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  • 151.
    Couceiro, José
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Neyses, Benedikt
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    In-situ moisture content and density measurements in surface densified wood using dual X-ray absorptiometry in medical CT-scanning2016Inngår i: BIOCOMP 2016: The 13th Pacific Rim Bio-Based Composites Symposium, Bio-based composites for a sustainable future., Concepción: University of Concepción , 2016, Vol. 2, s. 92-, artikkel-id NA01Konferansepaper (Fagfellevurdert)
  • 152.
    Couceiro, José
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    The use of X-ray computed tomography in bio-composite research2016Inngår i: BIOCOMP 2016: The 13th Pacific Rim Bio-Based Composites Symposium : Bio-based composites for a sustainable future,, Conceptión: University of Concepción , 2016, s. 42-45Konferansepaper (Fagfellevurdert)
    Abstract [en]

    X-ray computed tomography (CT), which was introduced in the medical field in the early 1970s, is also a powerful tool for the non-destructive measurement of dynamic processes in wood. For more than 20 years, medical CT has been used in wood research at Luleå University of Technology. The uniqueness of the CT equipment allowsprocesses such as drying, modification; water absorption; internal and external cracking; and material deformation to be studied in temperature- and humidity-controlled environments. The data recorded by the CT scanner during the process is converted into two or three dimensional images that, for instance, can show dynamic moisture behaviour in wood drying and crack formation. This paper provides an overview of the possibilities of using CT in bio-composite research, and shows examples of applications and results that can be particularly difficult to achieve using other methods. A specific focus is on studies on wood products that use combinations with materials such as metal and especially about how to deal with the difficulties that this entails.The practical application of the result is that CT scanning, combined with image processing, can be used for non-destructive and non-contact three-dimensional s tudies of exterior construction elements during water sorption and desorption, to study parameters such as swelling and shrinking behaviour; delamination phenomena; and crack development.

  • 153.
    Couceiro, José
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hansson, Lars
    Norwegian University of Science and Technology (NTNU), Department of ICT and Natural Sciences, Norway.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    CT scanning of capillary phenomena in bio-based materials2017Inngår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, nr 4, s. 181-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    X-ray computed tomography (CT) is a powerful tool for the non-destructive study of dynamic moisture processes in wood and other bio-based materials. In the CT facilities at Luleå University of Technology, it is possible to study wood-moisture relations such as water absorption, drying and related material deformation under a temperature- and humidity-controlled environment.An increase in the use of bio-based materials in building construction has led to an increased interest in capillary phenomena in these materials, because of an increasing number of moisture-related damage in timber and hybrid-timber buildings. This article shows some examples of how different bio-materials used in construction interact with liquid water over time. The overall purpose has been to develop the CT technique as a powerful tool for the determination and visualization of capillary flow that can be a base for modelling and an increased understanding of moisture flow in new bio-based building materials.Early-stage observation of the behaviour of different traditional and new bio-based building materials shows that CT scanning, combined with image processing, has a high potential to be used in performing non-destructive and non-contact tests that can help to increase the knowledge of water-material interactions and develop building materials with an optimized performance.

  • 154.
    Cristescu, Carmen
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Markers of quality in self-bonded beech boards2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A self-bonding phenomenon takes place when five layers of beech (Fagus SylvaticaL.) veneers are pressed at temperatures higher than 200ºC. If the pressing temperature between veneer surfaces reaches at least 225ºC during pressing and if the pressure applied is optimal, water-resistant bonds are formed between veneers. This study investigates the relation of thickness reduction (marker of compression) and mass loss (marker of heat treatment intensity) to boards quality. The effect of water and water vapour on the bondings between veneer in boards pressed at 200, 225 and 250ºC is studied. The conclusion is that pressing 5 layers of 2 mm rotary-cut beech veneer parallel-fibered at 225ºC, 5 MPa and 300 s leads to a thickness reduction of 33.4 % and mass loss of 1.23 %; in such boards bondings are not resistant to liquid water but are resistant to vapour after one adsorption-desorption cycle. When pressing at 250ºC, 5 MPa and 300 seconds, the thickness reduction is 50% and the mass loss 4%; in such boards no delamination was observed when soaked in water. Boards pressed athigher temperature show lower hygroscopicity. Their equilibrium moisture content (EMC) rangedbetween 3.6 and 7%. Based on the results of this study it ishypothesised that the decay resistance of self-bonded boards will increase when increasing the severity of the hot-pressing.

  • 155.
    Cristina, Simón
    et al.
    Universidad Politécnica de Madrid - Ciudad Universitaria, Spain.
    Francisco, García Fernández
    Universidad Politécnica de Madrid - Ciudad Universitaria, Spain.
    Luis, García Esteban
    Universidad Politécnica de Madrid - Ciudad Universitaria, Spain.
    Paloma, de Palacios
    Universidad Politécnica de Madrid - Ciudad Universitaria, Spain.
    Hosseinpourpia, Reza
    Georg August University Göttingen, Germany.
    Carsten, Mai
    Georg August University Göttingen, Germany.
    Comparison of the saturated salt and dynamic vapor sorption methods in obtaining the sorption properties of Pinus pinea L.2017Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 75, nr 6, s. 919-926Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several methods are available for obtaining the sorption isotherms of wood. Among these, the saturated salt and dynamic vapor sorption methods are the most frequently used  ones. For the first time, the hygroscopic response of wood obtained using these two methods is compared. This is done by determining the 35 and 50°C adsorption isotherms of juvenile and mature wood of Pinus pinea L. The hygroscopic behavior of the two types of wood is different, as the mature wood has a higher moisture content than the juvenile wood in the isotherms studied. Comparison of the static saturated salt method and dynamic vapor sorption shows few significant differences between the equilibrium moisture content obtained by each method during the adsorption process, both in a point by point comparison and in the comparison of quadratic polynomial forms of the Guggenheim Anderson-de Boer model. Moreover, in both methods the point of relative humidity from which multilayer sorption predominates over monolayer sorption is similar.

