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  • 1.
    Bekhta, Pavlo
    et al.
    Ukranian National Forestry University.
    Sedliacik, Jan
    Technical University in Zvolen.
    Jones, Dennis
    DJ Timber Consultancy Ltd.
    Effect of short-term thermomechanical densification of wood veneers on the properties of birch plywood2018In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 76, no 2, p. 549-562Article in journal (Refereed)
    Abstract [en]

    In this study, the physical and mechanical properties of plywood panels made from pre-compressed birch (Betula verrucosa Ehrh.) veneer were evaluated. Veneer sheets underwent short-term thermo-mechanical (STTM) compression at temperatures of 150 or 180 ⁰C and at pressures of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 or 3.5 MPa for a period of 1 minute before being adhesive applied and pressed into panels using phenol formaldehyde adhesive at 100 g/m2 spread rate; this was one third less than the adhesive spread used for the control panels (150 g/m2). The pressing pressure was 1.0 MPa that was almost half of the pressure used for the control panels (1.8 MPa); and pressing time was 3 min, also half of the pressing time used for the control panels (6 min). The results showed that surface roughness of compressed veneer, water absorption and thickness swelling of plywood panels made from compressed veneer were significantly improved. The shear strength values of plywood panels made from compressed birch veneer even with reduced adhesive spread were higher than those of plywood panels made from un-compressed veneer. The findings in this study indicated that compression of birch veneer would be considered as an alternative to produce more eco-friendly (owing to smaller adhesive spread) value-added material with enhanced properties.

  • 2.
    Berg, Sven
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Turesson, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ekevad, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Huber, Johannes Albert Josef
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Finite element analysis of bending stiffness for cross-laminated timber with varying board width2019In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 6, p. 392-403Article in journal (Refereed)
    Abstract [en]

    ross laminated timber (CLT) is a wood panelling building system that is used in construction, e.g. for floors, walls and beams. Because of the increased use of CLT, it is important to have accurate simulation models. CLT systems are simulated with one-dimensional and two-dimensional (2D) methods because they are fast and deliver practical results. However, because non-edge-glued panels cannot be modelled under 2D, these results may differ from more accurate calculations in three dimensions (3D). In this investigation, CLT panels with different width-to-thickness ratios for the boards have been simulated using the finite element method. The size of the CLT-panels was 3.0 m × 3.9 m and they had three and five laminate layers oriented 0°–90°–0° and 0°–90°–0°–90°–0°. The thicknesses of the boards were 33.33, 40.0, and 46.5 mm. The CLT panel deformation was compared by using a distributed out-of-plane load. Results showed that panels with narrow boards were less stiff than wide boards for the four-sided support setup. The results also showed that 2D models underestimate the displacement when compared to 3D models. By adjusting the stiffness factor k88, the 2D model displacement became more comparable to the 3D model.

  • 3.
    Blomqvist, Lars
    et al.
    Linnӕus University, Department of Building Technology, Växjö, Sweden. RISE, Research Institute of Sweden.
    Berg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Department of Wood Processing and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Distortion in laminated veneer products exposed to relative-humidity variations: Experimental studies and finite-element modelling2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 2, p. 3768-3779Article in journal (Refereed)
    Abstract [en]

    A shortcoming of the laminated bending process is that the product may become distorted after moulding. This study focused on the influence of fibre orientation deviation for individual veneers on the distortion of a moulded shell. The distortion of 90 cross-laminated shells of the same geometrical shape, consisting of seven peeled birch veneers, were studied under relative humidity variation. All the veneers were straight-grained in the longitudinal-tangential plane, but to simulate a deviation in fibre orientation, some of the individual veneers were oriented at an angle of 7° relative to the main orientation of the other veneers in the laminate. A finite element model (FEM) was applied to study the possibility of predicting the results of a practical experiment. The study confirms the well-known fact that deviation in fibre orientation influences shape stability. The results also show how the placement of the abnormal veneer influences the degree of distortion. From this basic knowledge, some improvements in the industrial production were suggested. However, the FE model significantly underestimated the results, according to the empirical experiment, and it did not show full coherence. The survey shows the complexity of modelling the behaviour of laminated veneer products under changing climate conditions and that there is a great need to improve the material and process data to achieve accurate simulations. Examples of such parameters that may lead to distortion are density, annual ring orientation in the cross section of the veneer, the orientation of the loose and tight sides of the veneer, and parameters related to the design of the moulding tool.

  • 4.
    Báder, Mátyás
    et al.
    University of Sopron, Sopron, Hungary.
    Bak, Miklós
    University of Sopron, Sopron, Hungary.
    Németh, Róbert
    University of Sopron, Sopron, Hungary.
    Rademacher, Peter
    Mendel University in Brno, Brno, Czech Republic.
    Rousek, Radim
    Mendel University in Brno, Brno, Czech Republic.
    Horníček, Stanislav
    Mendel University in Brno, Brno, Czech Republic.
    Dömény, Jakub
    Mendel University in Brno, Brno, Czech Republic.
    Klímek, Petr
    Mendel University in Brno, Brno, Czech Republic.
    Kudela, Jozef
    Technical University in Zvolen, Zvolen, Slovakia.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Neyses, Benedikt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kutnar, Andreja
    University of Primorska, Koper, Slovenia; InnoRenew CoE, Izola, Slovenia.
    Wimmer, Rupert
    University of Natural Resources and Life Sciences, Vienna, Austria; Renewable Materials, Tulln an der Donau, Austria.
    Pfriem, Alexander
    Eberswalde University for Sustainable Development, Eberswalde, Germany.
    Wood densification processing for newly engineered materials2018In: Proceedings of the 5th International Conference on Processing Technologies for the Forest and Bio-based Products Industries (PTF BPI 2018), Freising/Münich, September 20-21 / [ed] M. C. Barbu; A. Petutschnigg; E. M. Tudor, Kuchl, 2018, p. 255-263Conference paper (Refereed)
    Abstract [en]

