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  • 1.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Larissa, Greece.
    Gellerich, A
    Georg-August-University Göttingen, Germany.
    Mantanis, G
    Technological Educational Institute of Larissa, Greece.
    Kalaitzi, T
    Aristotle University of Thessaloniki, Greece.
    Militz, H
    Georg-August-University Göttingen, Germany.
    Resistance of Pinus leucodermis heartwood and sapwood against the brown-rot fungus Coniophora puteana2012In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 7, no 4, p. 242-244Article in journal (Refereed)
    Abstract [en]

    This study assessed the decay resistance of Pinus leucodermis wood to the brown-rot fungus Coniophora puteana. Based upon the median weight losses of 30.65% for heartwood and of 34.68% for sapwood obtained in the biological tests, both the heartwood and sapwood material examined was classified as not durable (durability class 5) according to the CEN/TS 15083-1 classification. Total extractives were low, 3.93% in heartwood and 1.00% in sapwood, while lignin content was 22.60% and 25.41% in heartwoodand sapwood, respectively. It is highly recommended to use protective treatments before using P.leucodermis wood in outdoor conditions.

  • 2.
    Altgen, Michael
    et al.
    University of Göttingen, Germany.
    Adamopoulos, Stergios
    University of Göttingen, Germany.
    Militz, Holger
    University of Göttingen, Germany.
    Wood defects during industrial-scale production of thermally modified Norway spruce and Scots pine2017In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 1, p. 14-23Article in journal (Refereed)
    Abstract [en]

    This research investigates wood defects, particularly the formation of surface cracks, during the production of thermally modified wood and its exposure to cyclic moisture changes. Boards of Norway spruce and Scots pine originating from different steps within the production of ThermoWood® were collected and wood defects were investigated at macroscopic and microscopic scale. Subsequently, the wood was exposed to capillary wetting cycles to record its sensitivity towards cracking. After the modification process, typical anatomical defects of conventional kiln-drying became more frequent and severe, with the magnitude being to some extent depending on the presence of defects in the raw material. At microscopic scale, damages to ray parenchyma and epithelial cells as well as longitudinal cracks within the cell walls of earlywood tracheids were evident in thermally modified wood. Despite a lower water uptake and higher dimensional stability, thermally modified wood was more sensitive to surface cracking during wetting cycles than unmodified wood, i.e. at the outside face of outer boards (near bark). For limiting surface cracking of thermally modified wood during service life, the use of high-quality raw material, the exposure of the inside face of the boards (near pith) and the application of a surface coating are considered beneficial.

  • 3.
    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

  • 4.
    Bader, Thomas K.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology. Vienna University of Technology, Austria.
    Schweigler, Michael
    Vienna University of Technology, Austria.
    Hochreiner, Georg
    Vienna University of Technology, Austria.
    Serrano, Erik
    Lund University, Sweden.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Dowel deformations in multi-dowel LVL-connections under moment loading2015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 3, p. 216-231Article in journal (Refereed)
    Abstract [en]

    The aim of the experimental study presented herein is the assessment and quantification of the behavior of individual dowels in multi-dowel connections loaded by a bending moment. For this purpose, double-shear, steel-to-timber connections with nine steel dowels arranged in different patterns and with different dowel diameters were tested in four-point bending. In order to achieve a ductile behavior with up to 7° relative rotation, the connections were partly reinforced with self-tapping screws. The reinforcement did not influence the global load–deformation behavior, neither for dowel diameters of 12 mm nor for 20 mm, as long as cracking was not decisive. The deformation of the individual dowels was studied by means of a non-contact deformation measurement system. Thus, the crushing deformation, that is, the deformation at the steel plate, and the bending deformation of the dowels could be quantified. In the case of 12 mm dowels, the bending deformation was larger than the crushing deformation, while it was smaller in the case of 20 mm dowels. Moreover, dowels loaded parallel to the grain showed larger bending deformations than dowels loaded perpendicular to the grain. This indicates that the loading of the individual dowels in the connection differs depending on their location.

  • 5.
    Bastani, Alireza
    et al.
    University of Göttingen, Germany.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Militz, Holger
    University of Göttingen, Germany.
    Shear strength of furfurylated, N-methylol melamine and thermally modified wood bonded with three conventional adhesives2017In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 4, p. 236-241Article in journal (Refereed)
    Abstract [en]

    The shear strength of furfurylated, N-methylol melamine (NMM) and thermally modified wood bonded with emulsion polymer isocyanate, polyvinyl acetate (PVAc), and polyurethane (PU) adhesives was examined. Furfurylation and NMM modification of Scots pine had a significant negative effect on the bonding strength with all adhesives irrespective of the treatment intensity. The obtained low-shear strength values were related to the brittle nature of the wood after modifications rather to the failure of the bondline. PVAc showed a better bonding performance with both furfurylated and NMM modified wood while the combination of furfurylated wood and PU gave the highest reduction in bonding strength (47–51%). Shear strength also decreased significantly after thermal modification in both Scots pine (36–56%) and beech (34–48%) with all adhesives. With the exception of thermally modified beech samples bonded with PU, bondline was found to be the weakest link in thermally modified wood as it was revealed by the wood failure surfaces. Bondline thickness and effective penetration of adhesives did not relate to the shear strength of all modified wood materials. The lower shear strength of modified wood could be attributed to other factors, such as the reduced chemical bonding or mechanical interlocking of adhesives, and the reduced strength of brittle modified wood substrate.