  • 156.
    Dahlblom, O.
    et al.
    Lund University.
    Ormarsson, Sigurdur
    Lund University.
    Petersson, H.
    Lund University.
    Simulation of wood deformation processes in drying and other types of environmental loading1996Inngår i: Annales des Sciences Forestieres, ISSN 0003-4312, E-ISSN 1878-6545, Vol. 53, nr 4, s. 857-866Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deformation processes in wood exposed to drying and other types of environmental loading are simulated by use of the finite element method. In the material model applied, the orthotropic structure of the wood material is considered. The differences of properties in the longitudinal, radial and tangential directions for stiffness parameters as well as for moisture shrinkage parameters are taken into account. As an illustration of possible application areas, the deformation development of boards during drying is simulated. In the analyses, the influence of spiral grain and the variation of wood properties with the distance from the pith are considered. The simulation yields information about unfavourable deformations that develop during the drying process., Le processus de déformation du bois exposé au séchage et autres types de charges environnementales est simulé par la méthode des éléments finis. La structure orthotropique du bois est prise en considération sur le modèle de matériel utilisé. Les différences existant au niveau des propriétés des directions longitudinales, radiales et tangentielles sont prises en compte pour les paramètres de rigidité et de contraction par humidité. Une des possibilités du champ d'applications est illustrée par le fait que l'évolution de la déformation des planches pendant le séchage est simulée. À l'échelon des analyses, l'influence du grain spiral et la variation des propriétés du bois avec la distance depuis la moelle sont pris en compte. La simulation permet d'obtenir des informations concernant l'évolution des déformations défavorables pendant le processus de séchage.

  • 157. Dahlblom, Ola
    et al.
    Lindemann, Jonas
    Ormarsson, Sigurdur
    Software for Numerical Simulation of Drying Induced Deformation of Wooden Products2003Inngår i: 8th International IUFRO Wood Drying Conference, TRANSILVANIA University of Brasov, Faculty of Wood Industry , 2003, s. 45-50Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A previously developed computational model for 3D finite element simulations of wood during moisture changes is in the present work provided with a special-purpose graphical user interface. The software is designed to use a personal computer for the graphical user interface and to have possibility to use distributed computational resources for the simulation.

  • 158. Dahlblom, Ola
    et al.
    Ormarsson, Sigurdur
    Petersson, Hans
    Prediction of deformations by an extended two-dimensional formulation1996Inngår i: Quality wood drying through process modelling and novel technologies / [ed] Alain Cloutier, Yves Fortin, 1996, s. 69-76Konferansepaper (Fagfellevurdert)
  • 159.
    Dahlblom, Ola
    et al.
    Lund Institute of Technology, Sweden.
    Persson, Kent
    Lund Institute of Technology, Sweden.
    Ormarsson, Sigurdur
    Petersson, Hans
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Stiffness and shape stability analysis of sawn timber based on experimentally found variations of wood properties1999Inngår i: Connection between Silviculture and Wood Quality through Modelling Approaches and Simulation Softwares, 1999Konferansepaper (Fagfellevurdert)
  • 160.
    Dahlblom, Ola
    et al.
    Lund Institute of Technology, Sweden.
    Persson, Kent
    Lund Institute of Technology, Sweden.
    Petersson, Hans
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Ormarsson, Sigurdur
    Investigation of variation of engineering properties of spruce1999Inngår i: Wood Drying Research & Technology for Sustainable Forestry Beyond 2000, 1999Konferansepaper (Fagfellevurdert)
  • 161.
    Dahlblom, Ola
    et al.
    Lund Institute of Technology.
    Petersson, Hans
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Ormarsson, Sigurdur
    Full 3-D FEM-Simulations of Drying Distortion in Spruce Boards based on Experimental Studies2001Inngår i: 7th International IUFRO Wood Drying Conference, 2001Konferansepaper (Fagfellevurdert)
  • 162.
    Dahlblom, Ola
    et al.
    Lund University, Sweden.
    Petersson, Hans
    Chalmers University of Technology, Sweden.
    Ormarsson, Sigurdur
    Chalmers University of Technology, Sweden.
    Stiffness, strength and shape stability grading analysis of sawn timber based on experimentally found growth characteristics2000Inngår i: World Conference on Timber Engineering, 2000Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Stiffness, strength and shape stability analysis of sawn timber should be based on how the material properties vary in the stem due to different growth conditions. As part of an EU study, results from investigations of the modulus of elasticity, shrinkage coefficient and spiral grain angle of spruce are presented. The variation in properties with the position in the stem has been investigated. The specimens were sawn from 274 stems in 29 stands in five countries of the European Union. A total of about 7000 small specimens were tested. Results from the modelling of stiffness and moisture-induced deformations of battens are presented. The simulations were based on material data obtained from measurements performed on specimens sawn from the same logs as the battens. The simulation results are compared with experimental results and are of interest for the development of new grading procedures for sawn timber.

  • 163. Dahlblom, Ola
    et al.
    Petersson, Hans
    Persson, Kent
    Ormarsson, Sigurdur
    Experimental investigation of basic properties of spruce1998Inngår i: World Conference on Timber Engineering, 1998Konferansepaper (Fagfellevurdert)
  • 164. Dammström, S.
    et al.
    Salmén, Lennart
    RISE., STFI-Packforsk.
    Gatenholm, P.
    On the interactions between cellulose and xylan, a biomimetic simulation of the hardwood cell wall2009Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 4, nr 1, s. 3-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The plant cell wall exhibits a hierarchical structure, in which the organization of the constituents on different levels strongly affects the mechanical properties and the performance of the material. In this work, the interactions between cellulose and xylan in a model system consisting of a bacterial cellulose/glucuronoxylan (extracted from aspen, Populus tremula) have been studied and compared to that of a delignified aspen fiber material. The properties of the materials were analyzed using Dynamical Mechanical Analysis (DMA) with moisture scans together with dynamic Infra Red -spectroscopy at dry and humid conditions. The results showed that strong interactions existed between the cellulose and the xylan in the aspen holocellulose. The same kinds of interactions were seen in a water-extracted bacterial cellulose/xylan composite, while unextracted material showed the presence of xylan not interacting with the cellulose. Based on these findings for the model system, it was suggested that there is in hardwood one fraction of xylan that is strongly associated with the cellulose, taking a similar role as glucomannan in softwood.