    Wood is a renewable, bio-based material with a mixture of different properties and qualities, used in numerous applications. Beside many species with high wood qualities several species suffer due to a number of disadvantages, where low hardness and abrasive resistance are characteristic for low-density species. This paper presents examples of on-going European research projects and industrial processes mostly related to wood densification methods. Wood densification is a classical thermohydro-mechanical (THM) wood treatment process, through which density is increased by mechanical compression of wood perpendicular to the grain, by impregnation of cell lumens or cell walls with solutions or melted substances (resins, waxes), or by a combination of both. The purpose is to produce newly designed and engineered materials and products with new property profiles, which would potentially find new markets. In general, the THM processes consist of three stages: plasticization of the wood cells, followed by the actualcompression, and finally solidification of the compressed wood in order to prevent elastic spring-back and the moisture-induced set-recovery. The wood densification process refers but is not limited to solid wood and might apply to whole wood pieces, or to local areas within given pieces only. Another THM method is the mechanical compression of wood parallel to the grain, which leads to a product with high flexibility. A European wood research network, represented by the authors of this contribution, has extended experience in many wood modification processes, as demonstrated through ongoing researches and case studies in this paper

  • 5.
    Cool, Julie
    et al.
    University of British Columbia.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Avramidis, Stavros
    University of British Columbia.
    Knot detection in coarse resolution CT images of logs2017In: International Wood Machining Seminar (IWMS-23), 2017Conference paper (Refereed)
    Abstract [en]

    The use of X-ray computed tomography (CT) scanning of logs in sawmill is becoming a reality in the last few years, usually with rather costly and complex machines resembling medical scanners. However, a scanning solution has been developed that is less costly and more robust, and therefore more suited for sawmill needs. The rather coarse data from this machine has not been fully evaluated regarding possibilities to detect internal features such as knots. In this study, a knot detection algorithm developed for medical scanners was applied to images from a coarse resolution scanner, from four different logs of various species, and with different image resolution. The objective was to see if it was possible to detect knots automatically in the images. If so, the aim was to calculate the knot detection rate and the accuracy of detected knot size and position. These numbers were calculated compared to manually measured reference knots. This resulted in a knot detection rate of about 53 % overall, and a well detected knot position, but poorly detected knot size. It is possible to observe a certain difference between species and reconstruction resolution, however the material is too small to draw any definite conclusions. As a preliminary study, it provides input for further investigation on knot detection in coarse resolution X-ray CT images. Future work involves scanning more logs to get more data, and to pinpoint the resolution needed for accurate knot detection using the current algorithm.

  • 6.
    Cool, Julie
    et al.
    University of British Columbia.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Stephen, James D
    Queen’s University.
    Mabee, Warren E
    Queen’s University.
    Avramidis, Stavros
    University of British Columbia.
    Bull, Gary Q
    University of British Columbia.
    An Integrated Forest Products Cluster for Off-Grid Lumber Production Using Biomass CHP in Remote Indigenous Communities2017Conference paper (Refereed)
  • 7.
    Couceiro, José
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    X-ray computed tomography to study moisture distribution in wood2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    X-ray computed tomography (CT) has been used as an analysing tool for different features in wood research since the beginning of the1980s, but it can also be used to study wood-water interactions in different ways, such as by determining wood moisture content (MC). The determination of wood MC with CT requires two CT images: one at the unknown moisture distribution and a second one at a known reference MC level, usually at oven-dry condition. The two scans are then compared, and the MC is calculated based on the differences between the images. If the goal is to determine the MC in local regions within the wood volume, e.g. when studying moisture gradients in wood drying, wood shrinkage must be taken into account during the data processing of the images. The anisotropy of wood shrinkage creates an obstacle, however, since the shrinkage is not uniform throughout the wood specimen. The technique is thus limited in two ways: it cannot measure MC in local regions and it cannot do it in real time.

    The objective of this thesis was to study methods to overcome these two limitations. The work explores up to three different methods to estimate local MC from CT images in real time. The first method determines shrinkage for each pixel using digital image correlation (DIC) and is embedded in a broader method to estimate the MC, which verified against a reference. It involves several steps in different pieces of software, making it time-consuming and creating many sources of possible experimental errors. The determination of shrinkage within this method is further explored to enable the implementation of all steps in a unique piece of software. It is shown that it is possible to calculate MC through this method with a root mean square error of prediction of 1.4 percentage points for MC between 6 and 25%.

    The second method studied succeeds in determining the MC distribution in research applied to wood drying, but the calculation of shrinkage differs from the previous method: instead of calculating shrinkage in the radial and tangential directions, it does so by using the displacement information generated from the spatial alignment of the CT images. Results show that the algorithm can provide consistent data of internal MC distribution of wood at the pixel level that entail continuing researching wood drying processes with an improvement in the accuracy of the MC determination. It represents an improvement regarding the first method because the calculation is fast and highly automatized in a single piece of software.

    The third method studied is the application of dual energy CT (DECT) to moisture. DECT would provide means for MC calculation at the pixel level and, potentially, in real time, which would mean an important breakthrough in wood drying research. Previous research shows promising results, but its implementation in medical CT, the tool used throughout this work, has shown poor predicting ability. Nevertheless, further research is encouraged.