  • 6.
    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.

  • 7.
    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.

  • 8.
    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.

  • 9.
    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.

  • 10.
    Blomqvist, Lars
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Sandberg, Dick
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Shape stability of laminated veneer products: an experimental study of the influence on distortion of some material and process parameters2013In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, no 3, p. 198-211Article in journal (Refereed)
    Abstract [en]

    Laminated bending of veneers is a common used and important process for manufacture of components primarily for furniture and interior purposes. According to the use, such products are in general very sensitive to variations in the intended shape, i.e. distortion can be of great problem and more or less destroy the use of the final product. The most critical mode of distortion is twist, but also other changes in shape may be of interest to keep low. The causes to distortion of laminated bended veneer products can be of material (veneer, adhesive and the combination of these), design, processes and climate nature and there is a challenge to know which parameters which are of major importance for distortion, both directly after moulding and when the products are in use.

    In this study, the influence of type of UF-adhesive hardener, i.e. liquid or powder, water content of adhesive, adhesive distribution, variation of moisture content of glued veneers, and fibre orientation of veneers, on twist and position for a 3D-veneer construction (a chair seat shell) has been studied. Distortion, i.e. twist and position, has been determined directly after moulding and after moisture cycling. The moisture cycling was to simulate and accelerate conditions that the shells are subjected in use. The aim of the work is to study how the above mentioned material and process parameters influence the shape stability of the products.

    The results show that the climate, i.e. how a certain level of temperature and relative humidity influence the moisture content of the moulded product, has a clear impact on the distortion of the product in use. An increase in moisture content results in a significant increase in distortion and vice versa. The level to which the moulded products distort during climate variation can be controlled through controlling material, design and process parameter during moulding. Of the studied parameter mentioned above, a deviation in fibre orientation of the veneers in the moulded assembly is the most critical parameter to have under control to minimize distortion. The fibre deviation mainly results in an increase in twist. A high moisture content of a veneer vis-à-vis the rest of the veneers in the assembly before moulding, will result in increased position and twist of the moulded product in use. The difference of moisture content between veneers and the position of veneers with high moisture content in the assembly will influence the level of distortion. Other studied parameter also influences the distortion to a lesser extent and can in these cases be related to the moisture distribution in the mouldings.

  • 11.
    Blomqvist, Lars
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Sandberg, Dick
    Luleå tekniska universitet, Luleå University of Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Influence of veneer orientation on shape stability of plane laminated veneer products2014In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 9, no 4, p. 224-232Article in journal (Refereed)
    Abstract [en]

    One of the most important quality aspects of a laminated veneer product is its shape stability under changing relative humidity (RH). This study aimed to establish an understanding of how the orientation of individual veneers in the laminate, i.e., orientation according to fibre orientation and orientation of the loose (the side with ‘lathe checks’) or tight side of the veneer, affects the shape stability. Three-ply laminates from peeled veneers of beech (Fagus sylvatica L.) were studied. The four types of laminate were the following: loose sides of all veneers in the same direction (cross and parallel centre ply) and loose sides of the outer veneers facing inward (cross and parallel centre ply). Four replicates of each type yielded 16 samples. The samples were exposed to RH cycling at 20% and 85% RH at 20°C, and the shapes of the samples were determined. The shape stability was influenced by the veneer orientation. Laminations with the middle veneer perpendicular to the top and bottom veneer (cross-laminated) showed the best shape stability, especially when the loose sides of the veneers were oriented the same direction. In parallel-laminated veneers, the laminates with opposite directions of the loose sides in the two outermost veneers showed the best shape stability. The major explanation of the behaviour of the laminates is that the loose side expanded more than the tight side from the dry to the humid climate, which was shown by optical 3D deformation analysis (ARAMISTM). After RH cycling, the laminates with cross plies showed visible surface checks only when the tight side was facing outwards.

  • 12.
    Bolmsvik, Åsa
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Linderholt, Andreas
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Damping elastomers for wooden constructions: Dynamic properties2015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 3, p. 245-255Article in journal (Refereed)
    Abstract [en]

    Elastomers are commonly used to decrease the sound transmission between apartments in timber framed houses. Inprevious studies, different types of connections have been evaluated. However, the frequency dependent dynamic propertiesin different directions of a connection including elastomers are not fully investigated yet. Previous studies have actuallyshown that elastomers cause the vibrations to increase in the direction perpendicular to the applied load within the lowfrequency span. The properties of the elastomers are needed in order to model the dynamic behaviour and thereby be ableto predict sound and vibration transmissions in wooden houses in the future. With known properties, the elastomerconnections can be modelled using springs and dashpots. In this study, dynamic experiments have been made on elastomerstrips half embedded. The test setup has been subjected to various loads using an electromagnetic shaker. The responseshave been measured and evaluated using modal analysis. With different loads, non-linear characteristics of the elastomers’behaviour have been obtained. The elastomers have also been tested quasi-statically, to obtain a load-deflection curve.Finally, the estimated properties of the elastomers have been included in an FE model using springs and the analyticalresults are compared with the experimental results.