  • 165.
    Danesh, Mohammad Amin
    et al.
    Islamic Azad University, Iran.
    Ziaei Tabari, Hassan
    Islamic Azad University, Iran.
    Hosseinpourpia, Reza
    Georg-August University, Germany.
    Nazarnezhad, Noradin
    Sari Agricultural Science and Natural Resources University, Iran.
    Shams, Morteza
    Islamic Azad University, Iran.
    Investigation of the morphological and thermal properties of waste newsprint/recycled polypropylene/nanoclay composite2012Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, nr 1, s. 936-945Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main objective of this research was to study the potential of waste polypropylene and waste newsprint fiber for making wood-plastic nanocomposites. We used 30 wt.% waste newsprint fiber and 10 wt.% compatilizer in this study. Nanoclay was used at two levels: 2.5 and 5% by wt. Materials were mixed with either recycled or virgin polypropylene. The effects of nanoclay (NC) on the mechanical and thermal properties were also studied. The improvements in tensile properties of the blended composites with the addition of NC were further supported by Scanning Electron Microscope (SEM) micrographs and X-Ray Diffraction (XRD) data. Thermal degradation behavior of the composites showed that the degradation temperatures shifted to higher values after addition of nanoclay. The XRD data showed that the relative intercalation of composites with 2.5% nanoclay was higher than 5% nanoclay. The experimental results demonstrated that the waste materials could be used as appropriate alternative raw materials for making low cost wood-plastic composites (WPCs).

  • 166.
    de Borst, Karin
    et al.
    University of Glasgow, UK.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Structure-€“function relationships in hardwood: Insight from micromechanical modelling2014Inngår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 345, s. 78-91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract A micromechanical model is presented that predicts the stiffness of wood tissues in their three principal anatomical directions, across various hardwood species. The wood polymers cellulose, hemicellulose, and lignin, common to all wood tissues, serve as the starting point. In seven homogenisation steps, the stiffnesses of these polymers are linked to the macroscopic stiffness. The good agreement of model predictions and corresponding experimental data for ten different European and tropical species confirms the functionality and accuracy of the model. The model enables investigating the influence of individual microstructural features on the overall stiffness. This is exploited to elucidate the mechanical effects of vessels and ray cells. Vessels are shown to reduce the stiffness of wood at constant overall density. This supports that a trade-off exists between the hydraulic efficiency and the mechanical support in relation to the anatomical design of wood. Ray cells are shown to act as reinforcing elements in the radial direction.

  • 167.
    De Magistris, Federica
    et al.
    RISE., STFI-Packforsk.
    Salmén, Lennart
    RISE., STFI-Packforsk.
    Finite element modelling of wood cell deformation transverse to the fibre axis2008Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, nr 2, s. 240-246Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Modelling of wet wood under compression and combined shear and compression load was performed to simulate the mechanical pulping of wood chips in refiners. Experiments have shown that the wet fibre network exhibit two different deformation modes; an S-shape mode associated with compression and a brick-shape mode associated with combined shear and compression. To study the factors governing the mechanical behaviour of the fibre network a material model with the characteristics originating from the properties of the wood polymers was developed and was used in a three-dimensional finite element analysis. The effects of material properties were investigated by comparing models with anisotropic one-layer cell walls and orthotropic multi-layer cell walls. The deformation achieved both under compression and under combined shear and compression was found to be similar independent of the material constants used or the number of layers of the cells walls. This implies that the most important factor governing the deformation pattern of the fibre network is the cell structure itself.

  • 168.
    Dedic, D.
    et al.
    RISE, Innventia.
    Iversen, T.
    RISE, Innventia.
    Ek, M.
    Cellulose degradation in the Vasa: The role of acids and rust2013Inngår i: Studies in Conservation, ISSN 0039-3630, E-ISSN 2047-0584, nr 4, s. 308-313Artikkel i tidsskrift (Fagfellevurdert)
  • 169.
    Dedic, D.
    et al.
    RISE, Innventia.
    Iversen, T.
    RISE, Innventia.
    Sandberg, T.
    Ek, M.
    Chemical analysis of wood extractives and lignin in the oak wood of the 380 year old Swedish warship vasa2011Konferansepaper (Fagfellevurdert)
  • 170.
    Dedic, Dina
    et al.
    RISE, Innventia.
    Iversen, Tommy
    RISE, Innventia.
    Ek, M.
    Cellulose degradation in the Vasa: The role of acids and rust2013Inngår i: Studies in Conservation, ISSN 0039-3630, E-ISSN 2047-0584, Vol. 58, nr 4, s. 308-313Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The oak timbers of the Swedish warship Vasa are deteriorating. High amounts of oxalic acid have been found along with a low pH and low molecular weight cellulose deep in the wood timbers. The iron-rich surface wood differs from the interior wood in that it displays higher pH and cellulose with higher molecular weight. The objective of this study was to determine why there is a difference in cellulose degradation, pH, and oxalic acid amount between the surface region and the interior of the Vasa timbers. Analysis of cellulose weight average molecular weight by size exclusion chromatography was performed, as well as quantification of oxalic acid and iron by high-performance anion exchange chromatography and atomic emission spectroscopy, respectively. It was found that a decrease in iron content coincides with an increase in oxalic acid concentration and a drop in pH at a certain depth from the wood surface. When iron-rich surface wood samples from the Vasa were mixed with an aqueous solution of oxalic acid, a fast increase of pH over time was observed. Neither interior wood poor in iron nor the fresh oak reference showed the same neutralizing effect during the time of measurement. This indicates that the presence of iron (rust) causes a neutralization of the wood, through the formation of iron(III) oxalato complexes, thus protecting the wood from oxalic acid hydrolysis. This effect was not observed to the same extent for other acids observed in Vasa wood (sulfuric, formic, glycolic, and acetic acids).