    The work done in this thesis proves that it is possible to measure local distribution of MC in wood using CT with accuracy and precision. It also shows that further research could potentially provide a means for MC estimation in real time.

  • 8.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Dual-energy X-ray absorptiometry for measuring moisture content in wood – Is it possible?2019In: Proceedings of the 21st International Nondestructive Testing and Evaluation of Wood Symposium, Freiburg, Baden-Württemberg, Germany, September 24–27, United States Department of Agriculture , 2019, p. 292-292Conference paper (Refereed)
  • 9.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lindgren, Owe
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Estimation of miosture content in wood using dual x-ray energies in a medical CT-scanner2016In: Process Technologies for the Forest & Biobased Products Industries: PTF BPI 2016, 2016, p. 22-Conference paper (Other academic)
  • 10.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lindgren, Owe
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Department of Ocean Operations and Civil Engineering, Norwegian University of Science and Technology (NTNU), Ålesund, Norway.
    Söderström, Ove
    c Professor Emeritus of Building Materials, Stockholm, Sweden.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Real-time wood moisture-content determination using dual-energy X-ray computed tomography scanning2019In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 6, p. 437-444Article in journal (Refereed)
    Abstract [en]

    The estimation of the pixel-wise distribution of the moisture content (MC) in wood using X-ray computed tomography (CT) requires two scans of the same wood specimen at different MCs, one of which is known. Image-processing algorithms are needed to compensate for the anisotropic distortion that wood undergoes as it dries. An alternative technique based on dual-energy CT (DECT) to determine MC in wood has been suggested by several authors. The purpose of the present study was to evaluate the hypothesis that DECT can be used for the determination of MC in real time. A method based on the use of the quotient between the linear attenuation coefficients (μ) at different acceleration voltages (the so-called quotient method) was used. A statistical model was created to estimate the MC in solid sapwood of Scots pine, Norway spruce and brittle willow. The results show a regression model with R2 > 0.97 that can predict the MC in these species with a RMSE of prediction of 0.07, 0.04 and 0.11 (MC in decimal format) respectively and at MC levels ranging from the green to the totally dry condition. Individual measurements of MC show an uncertainty of up to ±0.4. It is concluded that under the conditions prevailing in this study, and in studies referred to in this paper, it is not possible to measure MC with DECT.

  • 11.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Neyses, Benedikt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    In-situ moisture content and density measurements in surface densified wood using dual X-ray absorptiometry in medical CT-scanning2016In: BIOCOMP 2016: The 13th Pacific Rim Bio-Based Composites Symposium, Bio-based composites for a sustainable future., Concepción: University of Concepción , 2016, Vol. 2, p. 92-, article id NA01Conference paper (Refereed)
  • 12.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The use of X-ray computed tomography in bio-composite research2016In: BIOCOMP 2016: The 13th Pacific Rim Bio-Based Composites Symposium : Bio-based composites for a sustainable future,, Conceptión: University of Concepción , 2016, p. 42-45Conference paper (Refereed)
    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.

  • 13.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Norwegian University of Science and Technology (NTNU), Department of ICT and Natural Sciences, Norway.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    CT scanning of capillary phenomena in bio-based materials2017In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, no 4, p. 181-187Article in journal (Refereed)
    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.

  • 14.
    Cristescu, Carmen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Markers of quality in self-bonded beech boards2017Conference paper (Refereed)
    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.

  • 15.
    Ekatarina, Siderova
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Composition of monosaccharides in aqueous extracts of thermally modified wood.2018In: ECWM9 - The 9th European Conference on Wood Modification / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz, Brigitte Junge and Jos Gootjes, Wageningen: SHR Wageningen, The Netherlands , 2018, p. 575-580Conference paper (Refereed)
  • 16.
    Ekevad, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Huber, Johannes A.J.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jacobsson, Peter
    Martinsons Träbroar AB.
    Mechanics of stress-laminated timber bridges with butt end joints2017Conference paper (Refereed)
    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.

  • 17.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Using a Gaussian filter to reduce the effect of positioning errors when optimizing sawing of CT scanned Scots pine and Norway spruce logs2017In: International Wood Machining Seminar (IWMS-23), 2017Conference paper (Refereed)
    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.

  • 18.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Factors Affecting Volume Yield in a Forestry-Wood Value Chain: A Simulation Study Based on CT Scanning2017In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, no 4, p. 540-548Article in journal (Refereed)
    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.

  • 19.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The Use of CT-Scanning Technology in Wood Value-Chain Research and in Wood Industry: A State of The Art2017In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, no 4, p. 533-539Article in journal (Refereed)
    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.

  • 20.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Brännström, Mattias
    Technical solutions to increase competitiveness of cross-laminated timber from the Nordic countries: an overview2018Conference paper (Refereed)
  • 21.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cool, Julie
    University of British Columbia.
    Avramidis, Stavros
    University of British Columbia.
    Knot detection in computed tomography images of partially dried Jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) logs2017In: International Wood Machining Seminar (IWMS-23), 2017Conference paper (Refereed)
    Abstract [en]

