by a single parameter only, i.e. by MFA. The most comprehensive description of the spatial distribution of orientations of cellulose crystallites can be obtained when defining a set of parameters consisting of the rotating axis (given by the polar coordinates θ and ψ and referred to the sample framework) as well as the angle of rotation (ω) around the axis. In order to analyze of wood anisotropy a stereographic projection of the rotating axes on the base of the (010) plane of the lattice cell of cellulose is recommended. Regarding the crystallographic system of the monoclinic lattice of cellulose and the two-fold symmetry of the <010> axis, the projection plane corresponded to the a-c plane of the elementary cell [3]. An example of the projection and the distribution of the rotation axis characterizing the spatial organization of wood microfibrils is given in Fig. 1. The θ, ψ and ω parameters were determined with the original computer program SpaceWood. The parameters were determined regarding the crystallographic symmetry and the parameters of the unit-cell of cellulose given by Zugenmaier [3].

  • 92. Bonnet, Marie
    et al.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Water transport in hardwoods above FSP: case of birch2014Conference paper (Other academic)
  • 93.
    Briggert, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Olsson, Anders
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Oscarsson, Jan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Three-dimensional modelling of knots and pith location in Norway spruce boards using tracheid-effect scanning2016In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 74, no 5, p. 725-739Article in journal (Refereed)
    Abstract [en]

    Knots and the orientation of fibres in timber are decisive for the stiffness and strength of boards. Due to large property variations between members, strength grading is necessary. High resolution information of the orientation of fibres, both on surfaces and within members, would enable development of more accurate grading methods than those available today. A step towards three-dimensional (3D) models of the fibre orientation of the entire board volume is the establishment of 3D knot models based on scanning. The light from a dot laser illuminating the surface of a softwood board will, due to the tracheid effect, spread more along the fibres than across resulting in the dot entering an elliptical shape. In this investigation both the shape of the ellipse and the direction of its major axis were used to estimate the 3D fibre orientation on board surfaces. Knot surfaces were identified where the angle between the estimated 3D fibre direction and an approximated direction of the board’s pith exceeded a threshold value. By means of algorithms based on polar coordinates, knot surfaces which belonged to the same physical knot visible on different sides of the board were identified and as a result the position, orientation and volume of each knot were determined. Based on this information, a more accurate position of the board’s pith along the board was calculated. The established models showed good agreement with physical boards. The models constitute a promising starting point for further development of strength grading methods based on tracheid-effect scanning.

  • 94.
    Bring, Torun
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. kemi.
    Jonson, Bo
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Kemi.
    Kloo, Lars
    Oorganisk Kemi, KTH.
    Potassium sulfate droplets and the origin of turbidity in alabaster glass2006In: Glass Technology : European Journal of Glass Science and Technology A, Vol. 47, no 1, p. 15-18Article in journal (Refereed)
    Abstract [en]

    A study of the criteria required to manufacture multi-component semi-transparent silicate glasses, so called “alabaster” glass, has found that the optical effect is caused by non-crystal¬line potassium sulfate droplets. The droplets were characterized by use of XRD, SEM/EDX and Raman spectroscopy. The size range of the particles is in the order of 5-50 micrometers. It was found that the droplets consisted of potassium sulfate, even if other sulfate compounds were added to the glass. The amount of sulfate compound added, the melting temperature of the furnace and the melting time have significant effect on the optical density of the glass. The optical density of the glass can be correlated to the calculated surface tension of the host glass, suggesting that phase separation of a sulfate enriched liquid phase is part of the mecha¬nism forming the droplets. By adding pigments several different colours can be obtained, but the alabaster effect is not achieved during reducing conditions, thus it seems not possible to produce colours originating from reduced pigments. Pigments tested were Cr, Fe, Co, Cu, Au, Mo/Se, Nd and Ti/Ce/Se.

  • 95.
    Bring, Torun
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. kemi.
    Jonson, Bo
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Kemi.
    Kloo, Lars
    KTH, oorganisk kemi.
    The origin of turbidity in alabaster glasses2006In: Glass:The art of Science: Sunderland 2006, Society of Glass Technology, Sheffield , 2006Conference paper (Refereed)
  • 96.
    Burman, Jonas
    et al.
    University of Kalmar, Kalmar Maritime Academy.
    Friberg, Magnus
    University of Kalmar, Kalmar Maritime Academy.
    Projekt Lister: Överhalning av en hjälpmaskin2008Independent thesis Basic level (professional degree), 5 poäng / 7,5 hpStudent thesis
    Abstract [en]

    ABSTRACT

    This is a summary of the formal part of our project. During the autumn of 2007 and spring 2008 we have done an overhaul on one of the auxiliary engines onboard Calmare Nyckel. The assignment was given from Egon Nilson. The engine was in bad shape, lubrication oil and coolingwater was leaking from several cylinders and thereby in big need of a service. There have been some waiting time during the order of new parts because of the rare engine type which are British and therefore all the parts had to be ordered from England. At the end of the project we discovered some difficulties with coolingwater leaking in to the oil sump, this causing further delays finishing the project. The problem were solved and at the test run the engine run satisfactory.

    During the project we have as far as possible followed the manual and other instructions available.

    During a project like this it is important that all documentation of the project is shown.

    The materials that are shown are presented with an introduction followed by the process and the result. To this documentation we have attached a working diary and quotations.