  • 13.
    Caprolu, Giuseppe
    et al.
    Luleå University of Technology.
    Girhammar, Ulf Arne
    Luleå University of Technology.
    Källsner, Bo
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Analytical models for splitting capacity of bottom rails in partially anchored timber frame shear walls based on fracture mechanics2017In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 3, p. 165-188Article in journal (Refereed)
    Abstract [en]

    Plastic design methods can be used for determining the load-carrying capacity of partially anchored shear walls. For such walls, the leading stud is not fully anchored against uplift and tying down forces are developed in the sheathing-to-framing joints and the bottom rail will be subjected to crosswise bending, leading to possible splitting failure of the rail. In order to use these plastic design methods, a ductile behaviour of the sheathing-to-framing joints must be ensured. In two earlier experimental programmes, the splitting failure capacity of the bottom rail has been studied. Two brittle failure modes occurred during testing: (1) a crack opening from the bottom surface of the bottom rail and (2) a crack opening from the side surface of the bottom rail. In this article, a fracture mechanics approach for the two failure modes is used to evaluate the experimental results. The comparison shows a good agreement between the experimental and analytical results. The failure mode is largely dependent on the distance between the edge of the washer and the loaded edge of the bottom rail. The fracture mechanics models seem to capture the essential behaviour of the splitting modes and to include the decisive parameters.

  • 14.
    Dagbro, Ola
    et al.
    Linnaeus University, The University Administration. Linnéuniversitetet.
    Torniainen, Petteri
    Department of Forest Products, Swedish University of Agricultural Sciences, Uppsala.
    Karlsson, Olov
    Luleå tekniska universitet, Träteknik.
    Morén, Tom
    Luleå tekniska universitet, Träteknik.
    Colour responses from wood, thermally modified in superheated steam and pressurized steam atmospheres2010In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, no 3, p. 211-219Article in journal (Refereed)
    Abstract [en]

    In this study, two different methods were used to produce thermally modified wood. One was carried out in a typical kiln drying chamber using superheated steam (SS) and the other used pressurized steam in an autoclave cylinder (PS). Overall, both processes followed the same principles and the wood was not treated with any chemicals. Two wood species were studied, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Treatments in the autoclave were carried out under pressure using temperatures of 160°C, 170°C and 180°C. Temperatures of 190°C and 212°C were used in treatments in the chamber at normal air pressure. The colour was measured using L*C*H colour space. Results for both species showed that similar L* (lightness) can be reached at lower (20-308C) temperatures using PS compared with SS treatment. The hue angle of PS-treated wood was smaller than that of SS-treated wood. No significant difference in C* (chroma) was detected. The difference in E value between PS- and SS-treated wood was smaller for Norway spruce than for Scots pine. The residual moisture content was about 10% higher in wood treated by the PS process compared with the SS process

  • 15.
    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
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Söderström, Ove
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Moisture content profiles and uptake kinetics in wood cladding materials evaluated by a portable nuclear magnetic resonance spectrometer2011In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, no 3, p. 119-127Article in journal (Refereed)
    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.

  • 16.
    Eliasson, Lars
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Gustafsson, Åsa
    Linnaeus University, Faculty of Business, Economics and Design, Linnaeus School of Business and Economics.
    Quality deficiencies regarding softwood in the pre-fabrication industry for single-family timber houses2012In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, no 1, p. 53-63Article in journal (Refereed)
    Abstract [en]

    The members of the pre-fabricated single-family house industry perceive problems securing the quality of incoming material. Thus the implication is that they need to carry out a quality inspection and adjust the softwood timber as it arrives at their facilities in order to fit the production. Furthermore, due to the intense competition among companies in the pre-fabrication industry, there is a focus on reducing non-value-adding activities such as deficiencies. Consequently, the purpose of this study is to propose a number of propositions regarding quality deficiencies in softwood timber for the pre-fabrication of single-family houses. This study, conducted through interviews based on the theoretical aspects of properties, quality inspection and quality deficiency formulates seven fundamental propositions regarding quality deficiencies in this industry. The main differences among the companies studied are their purchased volume and extent of information and communication technology support in production. This fundamental description of quality deficiencies regarding softwood for the pre-fabrication of single-family houses will enable companies to focus on quality issues with their raw-material suppliers and thereby increase the competitiveness of softwood timber as a construction material in the industry.

  • 17.
    Eliasson, Lars
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Sandberg, Dick
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    A case-study of single-family timber housing in Sweden and its wood material processing costIn: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Article in journal (Refereed)
  • 18.
    Funk, Monika
    et al.
    University of Göttingen, Germany.
    Wimmer, Rupert
    Universität für Bodenkultur Vienna, Austria.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Diotomaceous earth as an inorganic additive to reduce formaldehyde emmissions from particleboards2017In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 2, p. 92-97Article in journal (Refereed)
    Abstract [en]

    The presented research is about the use of a new type of a functional inorganic additive in particleboards, for the purpose of reducing free formaldehyde releases. One-layered particleboards were prepared in the laboratory by mixing industrial wood particles and urea-formaldehyde resin. Natural, abundantly and cheaply available nano-mesoporous diatomaceous earth (DE) was used, without and in combination with urea as a scavenger. Silica quartz sand was also added as a nonporous analogy. Particleboards were pressed at two press factors (9 and 15 s/mm). Formaldehyde release was determined using the rapid 3-hour-flask method (DIN EN 717-3). As a result, DE additions insignificantly reduced bending properties of particleboards. Internal bonding was in part significantly lowered. The particleboard produced with 3% urea loaded on 5% DE prior to application almost halved (–45%) the formaldehyde release. Formaldehyde release was on the average 17% lower when pressed at 15 s/mm instead of 9 s/mm. By loading urea onto the nano-mesoporous structure of DE, an improved scavenging function of urea could be shown.