    X-ray computed tomography (CT) of logs means possibilities for optimizing breakdown in sawmills. This depends on accurate detection of knots to assess internal quality. However, as logs are stored in the log yard they dry to a certain extent, and this drying affects the density variation in the log, and therefore the X-ray images. For this reason, it is hypothetically difficult to detect log features in partially dried logs using X-ray CT. The objective of this research was to investigate the effect of drying on knot detection in Jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) logs from New Brunswick, Canada. An automatic knot detection algorithm was compared to manual measurements for this purpose, and the results show that knot detection was clearly affected by partial drying. Because dried heartwood and sapwood have similar densities, the algorithm had difficulties detecting the heartwood-sapwood border. Based on how well the heartwood-sapwood border was detected, it was statistically possible to sort logs into two groups: 1) Low knot detection rate, and 2) High knot detection rate. In that way, a decision can be made whether or not to trust the knot models obtained from CT scanning. Therefore, logs that are partially dried out and fall in the low knot detection rate should be handled cautiously because the optimization results based on CT knot detection cannot be fully trusted. Sawing of these logs could be optimized using only their outer shape, ignoring internal quality. Similarly, only logs having a regular heartwood shape should be used when scanning logs for research purposes or in databases of CT scanned logs. Finally, a larger knot detection rate was obtained for Jack pine. This could have been facilitated by the fact that pine trees usually have larger but less numerous knots than spruce trees.

  • 22.
    Gaff, Milan
    et al.
    Czech University of Life Sciences Prague (CULS).
    Babiak, Marián
    Czech University of Life Sciences Prague (CULS).
    Kačík, František
    Czech University of Life Sciences Prague (CULS), Technical University in Zvolen.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Turčan, Marek
    Czech University of Life Sciences Prague (CULS).
    Hanzlíka, Peter
    Czech University of Life Sciences Prague (CULS).
    Vondrová, Veronika
    Czech University of Life Sciences Prague (CULS).
    Plasticity properties of thermally modified timber in bending: the effect of chemical changes during modification of European oak and Norway spruce.2019In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 165, p. 613-625Article in journal (Refereed)
    Abstract [en]

    The plasticity of thermally modified European oak (Quercus robur L.) and f thermally modified Norway spruce (Picea abies Karst. (L.)) timber was evaluated in bending, and the plastic properties were related to the changes in chemical composition of the wood after modification. The objective was to gain new knowledge about the properties of materials in the plastic region of the force-deformation diagram in bending. A new software was developed (MATESS) and used to identify important characteristics of the material. This software eliminates shortcomings in current standards, such as simplifications in the evaluation of data when sufficiently sensitive measuring equipment is not available. The characteristics studied were: modulus of rupture (MOR), plastic potential (PP) chord modulus (CHM), the moduli of plasticity (EE), and the moduli of plasticity (EMV, EP). Extractives, lignin, cellulose, holocellulose, and hemicelluloses were analysed chemically to reveal the patterns that occur during the loading of the specimens. Thermal modification has different effects on the mechanical properties of oak and spruce, especially on CHM, EMV and EP, due to their different contents and structures of their chemical components. A strong correlation (r > 0.90) between hemicellulose content and MOR and Pp values was found for both species. The coefficients of determination indicated a very low dependence (r2 < 0.1) of MOR, PP, CHM, EE, EMV and EP, on the average density.

  • 23.
    Garskaite, Edita
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Stankeviciute, Zivile
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Aivaras, Kareiva
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Surface hardness and flammability of Na2SiO3 and nano-TiO2 reinforced wood composites2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 48, p. 27973-27986Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to explore an effect of the combined inorganic materials on the wood hardness and flame-retardancy properties in a concept of sustainable material management. Herein, the reinforcement of Scots pine (Pinus sylvestris L.) sapwood with sodium silicate and TiO2 nanoparticles via vacuum-pressure technique is reported. Pyrolysis of modified wood was studied by TG-FTIR analysis; the results showed that maximum weight loss for the modified wood was obtained at 40–50 °C lower temperatures compared to the reference untreated wood. The Gram–Schmidt profiles and spectra extracted at maxima absorption from Gram–Schmidt plots indicated chemical changes in wood–inorganic composites. SEM/EDS analysis revealed the presence of Na–O–Si solid gel within the wood-cell lumen and showed that TiO2 was homogeneously distributed within the amorphous Na–O–Si glass-forming phase to form a thin surface coating. EDS mapping further revealed the higher diffusivity of sodium into the cell wall compared to the silicon compound. The presence of amorphous sodium silicate and nano-TiO2 was additionally confirmed by XRD analysis. FTIR spectra confirmed the chemical changes in Scots pine sapwood induced by alkalization. Brinell hardness test showed that the hardness of the modified wood increased with the highest value (44% increase in hardness) obtained for 10% Na2SiO3–nTiO2 modified wood. The results showed good correlation between TG and flammability test; limiting oxygen index (LOI) values for the wood–inorganic composites increased by 9–14% compared to the untreated wood.

  • 24.
    Han, Lei
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Reduction of Set-recovery of Surface densified Scots Pine by Furfuryl Alcohol2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

     For wood products such as flooring and worktop, only one surface is normally exposed in their use, and the mechanical properties like hardness and wearing resistance of that surface is then important. Since mechanical properties are strongly related to the density, surface densification, i.e. transverse compression of the wood cells beneath the surface of a piece of wood with the aim to increase the density of that region, may be a method for improving hardness and wearing resistance when low-density species are used for such products. The set-recovery, i.e. the moisture-induced swelling of the densified wood cells back to their original shape, is the main obstacle in the use of densified wood products. Although there are several methods reported in literature, such as post heat-treatment, that can almost eliminate the set-recovery, but such methods are either time consuming or difficult to implement into an industrial continuous process which may do densification competitive to techniques or materials that can achieve at least the same hardness.