  • 171.
    Dedic, Dina
    et al.
    RISE, Innventia.
    Iversen, Tommy
    RISE, Innventia.
    Ek, Monica
    Cellulose degradation in the Vasa - the role of acids and rust2013Inngår i: Studies in Conservation, ISSN 0039-3630, E-ISSN 2047-0584, Vol. 58, nr 4, s. 308-313, artikkel-id 40105Artikkel i tidsskrift (Fagfellevurdert)
  • 172.
    Dedic, Dina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Sandberg, Teresia
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Iversen, Tommy
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Larsson, Tomas
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Analysis of lignin and extractives in the oak wood of the 17th century warship Vasa2014Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, nr 4, s. 419-425Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The wood in the 17th century Swedish warship Vasa is weak. A depolymerization of the wood's cellulose has been linked to the weakening, but the chemical mechanisms are yet unclear. The objective of this study was to analyze the lignin and tannin moieties of the wood to clarify whether the depolymerization of cellulose via ongoing oxidative mechanisms is indeed the main reason for weakening the wood in the Vasa. Lignin was analyzed by solid-state nuclear magnetic resonance [cross-polarization/magic-angle spinning (CP/MAS) C-13 NMR] and by means of wet chemical degradation (thioacidolysis) followed by gas chromatography-mass spectrometry (GC-MS) of the products. No differences could be observed between the Vasa samples and the reference samples that could have been ascribed to extensive lignin degradation. Wood extracts (tannins) were analyzed by matrix- assisted laser desorption ionization (MALDI) combined with time-of-flight (TOF) MS and C-13 NMR spectroscopy. The wood of the Vasa contained no discernible amounts of tannins, whereas still-waterlogged Vasa wood contained ellagic acid and traces of castalagin/vescalagin and grandinin. The results indicate that the condition of lignin in the Vasa wood is similar to fresh oak and that potentially harmful tannins are not present in high amounts. Thus, oxidative degradation mechanisms are not supported as a primary route to cellulose depolymerization.

  • 173.
    Deshpande, Raghu
    et al.
    MoRe Research, SE-89122 Örnsköldsvik, Sweden.
    Giummarella, Nicola
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. Wallenberg Wood Science Center.
    Germgård, Ulf
    Karlstad University, SE-65188 Karlstad, Sweden.
    Sundvall, Lars
    MoRe Research, SE-89122 Örnsköldsvik, Sweden.
    Grundberg, Hans
    Domsjö Fabriker, SE-89186 Örnsköldsvik, Sweden.
    Lawoko, Martin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    The reactivity of lignin carbohydrate complex (LCC) during manufacture of dissolving sulfite pulp from softwood2018Inngår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 115, s. 315-322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The presence of covalent bonds between lignin and polysaccharides was investigated in dissolving pulps made with one-stage and two-stage acidic sulfite pulping for 100% pine heartwood raw material. The covalent bonds between lignin and pulp polysaccharides occurred mainly to xylan and glucomannan and were of the phenyl glycosides and γ–esters types. The α-ethers that are common in wood were missing in the studied pulp samples. Based on these findings and known lignin reactions during sulfite pulping, a mechanism explaining the absence of the α-ethers is discussed. It is suggested that the lignin carbohydrate bonds may play a vital role in lignin recalcitrance.

  • 174.
    Dorn, Michael
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Bader, Thomas K.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Non-Linear Connection Models in Timber Engineering2016Inngår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE) / [ed] J. Eberhardsteiner, W. Winter, A. Fadai, M. Pöll, Vienna University of Technology, Austria , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this contribution, a numerical model for connections in engineered timber structures, using specially designed connection elements, is presented. The model considers the non-linear load-displacement relation typical for many types of connections on different levels and is presented on the example of dowel-type connections. The structural levels investigated herein are a) the embedment behaviour of a dowel into wood; b) the behaviour of a singledowel connection; and c) a multi-dowel connection under a general load case typical for structural applications. A special characteristic considered in the formulation of the connector elements is the unloading behaviour, which is characterized by an initial high unloading stiffness but a very low stiffness when the load is fully removed. The latter is due to remaining permanent deformations in the wood as well as in the metal connector. The modelling approach was found to correlate well with experimental data and gave new insight in the behaviour of dowel connections, particularly as regards the unloading and reloading behaviour with alternating load directions on the single-dowel connection scale.

  • 175.
    Dvinskikh, Sergey V.
    et al.
    Royal Institute of Technology KTH, Division of Physical Chemistry and Industrial NMR Centre, SE-100 44 STOCKHOLM, .
    Furó, István
    Royal Institute of Technology KTH, Division of Physical Chemistry and Industrial NMR Centre, SE-100 44 STOCKHOLM, .
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Söderström, Ove
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Moisture content profiles and uptake kinetics in wood cladding materials evaluated by a portable nuclear magnetic resonance spectrometer2011Inngår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, nr 3, s. 119-127Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have evaluated the capability of nuclear magnetic resonance (NMR) technology based on small portable magnets for in situ studies of the local moisture content in wood. Low field and low resolution 1H NMR with a unilateral permanent magnet was used to monitor and map the moisture content of wood cladding materials of various types in a spatially resolved manner. The results show that portable NMR equipment based on small open-access permanent magnets can be successfully used for non-invasive monitoring of the moisture content in various extended wood specimens. The moisture content was measured with a depth resolution of 0.2 mm and a maximum penetration depth of 3 mm. This makes the technique suitable for e.g. in situ local moisture content measurements beneath a coating layer in the claddings and it is also possible to relate the moisture level to specific properties of the wood material.