  • 19.
    Gustafsson, Åsa
    et al.
    Linnaeus University, School of Business and Economics, Department of Management Accounting and Logistics.
    Eliasson, Lars
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Product quality deficiencies in the prefabrication industry for single-family houses2014In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 9, no 1, p. 1-11Article in journal (Refereed)
    Abstract [en]

    In the industry for the prefabrication of single-family houses, previous research had indicated that individual companies have problems in securing the product quality of incoming softwood timber. This implies that they need to carry out a quality inspection and adjust the softwood timber when it arrives at their facility in order to fit their production. Opinions within the industry concerning product quality deficiencies differ with regard to the handling procedures and the percentage of perceived deficiencies. However, there are prefabricators of single-family houses that need to find additional areas for use for their purchased softwood timber, and spend several working hours on softwood timber to meet the quality criteria agreed upon. A previous study by Eliasson and Gustafsson puts forward a number of proposals regarding the quality deficiencies of softwood timber in this context. The present work transforms some of these proposals into hypotheses and aims at describing and understanding what affects the perception of product quality deficiencies. Questionnaires were used to collect data. The paper concludes that the purchase volume is indicated to be related to the volume portion of the deficiency in the product quality and that the level of information- and communication-technology support in production (i.e. the degree of automation) is indicated to be related to the inspection activity point. An extension of the proposed hypotheses concludes that the inspection activity point on arrival and/or on delivery into production also affects how companies do perceive product quality deficiencies. Research regarding what affects product quality deficiencies is lacking in recognizing and knowing what is aligned with the perception of product quality deficiencies; the individual companies will have an opportunity to affect and manage their appearance and thereby enhance the use of softwood timber.

  • 20.
    Jalilzadehazhari, Elaheh
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Material properties of wooden surfaces used in interiors and sensory stimulation2019In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 4, p. 192-200Article in journal (Refereed)
    Abstract [en]

    By covering interiors, such as walls, ceilings and floors, with wooden surfaces, one can change the quality of indoor environments and thereby affect both psychological and physiological responses. Psychological responses refer to individuals’ emotional reactions toward interiors, while physiological responses include changes in the activity of the brain, the autonomic nervous system, the endocrine system, and the immune system. The above-mentioned responses considered in this study are those caused by visual, auditory, olfactory and tactile stimulation from interior wooden surfaces. Although earlier studies have presented valuable information on this subject, questions remain about the material properties of wood which are associated with the stimulation. Specifying the material properties can support architects, designers and engineers who intend to use wood in interiors for improving psychological and physiological responses. A literature study therefore has been conducted to determine (i) the material properties of wood which are associated with sensory stimulation, and (ii) to specify relevant recommendations or requirements which should be fulfilled when covering interiors with wooden surfaces. The results show a lack of knowledge regarding the material properties of wood and the degree in which it affects sensory stimulation.

  • 21.
    Johansson, Jimmy
    University of Kalmar, Department of Technology.
    The Swedish hardwood sawmill industry: Structure present status and development potential2008In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 3, no 3/4, p. 94-101Article in journal (Refereed)
    Abstract [en]

    This study describes the Swedish hardwood sawmill industry with respect to its structure, raw material, production and market conditions in order to seek ways of increasing the competitiveness of the industry. Fifteen sawmills were studied through observations and interviews. The Swedish hardwood sawmill industry creates job opportunities in sparsely populated areas and uses a biological raw material which is important for environmental biological diversity. Any decrease in the use of this material will mean a drop in the incentive for forest owners to cultivate deciduous forests. Today, the hardwood sawmill industry is experiencing problems in securing the supply of raw material of the desired quality, i.e. without knots and discoloured heartwood (red-heart or brown-heart). To increase the competitiveness of the Swedish hardwood sawmill industry, the raw material supply must be secured. Production should be geared towards products demanded by the market, and new markets need to be entered.

  • 22.
    Johansson, Jimmy
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Skog och Trä.
    Gustafsson, Åsa
    Växjö University, Faculty of Humanities and Social Sciences, School of Management and Economics.
    Improved Ecoeffectiveness of interior hardwood products in the house-building industry as a way to promote sustainable forestry2007In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 2, no 1, p. 22-32Article in journal (Refereed)
    Abstract [en]

    Sawn hardwood is required by the market to be homogeneous, even in texture and colour, but the products produced by Swedish hardwood sawmills exhibit a wide variation in characteristics. This makes it difficult for hardwood sawmills to find profitable markets for all their products. By developing new products with other properties for the building industry it may be possible to utilize hardwood more efficiently and increase the prices. This would result in higher ecoeffectiveness (defined as value in relation to environmental impact) of the forest-related business system by giving an incentive to grow deciduous forests, which leads to richer biological diversity. Diversity is fundamental to achieving sustainable forestry. At the same time, other less ecoefficient materials in buildings may be replaced. Exploring the requirements of the customers is essential before developing new products, in order to maximize the value of a product. In this study, the requirements of interior hardwood products in the Swedish house-building industry were studied in interviews and through questionnaires. The most important requirements, ranked higher than price, are delivery on time, shape stability, packaged products, rapid delivery and accurate moisture content. The results make it possible to focus on critical factors to gain market shares for hardwood as an ecoeffective building material.