        In the present study, furfuryl alcohol was used as pre-treatment to fix the set-recovery of surface-densified Scots pine sapwood. The main effect and interactive influence of four process parameter (impregnation time, press temperature, press time and compression ratio) on set-recovery and Brinell hardness after two wet-dry cycles were studied by a two-level full factorial design of experiments. The characterizing variables of the density profile after the surface densification and set-recovery test were carried out as a supplementary tool to learn the mechanism of this two-step modification process. According to the result, the surface densified wood with furfuryl alcohol pre-treatment can retain their dimension and keep hardness at a very high level after two wet-dry cycles. The set-recovery and hardens after two wet-dry cycles were about 20 % and 30 N/mm2, respectively. The Pearson correlation analysis shows that the correlation coefficients between set-recovery with impregnation time, press temperature, press temperature, compression ratio were -0.35, -0.52, -0.37, and 0.16, respectively. That means that for the specimens with furfuryl alcohol pre-treatment, the higher press temperature can reduce the set-recovery significantly. The longer press time and impregnation time can also reduce the set-recovery in some extent, but the influence was  low. As expected, the hardness improvement was retained with low set-recovery. The lowest set-recovery value was 14% with the corresponding hardness of 41 N/mm2 was achieved by specimens processed with 120 minutes of impregnation, 10% compression ratio, 210℃ pressing temperature, and 15 minutes of pressing time. With 20 minutes of impregnation time, 10% compression ratio, 210℃ pressing temperature, and 5 minutes of pressing time, the sample still owns twofold hardness after the set-recovery test.

  • 25. Han, Lei
    et al.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Reducing the set-recovery of surface-densified Scots Pine by furfuryl alcohol modification2019In: Proceedings of the 62nd International Convention of Society of Wood Science and Technology, Tenaya Lodge, Yosemite, California, USA, October 20-25: Convention Theme: Renewable Materials and the Wood-based Bioeconomy / [ed] LeVan-Green, S., SWST, Society of Wood Science and Technology , 2019, p. 200-Conference paper (Refereed)
  • 26.
    Huber, Johannes Albert Josef
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ekevad, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Girhammar, Ulf Arne
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Review of Robustness in Timber Buildings2017Conference paper (Refereed)
    Abstract [en]

    Timber buildings today aim for taller and larger dimensions to accommodate increased numbers of occupants.  In tall buildings, more human lives are at risk if large portions of the structure collapse progressively during catastrophic failure events. To safeguard timber structures from disproportionate collapse due to localised failures, the aspect of robustness in particular needs to be considered. In the literature about building structures the term robustness seems to be contemplated in diverse ways. Several possible approaches to define and analyse this property can be found. However, certain consensus as to what characterises a robust structure seems to exist. A review of the concept of robustness for building structures in general and timber structures in specific is presented in this paper. Certain commonly applied terminology and definitions in the context of robustness are analysed. In the literature, risk-based, reliability-based and performance-based concepts for robustness appear to be established. The first two concepts are briefly summarised. The performance-based concept is treated in greater detail to highlight different procedures of deterministic robustness analyses. Common general characteristics of robust buildings which seem to be agreed upon are summarised. Robustness provisions for timber buildings in specific are described and compared to provisions in other building materials such as steel and concrete. The development of alternate load paths during local failure seems to play an essential role in preventing progressive collapse in buildings. The literature about robustness seems to be comprehensive concerning general considerations and concerning structures built in concrete or steel but appears to be rather limited in regards to timber structures. Evaluations of robustness in timber structures seem to be focused on risk-based and reliability-based concepts in literature.

  • 27.
    Huber, Johannes Albert Josef
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ekevad, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Girhammar, Ulf Arne
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Berg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials. Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Simulation of Alternative Load Paths After a Wall Removal in a Platform-Framed Cross-Laminated Timber Building2019In: CompWood 2019 Book of Abstracts / [ed] Tomas K. Bader, Josef Füssl, Anders Olsson, 2019Conference paper (Refereed)
    Abstract [en]

    An increasing number of multi-storey timber buildings use cross-laminated timber (CLT) for their bearing structure. Platform-framed CLT buildings consist of vertical repetitions of floors resting upon one-storey tall walls, squeezing-in the floor panels between the walls. Tall buildings need to be structurally robust because many lives would be at stake in case of a disproportionate collapse. Robustness is the ability of a system to survive the loss of components. For collapse resistance, it poses the last line of defence, after an unforeseen exposure (e.g. accident, terrorism) has already occurred and after the exposed components could not resist failure. A robust building offers alternative load paths (ALPs) which come into action when a part of the bearing structure has been removed [1].

    Many alternative load path analyses (ALPA) have been conducted for tall concrete and steel buildings using the finite element method (FEM), but for timber, ALPA are still scarce. ALPs depend on the behaviour of the connections after a loss [1]. Studies on timber so far have accounted for connections in a simplified manner by lumping their aggregate behaviour into single points. Our goal is to elicit the ALPs after a wall removal in a platform-framed CLT building, study their development and quantify their capacity, to determine whether they can prevent a collapse.

    We investigated a corner bay of an 8-storey platform-framed CLT building (see Figure 1) and removed a wall at the bottom storey. We studied the ALPs of each storey by pushing down the walls above the gap in a non-linear quasi-static analysis in the FE software Abaqus. We accounted for contact and friction, considered plastic timber crushing, and accounted for brittle cracking in the panels. We modelled single fasteners with connector elements which simulated the elastic, plastic, damage and rupture behaviour. We recorded the force-displacement curves, i.e. pushdown curves, for each storey and used them to conduct a dynamic analysis of the entire bay in a simplified model, as suggested by [2].