  • 176. Eder, M.
    et al.
    Arnould, O.
    Dunlop, J.W.C.
    Hornatowska, J.
    RISE, Innventia.
    Salmen, L.
    RISE, Innventia.
    Experimental micromechanical characterisation of wood cell walls2013Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, nr 1, s. 163-182Artikkel i tidsskrift (Fagfellevurdert)
  • 177.
    Eitelberger, Johannes
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    Vienna University of Technology, Austria.
    Jäger, Andreas
    Vienna University of Technology, Austria.
    Multiscale prediction of viscoelastic properties of softwood under constant climatic conditions2012Inngår i: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 55, s. 303-312Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper covers the development and validation of a multiscale homogenization model for linear viscoelastic properties of wood. Starting point is the intrinsic structural hierarchy of wood, which is accounted for by several homogenization steps. Using the correspondence principle, an existing homogenization model for the prediction of elastic properties of wood is adapted herein for upscaling of viscoelastic characteristics. Accordingly, self-consistent, Mori–Tanaka, and unit-cell-based techniques are employed, leading to pointwise defined tensorial creep and relaxation functions in the Laplace-Carson domain. Subsequently, these functions are back-transformed into the time domain by means of the Gaver-Stehfest algorithm. With this procedure the orthotropic macroscopic creep behavior of wood can be derived from the isotropic shear behavior of the lignin-hemicellulose phase. A comparison of model predictions for viscoelastic properties of softwood with corresponding experimentally derived values yields very promising results and confirms the suitability of the model.

  • 178.
    Ekevad, Mats
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Huber, Johannes A.J.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Jacobsson, Peter
    Martinsons Träbroar AB.
    Mechanics of stress-laminated timber bridges with butt end joints2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A number of variants of single span and three-span stress-laminated timber bridge decks have been studied via finite element simulations and experiments. Glulam beams in the decks were in general shorter than the total length of span which means that there were butt end joints in the decks. The butt end of each beam in a joint was not connected to the other beam which means that each butt end joint reduced the strength and stiffness of the whole of the deck. Results for deflection and stresses were examined for the studied variants in the form of reduction factors for strength and stiffness relative to a deck without butt end joints.

    Factors are shown in diagrams as function of ratio butt end distance/beam width and also butt end distance/span width. Comparison of achieved results with existing Eurocode rules shows that Eurocode rules are not totally appropriate.

  • 179.
    Eliasson, Lars
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Ställ krav på virket: Rätt virke för produktion i framtidens trähusfabrik2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [sv]

    Denna avhandling behandlar den svenska trähusbranschens behov och möjligheter att erhålla trämaterial med egenskaper som uppfyller de krav som produktion och slutkund ställer. Ett gemensamt problem för den svenska trähusbranschen är de kvalitetsbrister hos det virke sombranschens företag köper för sin produktion, som kan resultera i merkostnader för branschen med 100 MSEK årligen.

    Trähusföretagen uttrycker en viss uppgivenhet över bemötandet från virkesleverantörerna. Virkesleverantörerna å sin sida menar att köparna av trämaterial inklusive företagen i trähusbranschen i ringa utsträckning genomför reklamationer. Avgörande för genomförda virkesaffärer är ofta priset – det blir affär med den som erbjuder lägst pris. Sammantaget innebär detta att det inte blir någon dialog mellan leverantör och köpare som utvecklar synsättet på trämaterialkvalitet.

    Avhandlingsarbetet har bland annat behandlat beredning av träråvaran till färdiga ämnen t.ex. studier vid tillverkning av kvistfria ämnen. Resultatet av arbetet visar på vikten av att genomföra utvärderingar av material och leverantörer. Resultatet visar vidare att kapkostnaden för färdiga träämnen inkl. spill är ca 1/3 av ämneskostnaden. Dock är kostnaden för trämaterialet låg i relation till totalkostnaden för det färdiga huset vilket innebär att ett högre pris för ett virke som fullt ut motsvarar kravspecifikationerna i liten utsträckning påverkar totalkostnaden för huset.

    Råd till trähusbranschen är att ställa krav på virkesråvaran, utvärdera material och leverantörer samt att trähusbranschen ska sikta mot att bli en modern tillverkningsindustri i likhet med de mest framgångsrika inom verkstadsindustrin.

  • 180.
    Eliasson, Lars
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Trähusföretag tappar fördel i slarvig tillverkning.2011Inngår i: Husbyggaren, ISSN 0018-7968, nr 7, s. 24-27Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    BYGGMETODER Ska trä öka sin konkurrenskraft måste trähusföretag och virkesleverantörer bli bättre på att både ställa och uppfylla kravspecifikationer. Idag kan materialspill och felleveranser uppgå till närmare en femtedel av virkeskostnaden.

    Trähusbranschen står inför ett antal utmaningar. Avgörande är att kunna producera attraktiva bostäder till en kostnad som inte är högre än att människor har råd.

    Trähusföretagen utnyttjar inte fullt ut material och metoder som är anpassade för en effektiv produktion av hus i fabrik. I den kontexten får träets miljöfördelar en underordnad betydelse i konkurrensen med andra mindre miljömässigt uthålliga material.