  • 23.
    Johansson, Jimmy
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Salin, Jarl-Gunnar
    Application of percolation modelling on end-grain water absorption in aspen (Populus tremula L.)2011In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, no 3, p. 112-118Article in journal (Refereed)
  • 24.
    Kozłowski, Marcin
    et al.
    Silesian University of Technology, Poland.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University, Sweden.
    Experimental testing of load-bearing timber–glass composite shear walls and beams2015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 3, p. 276-286Article in journal (Refereed)
    Abstract [en]

    The paper presents results from the experimental testing of load-bearing timber–glass composite shear walls and beams. Shear wall specimens measuring 1200 × 2400 mm2 manufactured with three adhesives of varying stiffness were tested. Twelve specimens with a single 10 mm thick glass pane and one specimen with an additional insulating glass unit were produced. The testing procedures involved various loading conditions: pure vertical load and different combinations of shear and vertical loading. The test results showed that the adhesive had only a minor influence on the buckling load which was the main failure mechanism. 240 mm high and 4800 mm long timber–glass beams manufactured with adhesives of different stiffness were tested. For the webs, two types of glass were used: annealed float and heat-strengthened glass, in both cases 8 mm thick panes were used. In total, 12 beams were tested in four-point bending until failure. Despite the considerable difference in adhesive stiffness, beam bending stiffness was similar. Concerning load-bearing capacity, the beams with heat-strengthened glass were approximately 50% stronger than the beams made using annealed float glass.

  • 25.
    Kumar, Anuj
    et al.
    Natural Resources Institute Finland (Luke), Finland;Czech Technical University in Prague, Czech Republic.
    Ryparovà, Pavla
    Czech Technical University in Prague, Czech Republic.
    Kasal, Bohumil
    Wilhelm-Klauditz-Institut WKI, Germany.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Hajek, Petr
    Czech Technical University in Prague, Czech Republic.
    Resistance of bamboo scrimber against white-rot and brown-rot fungi2018In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Article in journal (Refereed)
    Abstract [en]

    Bamboo scrimber is one of the most emerging structural materials for future building applications andit possesses properties comparable to other natural wood-based engineered materials such as glulam,laminated veneer lumber and cross-laminated timber. The goal of this work was to study the decayresistance of bamboo scrimber against white-rot (Trametes versicolor) and brown-rot fungi (Serpulalacrymans). Bamboo scrimber samples were incubated in petri dishes with the wood-decaying fungiand the weight loss after 12 weeks was measured. The surface morphology of fungal-degradedbamboo scrimber was evaluated using optical microscopy. Based on the percentage weight loss,bamboo scrimber could be classified as highly resistant against bio-deterioration by white andbrown-rot fungi.

  • 26.
    Larsen, Finn
    et al.
    University of Denmark.
    Ormarsson, Sigurdur
    University of Denmark.
    Olesen, John Forbes
    University of Denmark.
    Moisture-driven fracture in solid wood2011In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, no 1-2, p. 49-57Article in journal (Refereed)
    Abstract [en]

    Moisture-induced fractures in solid timber create considerable problems for both building industries and sawmills. Cracks caused by kiln-drying of solid timber are extremely difficult to predict. This paper reports on experiments concerned with methods of reducing cracks in wood and with the cracking behaviour of Norway spruce discs. The spruce was dried from green moisture content down to equilibrium moisture content at 23°C and 64% relative humidity. Moisture-related strains and crack development were measured using a digital image correlation system, Aramis. The moisture gradient in the longitudinal direction had a major influence on crack behaviour and was quite pronounced in discs more than 30 mm thick, but much more limited in discs only 15 mm thick. Although the thicker discs often cracked very early in the drying process, many of these cracks became invisible later on in the drying process, suggesting that sealing the ends of timber logs while in the green moisture state could considerably reduce the development of end-cracks. The initial moisture content and the shrinkage properties of the wood varied markedly from pith to bark. The importance of taking material inhomogeneities into account when modelling crack propagation in solid wood is emphasized. © 2011 Taylor & Francis.

  • 27.
    Lindblad, Fredrik
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Improved transparency in the land allocation process enables an efficient building development activity2019In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Article in journal (Refereed)
    Abstract [en]

    Detailed planning for housing development is the responsibility of the respective municipalities in Sweden. Further, an ambition to develop sustainable building solutions based on wood is combined with each municipality’s building requirements, which increases complexity in the public process. Public actions leading to increased construction of wooden multi-family houses are important for all actors in this process, which is managed by municipalities through the Public Procurement Act or the land allocation process, depending on their development plan and strategy.