    The results show that the structure could engage the following ALPs after a wall removal: I) arching action in the outer floor panels, II) arching action of the walls, III) quasi-catenary action in the floor panels, and IV) hanging action from the roof panels. The ALPs were limited by various parameters, but they sufficed to resist a collapse of the bay. We observed that the inter-storey stiffness influenced the load-sharing among storeys, which affected the structural robustness. In the compressed connections, friction, and not the fasteners, transferred most of the horizontal loads. Future research should test the squeezed-in platform joint experimentally, to quantify its capacity for transverse shear loads. We also advise to assess the inter-storey stiffness to estimate the capacity for load-sharing among storeys.

  • 28.
    Johansson, Marie
    RISE.
    Olsson, Jörgen
    RISE.
    Ylmén, Peter
    RISE.
    Nord, Tomas
    Linköpings Universitet.
    Dorn, Michael
    Linneuniversitet.
    Frühwald Hansson, Eva
    Lunds Universitet.
    Serrano, Erik
    Lund Universitet.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jonsson, Gustav
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Brännström, Mattias
    Renewinn.
    Slutrapport: Framtidens biobaserade byggande och boende.2019Report (Other academic)
  • 29.
    Jones, Dennis
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    A review of wood modification across Europé as part of COST FP14072019In: Timber 2019, Wood Technology Society, The Institute of Materials, Minerals and Mining, London , 2019, p. 107-112Conference paper (Refereed)
  • 30.
    Jones, Dennis
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wood modification in Sweden2018In: Procedings of COST Action FP1407 WG1 and WG4 meeting.: Wood modification in Europe : processes, products, applications / [ed] Goli G and Todaro L., Florence, 2018Conference paper (Other academic)
  • 31.
    Jones, Dennis
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kutnar, Andreja
    University of Primorska, Andrej Marušič Institute, Muzejski trg 2; SI-6000 Koper, Slovenia.
    A review of wood modification across Europe as part of COST FP14072018In: Proceedings of ECWM9 - The 9th European Conference on Wood Modification / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz, Brigitte Junge and Jos Gootjes, Arnhem: SHR B.V. Nieuwe Kanaal 9b 6709 PA Wageningen , 2018, p. 24-31Conference paper (Refereed)
  • 32.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Elustondo, Diego
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Thermally modified wood treated with methacrylate2018In: Proceedings IRG Annual Meeting IRG49 Scientific Conference on Wood Protection Sandton, Johannesburg, South Africa 29 April-3 May, 2018Conference paper (Refereed)
    Abstract [en]

    Thermally modified timber (TMT)from Scots pine sapwood similar to Thermo-D quality was impregnated with methacrylate resin by the hot-and-cold method and subsequently cured at elevated temperatures. The results showedthat methacrylate resin could be used to reduce colouring of painted TMT wood during accelerated weathering probably by hindering the migration of extractives. The resin itself did not reduce greying of the unpainted wood. Hardness was only slightly improved by treatment with the resin probably due to a higher density of the material. Formation of blisters occurred but wasreduced by treatment with the resin. Resistance to mould growth by a mixture of Aureobasidium pullulans, Cladosporium cladosporioides, Aspergillus versicolor, Penicillium purpurogenumwas performed by applying EN-15457:2014. Treatment with methacrylic resin hindered the colonisation of the three last mouldfungi.

  • 33.
    Kim, Injeong
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wood modification with maleic anhydride and sodium hypophosphite2019In: Proceedings of the 20th International Symposium on Wood, Fiber and Pulping Chemistry, ISWFPC20, September 9-11, 2019, Tokyo, Japan, 4 pp., Tokyo: The University of Tokyo , 2019, p. 1-4Conference paper (Refereed)
  • 34.
    Kim, Injeong
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Maleic anhydride and sodium hypophosphite as a potential wood modification system2019In: Proceedings of the 15th Annual Meeting of the Northern European Network for Wood Science and Engineering - WSE2019,  Lund, Sweden, October  9-10, pp. 28-30 / [ed] Fredriksson M (Ed.), Lund: Lund University Open Access, 2019, p. 28-30Conference paper (Refereed)
  • 35.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Haviarova, Eva
    Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Architects´ perception of modified wood: a parallel study in selected countries in Europe and selected regions in USA2017In: COST Action FP1407 3rd Conference: Wood modification research & applications / [ed] Tondi G, Posavčevič M, Kutnar A, Wimmer R., Salzburg, Kuchl, 2017, p. 151-152Conference paper (Refereed)
  • 36.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Haviarova, Eva
    Purdue University.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Architects perception of modified wood: a parallel study in selected countries of Europe2018In: ECWM9 - The 9th European Conference on Wood Modification. / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz, Brigitte Junge and Jos Gootjes, Wageningen: SHR Wageningen, The Netherlands , 2018, p. 82-90Conference paper (Refereed)
  • 37.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Haviarova, Eva
    Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN, USA.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Collaborative housing for elderly: clever co-living concepts2018In: COST Action CA 16121 “From sharing to caring”: International interdisciplinary Seminar Socio-technical aspects of the circular and colaborative economy University Rovira i Virgili, Tarragona, 16th March, 2018, p. 51-54Conference paper (Refereed)
  • 38.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Lähtinen, Katja
    University of Vaasa, Faculty of Business Studies, Department of Marketing, Finland.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Initiatives Supporting Timber Constructions in Finland, Slovenia and Sweden.2017Conference paper (Other academic)
    Abstract [en]