  • 181. Engelund, E.T.
    et al.
    Salmen, L.
    RISE, Innventia.
    Tensile creep and recovery of Norway spruce influenced by temperature and moisture2012Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, nr 8, s. 959-965Artikkel i tidsskrift (Fagfellevurdert)
  • 182.
    Englund, Finn
    et al.
    SP Technical Research Institute of Sweden, Wood Technology.
    Hill, Callum A.S.Militz, HolgerSegerholm, B. KristofferKTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Proceedings of the Fourth European Conference on Wood Modifications2009Konferanseproceedings (Fagfellevurdert)
  • 183. Eriksson, John
    et al.
    Ormarsson, Sigurdur
    Chalmers University of Technology, Sweden.
    Petersson, Hans
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Adaptive Finite Element Analysis of Non-linear Moisture Flow and Associated Distortion Behaviour in Wood2003Inngår i: ADMOS Conference on Adaptive Modelling and Simulation, 2003Konferansepaper (Fagfellevurdert)
  • 184.
    Eriksson, John
    et al.
    Chalmers University of Technology.
    Ormarsson, Sigurdur
    Chalmers University of Technology.
    Petersson, Hans
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    An experimental and numerical study of the shape stability in glued columns2005Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 63, nr 6, s. 423-429Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study concerns the question of how the shape stability features of laminated columns of Norway spruce can be improved in terms of twist through optimal orientation of the individual laminates. Both experimental testing and numerical simulations were employed for evaluating twist stability. In all the columns studied, deformations were measured experimentally at different moisture content levels. A number of columns were also selected for numerical analysis in order to obtain a more thorough understanding of the twist behavior involved, their geometries and material properties of interest being determined. The experimental results showed the twist stability of the columns to be highly dependant upon the internal orientation of the individual laminates. It was also found that high quality columns in terms of shape stability could be manufactured, even when the center-core material has a strong twist tendency. The numerical simulations performed were in close agreement with the experimental results.

  • 185.
    Eriksson, John
    et al.
    Chalmers University of Technology.
    Ormarsson, Sigurdur
    Chalmers University of Technology.
    Petersson, Hans
    Chalmers University of Technology.
    Experimental study of shape stability in glued boards2004Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 62, nr 3, s. 225-232Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An experimental study of shape stability in wooden glued boards was performed to verify certain results of particular interest obtained earlier in numerical simulations. Possibilities for achieving products of good shape stability by gluing boards together in an optimal way are discussed. Since twist is often the most serious form of distortion defects for the user, it was the main type of board deformation considered. Three types of glued products were tested. The experiments show clearly that glued boards can be produced that remain stable in shape when exposed to extreme variations in moisture. The results agree well with the numerical simulations performed earlier. It was found that initial twist could be reduced by proper application of pressure during gluing and that through gluing the occurrence of cracking defects on visible surfaces could be substantially reduced.

  • 186.
    Eriksson, John
    et al.
    Chalmers University of Technology .
    Ormarsson, Sigurdur
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Chalmers University of Technology .
    Petersson, Hans
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Finite element analysis of coupled nonlinear heat and moisture transfer in wood2006Inngår i: Numerical Heat Transfer, Part A Applications, ISSN 1040-7782, E-ISSN 1521-0634, Vol. 50, nr 9, s. 851-864Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A nonlinear model for analysing heat and moisture flow in wood during drying below the fiber saturation point is presented. The model used considers wood at a macro level without taking the various moisture transports mechanisms at the microscopic level into account. Based on the finite-element method, a coupled system of equations resulting from the adopted heat and moisture transfer equations is established and an iterative scheme is proposed. The numerical procedure is verified by a test example. In a two-dimensional analysis, the influence of the coupling on the combined heat and moisture transfer is studied for a board subjected to a typical kiln-drying condition. How well the results agree with those obtained by introducing a commonly applied simplification is discussed.

  • 187. Escalante, Alfredo
    et al.
    Goncalves, Ana
    Bodin, Aase
    Stepan, Agnes
    Sandstrom, Corine
    Toriz, Guillermo
    Gatenholm, Paul
    Wallenberg Wood Sci Ctr, Chalmers, Sweden.
    Flexible oxygen barrier films from spruce xylan2012Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, nr 4, s. 2381-2387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Arabinoglucuronoxylan was extracted from Norway spruce and films prepared by casting from aqueous solution. The sugar analysis and NMR confirmed that the spruce xylan was composed of arabinose, 4-O-methyl-glucuronic acid and xylose in a ratio of 1:2:11 respectively. Substitutions of 4-O-methyl-alpha-D-GlcpA at O-2 and of alpha-L-Araf at O-3 on the xylose backbone were found by NOE analysis. NOE cross-peaks indicated as well that there is at least one free xylose on the main chain present between two substitutions. Whether the distribution of side chains was random or in blocks was uncertain. The average molecular weight of the sample was determined by size exclusion chromatography to be 12,780 g/mol. Arabinoglucoronoxylan casting yielded transparent flexible films with an average stress at break of 55 MPa, strain at break of 2.7% and a Young's Modulus 2735 MPa. Wide-angle X-ray scattering analysis showed that the arabinoglucuronoxylan films were totally amorphous. Addition of sorbitol as plasticizer resulted in less strong but more flexible films (strain at break of 5%). Peaks of crystallinity could be seen in X-ray which corresponds to sorbitol crystallizing in distinct phases. The dynamic mechanical analysis showed that the arabinoglucuronoxylan film softened at a later relative humidity (80% RH) in comparison with plasticized films (60% RH). The films showed low oxygen permeability and thus have a potential application in food packaging.

  • 188.
    Escamez, Sacha
    et al.
    Umeå University, Sweden.
    Latha Gandla, Madhavi
    Umeå University, Sweden.
    Derba-Maceluch, Marta
    SLU Swedish University of Agricultural Sciences, Sweden.
    Lundqvist, Sven-Olof
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia.
    Mellerowicz, Ewa J.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Jönsson, Leif J.
    Umeå University, Sweden.
    Tuominen, Hannele
    Umeå University, Sweden.
    A collection of genetically engineered Populus trees reveals wood biomass traits that predict glucose yield from enzymatic hydrolysis2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, nr 1, artikkel-id 15798Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wood represents a promising source of sugars to produce bio-based renewables, including biofuels. However, breaking down lignocellulose requires costly pretreatments because lignocellulose is recalcitrant to enzymatic saccharification. Increasing saccharification potential would greatly contribute to make wood a competitive alternative to petroleum, but this requires improving wood properties. To identify wood biomass traits associated with saccharification, we analyzed a total of 65 traits related to wood chemistry, anatomy and structure, biomass production and saccharification in 40 genetically engineered Populus tree lines. These lines exhibited broad variation in quantitative traits, allowing for multivariate analyses and mathematical modeling. Modeling revealed that seven wood biomass traits associated in a predictive manner with saccharification of glucose after pretreatment. Four of these seven traits were also negatively associated with biomass production, suggesting a trade-off between saccharification potential and total biomass, which has previously been observed to offset the overall sugar yield from whole trees. We therefore estimated the "total-wood glucose yield" (TWG) from whole trees and found 22 biomass traits predictive of TWG after pretreatment. Both saccharification and TWG were associated with low abundant, often overlooked matrix polysaccharides such as arabinose and rhamnose which possibly represent new markers for improved Populus feedstocks.