    The aim is to shed light on how the land allocation process is currently performed, to improve efficiency and provide transparency and structure between developers and municipalities. The study uses the public procurement process as a conceptual model to structure the various activities in the land allocation process based on the similarities between the two processes. Thereafter, it is applied to the tender-based land allocation process to provide a transparent process for municipalities to follow.

    The results display discrepancies in perception of the land allocation process and the level of competence displayed by municipalities when managing this process. This hinders the development of wooden multi-family houses in Sweden.

  • 28.
    Lindblad, Fredrik
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Structural development of the tender based land allocation process enables an improved public building development activity2019In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Article in journal (Refereed)
    Abstract [en]

    Detailed planning for housing development is the responsibility of the respective municipalities in Sweden. Further, an ambition to develop sustainable building solutions based on wood is combined with each municipality’s building requirements, which increases complexity in the public process. Public actions leading to increased construction of wooden multi-family houses are important for all actors in this process, which is managed by municipalities through the Public Procurement Act or the land allocation process, depending on their development plan and strategy.

    The aim is to shed light on how the land allocation process is currently performed, to improve efficiency and provide transparency and structure between developers and municipalities. The study uses the public procurement process as a conceptual model to structure the various activities in the land allocation process based on the similarities between the two processes. Thereafter, it is applied to the tender-based land allocation process to provide a transparent process for municipalities to follow.

    The results display discrepancies in perception of the land allocation process and the level of competence displayed by municipalities when managing this process. This hinders the development of wooden multi-family houses in Sweden.

  • 29.
    Lykidis, C
    et al.
    Institute of Mediterranean Forest Ecosystems and Forest Products Technology, National Agricultural Research Foundation, Greece.
    Mantanis, G
    Technological Educational Institution (TEI) of Thessaly, Greece.
    Adamopoulos, Stergios
    Technological Educational Institution (TEI) of Thessaly, Greece.
    Kalafata, K
    NanoPhos S.A., Greece.
    Arabatzis, I
    NanoPhos S.A., Greece.
    Effects of nano-sized zinc oxide and zinc borate impregnation on brown-rot resistance of black pine (Pinus nigra L.) wood2013In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, no 4, p. 242-244Article in journal (Refereed)
    Abstract [en]

    In this work, the brown rot resistance of black pine (Pinus nigra L.) wood, pressure-treated in an autoclave with nano-sized zinc borate and zinc oxide dispersions, was investigated. The two formulations based on zinc borate have given encouraging results, indicating fungicide effects of the metal nanoparticles onConiophora puteana. In specific, mean weight losses for P. nigra sapwood exposed to this fungus (one without and one with the addition of a binder) were negligible, that is 0.54% and 0.34%, respectively. On the contrary, the impregnation of pine wood with nano-sized zinc oxide resulted in minimal protection, i.e. 35.9% weight loss. Therefore, nano-sized zinc borate can be utilised in new formulations to impart resistance to wood against the brown rot C. puteana.

  • 30.
    Mantanis, George
    et al.
    Laboratory of Wood Technology, Greece.
    Adamopoulos, Stergios
    Technological Education Institute of Larissa, Greece.
    Rammou, Ekaterina
    Laboratory of Wood Technology, Greece.
    Physical and mechanical properties of Pinus leucodermis wood2010In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, no 1, p. 50-52Article in journal (Refereed)
    Abstract [en]

    The present work reports on the main physical and mechanical properties of Pinus leucodermis mature wood, one of the least studied coniferous species in south-east Europe. Pinus leucodermis heartwood specimens were found to have average density values of 0.73 g cm−3 at equilibrium moisture content of 11.5% and average density of 0.64 g cm−3 under oven-dry conditions. The overall tangential shrinkage was 3.4% and the radial shrinkage was 1.9%. The modulus of rupture was on average 77 N mm−2, while the static modulus of elasticity averaged 7087 N mm−2. The hardness of P. leucodermis heartwood using the modified Janka test was 33.4 N mm−2 in the transverse direction and 48.0 N mm−2 in the longitudinal direction, while its compression strength parallel to grain was approximately 41.6 N mm−2.

  • 31.
    Nilsson, Jonaz
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Kifetew, Girma
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sandberg, Dick
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Shape stability of modified engineering wood product (EWP) subjected to moisture variation2011In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, no 3, p. 132-139Article in journal (Refereed)
  • 32.
    Ormarsson, Sigurdur
    et al.
    Techical University of Denmark.
    Sandberg, Dick
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Numerical simulation of hot-pressed veneer products: moulding, spring-back and distortion2007In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 2, no 3/4, p. 5p. 130-137Article in journal (Refereed)
    Abstract [en]

    Customers demand very high quality of veneered furniture products with regard to surface appearance, shape stability and stiffness. To meet these requirements, it is important to improve the manufacturing process by a better understanding of the thermo-hydro-mechanical behaviour of the individual veneers. During the manufacture of strongly curved products, the veneers are exposed to large membrane and bending deformations and to high pressure in the radial fibre direction. When hot-press forming is used, the veneers are also exposed to a high surface temperature during the pressing time (curing time). These severe conditions can result in plastic deformation perpendicular to the veneer surface as well as mechano-sorptive strains in the curved regions, since the heating can have a significant influence on the moisture distribution. How strong an influence these factors have on the distortion of the veneered product is far from being fully clarified. To study this complex multi-physical problem including temperature, moisture, large deformations for orthotropic materials, surface constraints and progressive glue interaction, a three-dimensional finite element simulation has been performed. In this study, the simulation of deformations and stresses occurring during the manufacture of a curved veneered product (chair seat) of birch wood is described. The results show that heating, pressure and the fibre orientation in the veneers have a significant influence on the distortion of the chair seat.