    Presented at the IUFRO 2017 Division 5 Conference "Forest Sector Innovations for a Greener Future", Vancouver, BC, June 12-16, 2017, 18p. Initiatives Supporting Timber Constructions in Finland, Slovenia and SwedenManja KITEK KUZMAN, Katja LÄHTINEN, Dick SANDBERGUniversity of Ljubljana, Biotechnical Faculty, Department of Wood Science and Technology, Slovenia manja.kuzman@bf.uni-lj.siUniversity of Vaasa, Faculty of Business Studies, Department of Marketing, The University Consortium of Seinäjoki, Finland klahtine@uwasa.fiLuleå University of Technology, Wood Science and Engineering, Swedendick.sandberg@ltu.seAbstractFinland, Slovenia and Sweden are the three most forested countries in the European Union. While Finland and Sweden have a long tradition of building with wood, most housing in Slovenia were made with brick and stone. In Finland, knowledge of wood, an age-old building material, is actively preserved and enhanced. New wood buildings gain a contemporary twist, and are a significant part of the building stock in Finland. Swedish long tradition with timber construction is going from strength to strength thanks to the development of advanced, modern day timber structures. Sweden’s national building code has allowed the construction of multi-storey timber housing since the mid1990s. Builders and architects know that timber is not only an economical building material but that it has the added bonus of being climate friendly. Though few in number, most Slovenian timber buildings combine contemporary styling with energy efficiency measures that bring them close to passive house standards. Slovenia’s construction industry is widely recognized as advanced in the field of low energy buildings. As energy-efficient building methods gain importance, timber passive houses can play an increasingly important role in the future.In this paper, the Finnish, Slovenian and Swedish initiatives and legalization supporting timber constructions will be presented in relation to current European regulations with an emphasis on the use of wood as a sustainable architectural construction material for the future

  • 39.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Current trends and future directions for multi-storey timber buildings2017In: Macedonian Association of Structural Engineers ( MASE) 17th International Symposium, 4-7 Sept. 2017, Ohrid, Macedonia: Book of abstracts, Ohrid: Macedonian Association of Structural Engineers , 2017, p. 205-215Conference paper (Refereed)
  • 40.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Development of multi-storey buildings and future trends2017Conference paper (Refereed)
    Abstract [en]

    Extensive research has shown that material-neutral building regulations are preferable and, for over a decade, function-based regulations have been common in many European countries, and this have contributed to an increase in the construction of multi-storey timber buildings. As one example, in the Scandinavia the development since mid-1990th of multi-storey timber buildings can be described as a success story, but there is also many other countries that have a positive development in timber construction. There is a great market potential for the use of wood in all types of buildings employing a combination of digital design and CNC (computer numerical control) processing. The construction engineers know how to make use of the digital tools; they have geometric imagination capabilities and construction know-how while the architects have ambitious ideas for building extraordinary projects. Digital design and production using CAE (computer-aided engineering), CAD (computer-aided design) and CAM (computer-aided manufacturing) have allowed timber construction to forge ahead into new dimensions of design. Innovative connections, modern wood-based materials and cutting-edge CNC milling offer entirely new possibilities and shape wood into almost any conceivable form. This paper gives an overview of the development of multi-storey timber building with a special focus on future trends in combination of digital design as flexible planning and design tools in combination with CNC processing to design and build extraordinary projects. Keywords: A rchitecture; timber construction; digital design; wood processing

  • 41.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Engineered wood products in contemporary architecture.2018In: COST Action FP1407 Final Conference: – Living with modified wood. / [ed] Milic´, G., Todorovc´, N., Palilja T. & Kutnar A., Belgrade, 2018, p. 68-69Conference paper (Refereed)
  • 42.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Produits d’Ingénierie en Bois pour l’Architecture Contemporaine – Cas d´étude.2018 (ed. 1000)Book (Refereed)
    Abstract [fr]

    Ce livre explore et illustre les utilisations de différents produits de bois d'ingénierie (PBI) contemporains et introduit de nouveaux matériaux à base de bois. Chaque page décrit un PBI spécifique illustré par des images éloquentes montrant différentes applications des PBI dans l'architecture et la construction intérieure et extérieure des bâtiments.

    Aucun matériau n'a été jadis aussi présent dans notre quotidien que le bois sous ses différentes formes. Les PBI présentent le lien entre la science du bois, l'ingénierie structurelle, l'architecture et la conception Le travail présenté est issu de la collaboration interdisciplinaire et des expériences diverses de trois chercheurs en bois de Slovénie, Suède et France, avec des compétences (i) en ingénierie du bois avec une expérience et une connaissance des besoins technologiques, (ii) en architecture avec une connaissance approfondie des besoins liés à la culture, (iii) en Génie civil et sciences du bois orientées vers l'environnement et la foresterie.

    Le but du livre est de promouvoir l'utilisation des PBI basées sur une technologie de haut niveau et un savoir-faire technique qui nécessite une réflexion créative, une vision globale et des points de vue philosophiques. En définitive, nous allons accroitre les connaissances inhérentes à l'utilisation du bois, atteindre l'excellence dans la formation et la conception des produits à base de bois. L'ouvrage sera utile aux concepteurs, aux architectes et aux experts dans leurs efforts continus pour une meilleure utilisation du bois dans la conception et la planification architecturale contemporaine. A titre d’exemple, une étude comparative de perception qu'ont les architectes français et gabonais sur les produits de bois d'ingénierie est proposée afin de donner plus d'informations à l'architecte et à l'ingénieur civil sur ces produits.