  • 189.
    Esteban, Luis García
    et al.
    Ciudad Universitaria, Spain.
    Simón, Cristina
    Ciudad Universitaria, Spain.
    Fernández, Francisco García
    Ciudad Universitaria, Spain.
    Palacios, Paloma de
    Ciudad Universitaria, Spain.
    Martín-Sampedro, Raquel
    Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain.
    Eugenio, María Eugenia
    Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain.
    Hosseinpourpia, Reza
    Georg August University, Germany.
    Juvenile and mature wood of Abies pinsapoBoissie: sorption and thermodynamic properties2015Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 49, nr 4, s. 725-738Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For industrial processes, it is important to study the hygroscopicity and thermodynamic properties of juvenile and mature wood. Samples of Abies pinsapo Boiss. collected in the natural areas of the species in Spain were used to study these properties in both types of wood. The equilibrium moisture contents were obtained, and the 15, 35 and 50 °C isotherms were plotted following the Guggenheim–Anderson–Boer–Dent model. The thermodynamic parameters were calculated using the integration method of the Clausius–Clapeyron equation. Chemical analyses, infrared spectra and X-ray diffractograms were applied to assess chemical modifications and possible changes in the cell wall structure. The chemical composition of the mature wood shows a decrease in the lignin and hemicelluloses content and an increase in the extracts and α-cellulose. The sorption isotherms for the three temperatures studied are higher in the mature wood than in the juvenile wood. Causes of this include the higher content of α-cellulose, the higher crystallinity index and the shorter crystallite length in the mature wood. No difference was found between the juvenile and mature wood in relation to the point of inflexion where the multilayer starts to predominate over the monolayer (approximately 30 %). In terms of the thermodynamic properties, the heat involved is greater in desorption than in adsorption, and more heat is involved in the mature wood than in the juvenile wood.

  • 190. Fackler, K.
    et al.
    Stevanic, Jasna S.
    RISE., Innventia.
    Ters, T.
    Hinterstoisser, B.
    Schwanninger, M.
    Salmén, Lennart
    RISE., Innventia.
    Localisation and characterisation of incipient brown-rot decay within spruce wood cell walls using FT-IR imaging microscopy2010Inngår i: Enzyme and microbial technology, ISSN 0141-0229, E-ISSN 1879-0909, Vol. 47, nr 6, s. 257-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spruce wood that had been degraded by brown-rot fungi (Gloeophyllum trabeum or Poria placenta) exhibiting mass losses up to 16% was investigated by transmission Fourier transform infrared (FT-IR) imaging microscopy. Here the first work on the application of FT-IR imaging microscopy and multivariate image analysis of fungal degraded wood is presented and the first report on the spatial distribution of polysaccharide degradation during incipient brown-rot of wood. Brown-rot starts to become significant in the outer cell wall regions (middle lamellae, primary cell walls, and the outer layer of the secondary cell wall S1). This pattern was detected even in a sample with non-detectable mass loss. Most significant during incipient decay was the cleavage of glycosidic bonds, i.e. depolymerisation of wood polysaccharides and the degradation of pectic substances. Accordingly, intramolecular hydrogen bonding within cellulose was reduced, while the presence of phenolic groups increased.

  • 191. Fackler, K.
    et al.
    Stevanic, J.S.
    RISE, Innventia.
    Ters, T.
    Hinterstoisser, B.
    Schwanninger, M.
    Salmen, L.
    RISE, Innventia.
    FT-IR imaging microscopy to localise and characterise simultaneous and selective white-rot decay within spruce wood cells2011Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, nr 3, s. 411-420Artikkel i tidsskrift (Fagfellevurdert)
  • 192.
    Fall, Andreas
    et al.
    Department of Fiber Technology, KTH.
    Lindström, Stefan B
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik. Linköpings universitet, Tekniska högskolan.
    Sprakel, Joris
    Wågberg, Lars
    Department of Fiber Technology, KTH.
    A physical cross-linking process of cellulose nanofibril gels with shear-controlled fibril orientation2013Inngår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 9, s. 1852-1863Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose nanofibrils constitute the smallest fibrous components of wood, with a width of approximately 4 nm and a length in the micrometer range. They consist of aligned linear cellulose chains with crystallinity exceeding 60%, rendering stiff, high-aspect-ratio rods. These properties are advantageous in the reinforcement components of composites. Cross-linked networks of fibrils can be used as templates into which a polymer enters. In the semi-concentrated regime (i.e. slightly above the overlap concentration), carboxy methylated fibrils dispersed in water have been physically cross-linked to form a volume-spanning network (a gel) by reducing the pH or adding salt, which diminishes the electrostatic repulsion between fibrils. By applying shear during or after this gelation process, we can orient the fibrils in a preferred direction within the gel, for the purpose of fully utilizing the high stiffness and strength of the fibrils as reinforcement components. Using these gels as templates enables precise control of the spatial distribution and orientation of the dispersed phase of the composites, optimizing the potentially very large reinforcement capacity of the nanofibrils.