  • 33.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Haller, Peer
    Institute of Steel and Timber Construction, Technische Universität Dresden, Germany.
    Parviz, Navi
    Wood and Civil Engineering, Bern University of Applied Science, Biel, Switzerland.
    Thermo-hydro and thermo-hydro-mechanical wood processing: an opportunity for future environmentally friendly wood products2013In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, no 1, p. 64-88Article, review/survey (Refereed)
    Abstract [en]

    This state-of-the art report presents the basic concepts of some of the thermo-hydro (TH) and thermo-hydro-mechanical (THM) wood processes that are in use today, i.e. heat treatment, compression of wood in the longitudinal or transverse direction, and wood welding. The reasons for the growing interest in TH and THM techniques are discussed and the development of the different concepts, from first ideas to current status, is briefly presented. The physical and chemical changes that occur in wood during TH and THM processing according to the latest research are also presented. Finally, developments that are close to or already have an industrial application are presented and the challenges for further development of the heat treatment, compression and wood welding processes are discussed.

    The TH processing of wood is based entirely on water and heat, and a THM process incorporates an additional mechanical force. The purpose of wood transformation by a TH or a THM process is to improve the intrinsic wood properties, to acquire a form and functionality desired by engineers without changing its eco-friendly characteristics or hindering its further use in the total material life cycle.

    Only a few of the recently developed techniques, e.g. wood welding and various densification applications, have been industrialized to any great extent. There are many reasons for this relatively low transfer of the research results to a full up-scaled industrial production. Some of them are related to unsolved problems at the laboratory level on small-size samples and others are related to the scaling-up processes in industry. Furthermore, the aging of heated wood leads to deterioration with time, in some cases there is an unpleasant odour, the strength of the wood decreases substantially and the wood becomes more brittle. These are new challenges which need to be resolved by the collaboration of researchers from the different scientific domains of academia, research institutes and industry.

  • 34.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Simulation of the yield of knot-free components from Scots pine (Pinus sylvestris L.): A comparative study of star-sawing and square-sawing2006In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 1, no 3-4, p. 8p. 108-115Article in journal (Refereed)
    Abstract [en]

    The production of knot-free wood is important since the market demands wood without knots for reasons of both appearance and material properties. This work describes a simulation of the removal of knots from star-sawn timber and square-sawn. The efficiency of the two methods is compared in terms of the length of the knot-free components obtained and the volume yield.

    The simulation is based on data for trees and logs taken from The Swedish Stem Bank. These data are then used to simulate the sawmill process in a computer program called the Virtual Sawmill. Data related to the boards obtained are then used in a MATLAB model simulating the cross-cutting of knots.

    Simulated star sawing of logs with a top diameter exceeding 230 mm gave a mean knot-free component length of 417 ±321 mm, while the mean length of knot-free components for simulated square sawing of the same logs was 298 ±122 mm. The volume yield of knot-free components from the two sawing patterns was 91 % for star sawing and 87 % for square sawing. For timber with cross-section dimensions of 38 x 75 mm2, the mean length and yield of knot-free components from simulated star sawing were 451 ±349 mm and 90 % respectively. In simulated square sawing, the corresponding values were 263 ±197 mm and 82 % respectively. This shows that star sawing has a potential for the production of knot-free timber.

  • 35.
    Sandberg, Dick
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Söderström, Ove
    KTH.
    Crack formation due to weathering of radial and tangential sections of pine and spruce2006In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, ISSN 1748-0272, Vol. 1, no 1, p. 9p. 12-20Article in journal (Refereed)
    Abstract [en]

    The development of cracks and changes in appearance have been investigated on radial and tangential sections of pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) after exposure outdoors for 61 months. The degradation of the sections has also been studied at the micro-level.

    The annual ring orientation was the most important factor affecting crack development on weathering. After 61 months of outdoor exposure, the tangential sections of spruce had 1.7–2.2 times greater mean total crack length per area unit than the corresponding radial sections. In pine, the total crack length per area unit on the tangential sections was 2.2–2.6 times greater than that on the radial sections. Tangential and radial sections show the same colour change as a result of weathering.

    Tangential sections have more and deeper cracks than radial surfaces. The cracks on the tangential sections occur frequently in both earlywood and latewood. On radial sections, cracks occur primarily at the annual ring borders, but to a certain extent also in the earlywood.

    Decomposition of the cell wall takes place in both radial and tangential cell walls and cracks tend to follow the fibril orientation in the S2-layer of the cell wall. The radial cell wall of the earlywood has a large number of pits which are degraded at an early stage.