  • 43.
    Kitek Kuzman, Manja
    et al.
    University of Ljubljana, Wood Science and Technology.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Haviarova, Eva
    Purdue University.
    Architects´perception of EWPs and modified wood in contemporary timber architecture2018In: Proceedings of WCTE 2018, Republic of Korea: National Institute of Forest Science , 2018, p. 1-6Conference paper (Refereed)
  • 44.
    Kroupa, Michal
    et al.
    CULS, Prague University of Life Sciences.
    Milan, Gaff
    CULS, Prague University of Life Sciences.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Effects of thermal modification on bending properties and chemical structure of Iroko and Padauk.2018In: Proceedings of ECWM9 - The 9th European Conference on Wood Modification / [ed] Jos Creemers, Thomas Houben, Bôke Tjeerdsma, Holger Militz, Brigitte Junge and Jos Gootjes, Wageningen: SHR Wageningen, The Netherlands , 2018, p. 155-161Conference paper (Refereed)
  • 45.
    Lin, Chia-Feng
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Mantanis, George I.
    University of Thessaly, Dept. of Forestry, Wood Sciences and Design, Lab of Wood Science & Technology.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Fire performance and leach resistance of pine wood impregnated with guanyl-urea phosphate (GUP)/boric acid (BA) and melamine-formaldehyde (MF) resin2019In: Proceedings of the 15th Annual Meeting of the Northern European Network for Wood Science and Engineering - WSE2019,  Lund, Sweden, October  9-10 / [ed] Fredriksson M., Lund: Lund University Open Access, 2019, p. 147-149Conference paper (Refereed)
  • 46.
    Markström, Emillia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Bystedt, Anders
    RISWE Research Institutes of Sweden.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Prospects for an increased use of bio-based building materials in Sweden2017Conference paper (Refereed)
  • 47.
    Markström, Emillia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kitek Kuzman, Manja
    University of Ljubljana, Wood Science and Technology.
    Bystedt, Anders
    RISE Research Institutes of Sweden, RISE Bioeconomy.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Swedish architects view of engineered wood products in buildings2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 181, p. 33-41Article in journal (Refereed)
    Abstract [en]

    From a climate perspective, it could be advantageous to increase the use of wood products in buildings, but the use of sawn timber and engineered wood products (EWPs) in multi-storey buildings above two floors are a relatively new business (in Sweden since 1995) and there is a risk that wood as construction material is met with low awareness and high uncertainty by the construction sector. The purpose of this study was twofold: 1) to learn Swedish architects' views of using EWPs in buildings, and 2) to identify parameters that positively influence the likelihood that EWPs will be selected to a greater extent and the relative importance of those parameters.

    A survey was sent out to Swedish architects and 67 answers were received. The result indicates that architects in Sweden have a positive attitude towards EWPs in general and that the majority think that they will probably increase their use of these materials. Low impact on the environment, aesthetic appeal, and fast construction were the most common reasons stated for selecting EWPs. The Swedish architects have in general a moderate impact on the selection of materials, and the most common reason for not selecting EWPs was that other decision makers involved in the building projects prefer other materials. A lack of knowledge and information as well as uncertainties regarding the quality over time were other common reasons for not selecting EWPs.

    It was found that architects who had participated in building projects where EWPs had been chosen due to their low environmental impact and/or aesthetic appearance were more likely to state that they will increase their use of EWPs. The results also show that influence on material selection, knowledge of EWPs, experience of the use of EWPs, and the architect's own attitude to the use of EWPs affect the likelihood of an increased use.

  • 48.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Characterization of Mould Fungi Growth on Scots Pine Sapwood Surfaces2019Licentiate thesis, comprehensive summary (Other academic)
  • 49.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sidorova, Ekaterina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hyperspectral Imaging Surface Analysis for Dried and Thermally Modified Wood: An Exploratory Study2018In: Journal of Spectroscopy, ISSN 2314-4920, E-ISSN 2314-4939, article id 7423501Article in journal (Refereed)
    Abstract [en]

    Naturally seasoned, kiln-dried, and thermally modified wood has been studied by hyperspectral near-infrared imaging between 980 and 2500 nm in order to obtain spatial chemical information. Evince software was used to explore, preprocess, and analyse spectral data from image pixels and link these data to chemical information via spectral wavelength assignment. A PCA model showed that regions with high absorbance were related to extractives with phenolic groups and aliphatic hydrocarbons. The sharp wavelength band at 2135 nm was found by multivariate analysis to be useful for multivariate calibration. This peak represents the largest variation that characterizes the knot area and can be related to areas in wood rich in hydrocarbons and phenol, and it can perhaps be used for future calibration of other wood surfaces. The discriminant analysis of thermally treated wood showed the strongest differentiation between the planed and rip-cut wood surfaces and a fairly clear discrimination between the two thermal processes. The wavelength band at 2100 nm showed the greatest difference and may correspond to stretching of C=O-O of polymeric acetyl groups, but this requires confirmation by chemical analysis.

  • 50.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards2018In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 10, article id e0204212Article in journal (Refereed)
    Abstract [en]

    During industrial wood drying, extractives migrate towards the wood surfaces and make the material more susceptible to photo/biodegradation. The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS). The concentration of total extractives was significantly higher in kiln-dried than in air-dried samples and was higher close to the surface than in the layers beneath. The scatter in the values for the lipophilic extractives was high in both drying types, being highest for linoleic acid and slightly lower for palmitic, oleic and stearic acids. The amount of fatty acids was low in kiln-dried boards, probably due to a stronger degradation due to the high temperature employed. The most abundant resin acid was dehydroabietic acid followed by pimaric, isopimaric, and abietic acids in both drying types. It is concluded that during kiln-drying a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm.

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