  • 193.
    Florisson, Sara
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    The effect of initial green state moisture gradients on stresses in timber boards during drying2016Inngår i: Eccomas 2016 Proceedings, 2016Konferansepaper (Fagfellevurdert)
  • 194.
    Florisson, Sara
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    The effect of surface emission, diffusion and initial moisture profiles on stress development in timber boards2017Inngår i: CompWood 2017 : Computational Methods in Wood Mechanics – from Material Properties to Timber: Programme & book of abstract, TU Verlag , 2017Konferansepaper (Fagfellevurdert)
  • 195. Franceschini, T.
    et al.
    Lundqvist, S.-O.
    RISE, Innventia.
    Bontemps, J.-D.
    Grahn, T.
    RISE, Innventia.
    Olsson, L.
    RISE, Innventia.
    Evans, R.
    Leban, J.-M.
    Empirical models for radial and tangential fibre width in tree rings of Norway spruce in north-western Europe2012Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, nr 2, s. 219-230Artikkel i tidsskrift (Fagfellevurdert)
  • 196. Fransson, Jonas
    et al.
    Olsson, Axel
    Witten, Thomas
    Blom, Åsa
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Sandberg, Dick (red)
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Svenska barr- och lövträd: - Andvändning och anatomi2007Rapport (Annet vitenskapelig)
    Abstract [sv]

    Svenska barr- och lövträd – användning och anatomi beskriver

    egenskaper, samt strukturen på makro- och mikronivå för de vanligaste

    svenska trädslagen. Barrträden som behandlas är tall, gran och en.

    Lövträden är björk, asp, al, rödbok, ek, ask och lönn. De fysikaliska

    egenskaperna rangordnas mellan de olika träslagen, för att lätt kunna göra

    jämförelse dem emellan. Dessutom ges exempel på användningsområden

    för respektive träslag. Arbetet baseras på en litteraturstudie av svensk och

    internationell litteratur, samt på egna undersökningar av trä på

    mikroskopisk nivå. Alla träslag med undantag av asp, al och lönn

    presenteras tillsammans med egna bilder tagna i mikroskop.

    I en allmän del beskrivs trädens uppbyggnad på makroskopisk nivå.

    Makroskopisk struktur som beskrivs är t ex märg, årsringar och kärl. I

    denna del beskrivs också olika celltyper, cellens anatomi och kemi. En

    uppdelning är gjord mellan barr- och lövträd. Lövträden i sig delas vidare

    upp i strökärliga, halvströkärliga och ringkärliga träslag.

  • 197.
    Fredriksson, Magnus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Technical solutions to increase competitiveness of cross-laminated timber from the Nordic countries: an overview2018Konferansepaper (Fagfellevurdert)
  • 198.
    Fredriksson, Magnus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Using a Gaussian filter to reduce the effect of positioning errors when optimizing sawing of CT scanned Scots pine and Norway spruce logs2017Inngår i: International Wood Machining Seminar (IWMS-23), 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Computed tomography (CT) scanning of logs is being introduced in sawmills, so there is reason to study how log positioning can be controlled using information from CT. However, positioning errors affect this positioning optimization in a negative way. To reduce this effect, a method was developed using sawing simulation, where logs were sawn in a large number of positions, varying rotation and centering. This resulted in three-dimensional surfaces, with the sawn timber value, rotation and centering on the axes. The surfaces were filtered with a Gaussian filter using a distribution corresponding to that of the positioning error. The filtered values were used for optimization, choosing the global maximum. This resulted in a value recovery that was about two percent higher compared to a simpler optimization without filtering, for a normally distributed rotational error of 5 – 15° standard deviation and a ditto centering error of 3.5 – 10.5 mm standard deviation. This was tested using sawing simulation, using the optimal log position for the two methods, with an added positioning error. Furthermore, the robust method has been tested on a smaller number of rotational positions, starting from horns down, to reduce the number of necessary calculations. The result of this was that at least ± 60 ° in the rotational direction should be evaluated for the robust method to result in a higher recovery than the simpler optimization. The robust method was better than sawing horns down and centered, no matter the positioning error, using only 65 evaluated positions per log.

  • 199.
    Fredriksson, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Broman, Olof
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Factors Affecting Volume Yield in a Forestry-Wood Value Chain: A Simulation Study Based on CT Scanning2017Inngår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, nr 4, s. 540-548Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper presents the results of a simulation study, where log models based on CT scanned logs of Scots pine (Pinus sylvestris L.) was used as input material to a computer simulation model of a generic value chain involving sawing, drying, crosscutting and finger jointing. The aim was to investigate which factors that affect the volume yield in the value chain, be it forestal, log-, process- or quality-related factors. The results show that factors related to growth conditions and log size have a large impact on the volume yield in the studied value chain, together with quality requirements on knots. Factors such as sawing positioning and log quality had a much smaller impact. It can be concluded that it is possible to model a forestry-wood value chain, while assessing which input variables affect the result in terms of volume yield, using CT scanning of logs and subsequent computer simulation of the production processes.

  • 200.
    Fredriksson, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Broman, Olof
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    The Use of CT-Scanning Technology in Wood Value-Chain Research and in Wood Industry: A State of The Art2017Inngår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, nr 4, s. 533-539Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    X-ray computed tomography (CT) is a powerful tool for the non-destructive  measurement  of  dynamic  processes in wood. After more than 25 years of research at Luleå University of Technology in the field of CT-scanning of wood material, the first industrial CT-scanners are now installed in sawmill production for the in-situ measurement of internal  log features to steer of the sawmill process with the help of this information.This  paper  provides  an  overview  of  the  potential  of  CT-scanning in wood-material  research  and  how  this data can be used for the modelling and simulation of the wood value chain. A database of CT-images of trees  is  used  to  create  a  log  model  including  the  outer  shape  of  the  logs  and  their  internal  knot  structure.  Simulation software is used to saw these virtual logs in different positions relative to the sawblade, and also for the crosscutting of the sawn timber to components. The output is dimensions and grades of sawn timber, volume yield as well as an economic result based on real economic conditions. A specially designed climate chamber  for  CT  studies  of  the  drying  of  sawn  timber  is  used  to  increase  the  knowledge  of  how  the  drying  affects the response from the sawn timber during seasoning.

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