  • 36.
    Schauerte, Tobias
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    7th Forum Wood Building Nordic, hosted at Linnaeus University in Vaxjo, Sweden 27/28 of September 20182019In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 4, p. 191-191Article in journal (Other academic)
  • 37.
    Schauerte, Tobias
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Editorial: Special Issue: Forum Wood Building Nordis 20152015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 3, p. 215-Article in journal (Other academic)
  • 38.
    Stendahl, Matti
    et al.
    Swedish University of Agricultural Sciences, Uppsala.
    Eliasson, Lars
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Integrated production of semi-finished components in sawmills, part II: Management of internal operations.2013In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 9, no 1, p. 12-30Article in journal (Refereed)
    Abstract [en]

    Recently, several Swedish sawmills have taken over production of components from customers in the furniture, joinery and house-manufacturing industries. The purpose of this study was to identify key factors in management of internal operations for sawmills with this strategy. A multiple case study design, based on face-to-face interviews with Swedish sawmill practitioners and on various forms of secondary data, produced comprehensive research information. Starting integrated production of components is a demanding strategy for sawmills. It requires deep knowledge about the customer and qualified skills in advanced further-processing of sawn wood. The complexity of quality management, production planning and cost calculation increases, and investments in processing equipment and customer relations reduce strategic flexibility. The diverging material flow complicates sawmills' possibilities to economize on scale, and they must instead economize on other factors, such as scope, combined operations and internal control. New tools for production follow-up and control, for production planning, for analysis of product profitability and for strategic partnership analysis are requested by practitioners. But, even if new analysis tools would facilitate better analysis and management of operations, the willingness and ability to innovate and learn among the personnel emerges as a key factor for success.

  • 39.
    Stendahl, Matti
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    McCluskey, Denise
    Swedish University of Agricultural Sciences, Sweden.
    Eliasson, Lars
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Integrated production of semi-finished components in sawmills, part I: External interactions2013In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, no 4, p. 253-270Article in journal (Refereed)
    Abstract [en]

    In a changing business landscape, where globalization and new customer requirements create new business opportunities, some Swedish sawmills have taken over the production of components from their industrial customers. In light of the emerging network-centric perspective on business, sawmill managers' perceptions about component customers' operational requirements, customer interaction processes, and their sawmills' offerings are researched and discussed in this article. A multiple case study design, based on face-to-face interviews with Swedish sawmill managers and on various forms of secondary data, produced comprehensive information about sawmills' interaction processes with component purchasing customers. Thematic data coding facilitated the assessment of the research information in relation to the conceptual and empirical findings of previous research. The findings of the study indicate that more process orientation in housing-, joinery-, and furniture-manufacturing implies an opportunity for sawmills to make service-based offerings including not only physical goods, but also administrative services, logistics, and expert advice. The results of the study confirm the network-centric perspective on business where value is created through the interaction between firms. However, noteworthy barriers in the form of process-, culture-, as well as socially related factors at customer firms must be considered.

  • 40.
    Stenudd, Stefan
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Skog och trä.
    The influences of log storage and kiln drying climate on the colour of non-steamed beech (Fagus sylvatica L.) wood.2008In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 3, no 1-2, p. 71-77Article in journal (Refereed)
    Abstract [en]

    Discolouration during the drying of non-steamed beech is a major industrial concern. The generally preferred yellow-white colour can easily develop a reddish or dull grey appearance during drying. In this study, the influences of log storage time and kiln drying climate on the colour of non-steamed sawn beech have been investigated and quantified. Samples 27x87 mm in cross section were dried in laboratory kilns and the average colour, in CIELAB colour space was measured on dry planed surfaces using a photoelectric colorimeter. Log storage for 13 weeks under low-temperature conditions had no visible effect. The reddish discolouration is mainly temperature related while the greyish discolouration is mainly controlled by the equilibrium moisture content (EMC) during the initial drying. Within the investigated climate interval, the EMC was twice as important as temperature for the final colour. Regression models developed show that, as long as the EMC is kept below 15%, a temperature of up to 37 degree Celsius can be allowed without any visually detectable discolouration.

  • 41.
    Sterley, Magdalena
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Gustafsson, Per Johan
    Lund University.
    Shear Fracture Characterisation of Green Glued Polyurethane Wood Adhesive Bonds at Various Moisture and Gluing Conditions2012In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 7, no 2, p. 93-100Article in journal (Refereed)
    Abstract [en]

    The shear fracture properties of green-glued one-component polyurethane (PUR) wood adhesive bonds subjected to kiln drying were investigated. The local shear strength and fracture energy of the wood adhesive bonds were determined from experimentally recorded complete shear stress versus deformation curves of the bond line. A stable test set-up and small specimens that were anti-symmetrically loaded were used in order to get a uniform and pure state of shear stress. Different moisture contents (MCs) and pressing times were investigated. The fracture properties of conventionally dry-glued wood adhesive bonds and of solid wood were used as reference. The results show that the fracture energy of green-glued bonds with PUR adhesive is dependent on the MC of wood and on the pressing time. The same fracture energy and strength can be obtained by green gluing as by dry gluing, but there seems to exist a maximum MC of sapwood, in the range between 78% and 160%, and a minimum pressing time, in the range between 3 h and 48 h, for which it can be achieved. Both dry- and green-glued polyurethane adhesive bonds were more ductile than solid wood.

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