    Download full text (pdf)
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  • 97.
    Carlsson, Bo
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Suitable indicators in assessment of environmental and climatic performance of solar heating systems - Use of life cycle analysis for purpose of total cost comparisons: Internal report for IEA Solar Heating and Cooling Programme Task 29, Project A22011Report (Other academic)
    Abstract [en]

    To assess climatic performance of energy producing systems, the indicator IPCC, 100a is maybe the most commonly employed in life cycle analysis, LCA. The result is expressed as the amount of green house gases that is emitted to the atmosphere during production of one energy unit as e.g. kg CO2 equivalents per 1 MJ of energy produced or transferred by the system considered. To translate this indicator into cost the rate for green house emission trading in EU would at least in principle be applicable but has not been used for that purpose in connection with product design yet as far as we know.

     

    The analysis of the LCA data on the two solar heating systems found in the Ecoinvent data base shows that the total cost methodology proposed by Carlsson would be a suitable tool to compare performance of different solar heating systems not only in terms of direct costs but also in terms of the indirect costs that can be attributed to the environmental negative impact the life cycles of the solar systems are causing.

     

    The analysis has also shown that to make an adequate comparison between two solar systems with respect to environmental performance or environmental cost, the two systems have to be analysed when operating under the same external conditions with respect to outdoor climate and heat demand. The solar fraction utilized by the systems must be the same which means that only the design and the size of the two systems are different.

  • 98.
    Carlsson, Bo
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Total cost accounting helps reduce resource use in manufacturing - New method to assess product sustainability2011In: Science for Environmental Policy, DG Enviroment News Alert Sevice, no 26, p. 11-Article, review/survey (Other (popular science, discussion, etc.))
  • 99.
    Carlsson, Bo
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Azoulay, Michel
    KTH.
    Nanoteknologi för ökat mervärde till en trähusfasad: Förstudierapport för DISK programmet inom temat Trä får nya egenskaper med nanoteknik2010Report (Other academic)
    Abstract [sv]

    Aktuell rapport redovisar resultatet av en förstudie över hur man med hjälp av nanoteknologi skulle kunna förbättra ytbehandlingen av en trähusfasad så att ett mervärde skapas.

     För ytbehandling finns idag många tillämpningar där nanotekniken utnyttjas för att skapa mervärde hos en yta jämfört med vad dagens mer traditionella produkter kan erbjuda. Nanobaserade ytbehandlingsprodukter marknadsförs idag som uppges göra ytor smuts- och vattenavvisande, förhindrar påväxt av alger, svamp och mossa, med förbättrad UV- och temperaturresistens och kulörbeständighet, förbättrad reptålighet och nötningshärdighet, samt med antigraffiti egenskaper etc.  De flesta produkterna är dock nya och för en del finns därför frågor som gäller t.ex. långtidsprestanda och teknisk livslängd, underhållsbarhet och därmed sammanhängande ekonomi sett ur ett livscykelperspektiv för den produkt eller system där ytbehandlingen utgör bara en del.

     Många nanoteknikbaserade färger som beskrivs i rapporten finns för mineraliska underlag men mycket få kan rekommenderas för ytbehandling av utvändigt trä dock. Mycket utvecklingsarbete pågår emellertid och vår bedömning är att många av de nanoteknikbaserade ytbehandlingsprodukter som idag finns för mineraliska underlag kommer att kunna modifieras för användning också på utvändigt trä inom ett icke alltför avlägsen framtid.

     I förstudien ingick att uppskatta den ekonomiska potentialen för hur ökad funktionalitet hos ett nanoteknologibaserat ytbehandlingssystem skulle kunna ge ett mervärde. Vi fann att mervärdet bäst kan uttryckas i termer av minskade underhållskostnader relativt de som kännetecknar de mer traditionella material och tekniker som idag används för ytbehandling av trähusfasader. Våra slutsatser är att en trähusfasad, som är smutsavvisande och förhindrar påväxt, borde kunna reducera underhållskostnaderna väsentligt genom att minska eller kanske helt eliminera behovet av fasadrengöring mellan två ommålningar. Vilka förbättringar man kan få med dagens nanobaserade ytbehandlingsprodukter i termer av längre underhållsintervaller är svårare att säga men vi bedömer ändock att det borde vara möjligt att åstadkomma kanske så mycket som en 50 % förlängning av intervallet för förnyad ytbehandling.

     För de mest intressanta nanoteknologibaserade ytbehandlingssystemen bedömer vi dock genomförandet av en flerårig fältmässig utvärdering som motiverad. Syften med studien skulle vara att från resultaten uppskatta nödvändigt intervall för fasadtvätt, förnyad ytbehandling och risk för rötangrepp hos de undersökta färgsystemen, utnyttja resultaten också till att uppskatta skillnader i underhållskostnader mellan de nanoteknologibaserade färgsystemen och referenssystem som baserar sig på användning av traditionell ytbehandlingsteknik samt i detta sammanhang även utvärdera färgsystemens underhållsbarhet avseende långtidsegenskaper efter förnyad ytbehandling          

     

  • 100.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Sweden.
    Bolmsjö, Gunnar
    University West, Sweden.
    Thermoelectric method for temperature measurement in friction stir welding2013In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 18, no 7, p. 541-550Article in journal (Refereed)
    Abstract [en]

    Previous research within friction stir welding (FSW) has demonstrated that online control of welding parameters can improve the mechanical properties and is necessary for certain applications to guarantee a consistent weld quality. One approach to control the process is by adapting the heat input to maintain a stable welding temperature, within the specified operating boundaries. This requires accurate in-process temperature measurements. This paper presents a novel method to measure the temperature at the interface of the FSW tool and workpiece. The method is based on the thermoelectric effect between dissimilar materials. The measurements are compared to thermocouple measurements and to a physical model and show good correspondence to each other. Experiments demonstrate that the method can quickly detect temperature variations, due to geometrical variations of the workpiece or due to parameter changes. This allows use of the method for online control of robotic FSW.

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