lnu.sePublikasjoner
Endre søk
Begrens søket
1 - 17 of 17
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Larissa, Greece.
    Karageorgos, Anthony
    Passialis, Costas
    Chavenetidou, Marina
    Mathematical approach for defining juvenile-mature wood transition zone in black locust and chestnut2011Inngår i: Wood and Fiber Science, ISSN 0735-6161, nr 3, s. 336-342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article defines age of transition from juvenile to mature wood in two ring-porous species, black locust (Robinia pseudoacacia L.) and chestnut (Castanea sativa Mill.). A logistic function was proposed using fiber length and ring width data of three black locust trees, aged 35-37 yr, and five chestnut coppice trees, aged 25-27 yr, from Sithonia Peninsula, Chalkidiki, Greece. The approach proved to be practical and objective in delineating maturity zones, and it was based on rate of change of yearly fiber length. The juvenile wood zone spread to the sixth growth ring from the pith in both species, whereas the demarcation of juvenile and mature wood was at age 12 and 14 yr in chestnut and black locust, respectively. Transition zone width comprised rings 7-12 in chestnut and rings 7-14 in black locust.

  • 2.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Karditsa, Greece.
    Oliver, José-Vicente
    AIDIMA, Spain.
    Fiber composition of packaging grade papers as determined by the Graff “C” staining test2006Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 38, nr 4, s. 567-575Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A qualitative and quantitative analysis of the fiber components of 15 representative papers that are used for the production of corrugated board was carried out by the Graff "C" staining test. The method of processing of softwood, hardwood, and nonwood fibers was determined under a light microscope by their color reactions with the stain. All papers, due to the use of recycled pulp raw materials in their manufacturing, were found to incorporate in their furnish fibers that had been produced with a variety of pulping processes: chemical, mechanical, and semi-mechanical. The recycled-based papers (recycled-liner and recycled-medium) were proved to be the most variable comprising 12-15 different fiber components, while in some of the semi-chemicals only up to 7 components were identified. The weight percentages of the fiber components calculated by the application of weight factors showed that in almost all papers the most important fiber component from a quantitative standpoint was hardwood unbleached kraft followed by softwood unbleached kraft. Besides hardwood unbleached semi-chemical pulp and mechanical softwood pulp that were also plentiful in the papers, there was a smaller number of other components which sum, however, accounted for a significant fraction in the total furnish weight. The results taken on the total softwood, hardwood, and nonwood fibers content of the papers demonstrate that Graff "C" staining test is adequate to analyze both the structure and quality of packaging grade papers in practical industrial testing.

  • 3.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Karditsa, Greece.
    Passialis, Costas
    Technological Educational Institute of Karditsa, Greece.
    Voulgaridis, Elias
    Aristotle University of Thessaloniki, Greece.
    Strength properties of juvenile and mature wood in black locust (Robinia pseudoacacia L.)2007Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 39, nr 2, s. 241-249Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study was undertaken to investigate the strength properties of juvenile and mature wood in black locust (Robinia pseudoacacia L.). Wood specimens were prepared from various stem heights, up to 9 m, of five naturally-grown black locust trees, 21-37 years old. Mechanical properties tested included moduli of rupture (MOR) and elasticity (MOE), and pure modulus of elasticity (PMOE) in static bending, stress wave modulus of elasticity (SWMOE) in dynamic strength, axial compression, and toughness. Comparisons between juvenile and mature wood specimens of similar densities (0.667-0.894 g/cm3 and 0.682-0.892 g/cm3, respectively) showed that juvenile wood had a statistically significant lower mean MOR (138.78 N/mm2), MOE (13,936 N/mm2), PMOE (18,125 N/mm2), SWMOE (16,813 N/mm2) and toughness strength (155.25 KJ/m2) than the mature wood (148.29 N/mm2, 14,747 N/mm2, 19,498 N/mm2, 17,635 N/mm2 and 181.27 KJ/m2, respectively). On the contrary, no statistically significant differences were found for the mean strength in axial compression among juvenile (63.75 N/mm2) and mature wood (66.65 N/mm2). Fractured surfaces of juvenile and mature wood specimens in static bending and toughness were classified into the "splintering tension" type of failure, while compression failures were of the "shearing type" according to ASTM D 143-83 standards. Lower strength of juvenile wood in most of the properties examined may be attributed to anatomical and chemical properties rather than density of wood specimens. The adverse influence of juvenile wood on strength properties should be considered for effective management (e.g. longer rotation age and other genetic and forest or plantation management measures that reduce juvenile wood content) and utilization of the species.

  • 4.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology, Sweden.
    Morén, Tom
    Luleå University of Technology, Sweden.
    Moisture properties of heat-treated Scots pine and Norway spruce sapwood impregnated with wood preservatives2012Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 44, nr 1, s. 85-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An experiment was conducted on commercially heat-treated (HT) Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst.) sapwood collected from Ht Wood AB, Arvidsjaur, Sweden. Secondary treatment on HT wood was performed in laboratory scale by impregnating with water-repellent preservatives (a commercial one and pine tar) to evaluate their retention and different moisture-related properties. Preservative solutions were impregnated using a simple and effective method. Wood samples were heated at 170°C in a dry oven and were immediately immersed in preservative solutions. Considerable retention was observed in HT wood, particularly in pine. Moisture adsorption properties were measured after conditioning in a high-humidity environmental chamber (4°C and 84% RH). Experimental results showed that secondary treatment enhanced moisture excluding efficiencies by decreasing equilibrium moisture content, suggesting better hydrophobicity. Soaking test in water showed that antiswelling and water repellence efficiencies improved, especially in tar-treated wood. In addition, this type of treatment significantly decreased water absorption. It was also possible to decrease volumetric swellings. Thus, secondary treatment of HT wood with preservative, in particular with tar, improved dimensional stability and water repellency.

  • 5.
    Briggert, Andreas
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Hu, Min
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Oscarsson, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Tracheid effect scanning and evaluation of in-plane and out-of-plane fibre direction in Norway spruce using2018Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 50, nr 4, s. 411-429Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Local fiber direction is decisive for both strength and stiffness in timber. In-plane fiber direction on surfaces of timber can be determined using the so-called tracheid effect which is frequently used in both research and industry applications. However, a similar established method does not exist for measuring the out-of-plane angle, also known as diving angle. The purposes of this article were to evaluate if the tracheid effect can also be used to determine, with reasonable accuracy, the out-of-plane angle in Norway spruce and to verify an existing mathematical model used to calculate the fiber direction in the vicinity of knots. A newly developed laboratory laser scanner was applied for assessment of fiber directions in a single Norway spruce specimen containing a knot. It was assumed that the specimen had a plane of symmetry through the center of the knot, and by splitting the specimen through this plane into two parts, it was possible to make measurements on orthogonal planes. The results showed that the out-of-plane angle could not be determined with very high accuracy and the difficulties related to this objective were analyzed. Regarding the mathematical model of fiber direction in the vicinity of a knot, fiber directions calculated on the basis of this model agreed well with experimentally obtained fiber directions, but successful application of the model requires that the geometry of the knot is known in detail.

  • 6.
    Florisson, Sara
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Muszynski, L.
    Oregon State University, USA.
    Vessby, Johan
    Karlstad University, Sweden.
    Analysis of hygro-mechanical behavior of wood in bending2021Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 53, nr 1, s. 27-47Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The empirical test developed as validation for a newbeamelementmodel that can account for bothmechanical and environmental load action in finite element analysis is presented. The testing protocol allowsfor the identification and analysis of contributing deflection components in bending under varying MCconditions, including mechano-sorption. The components of deflection in the shear-free span of a four-pointbending test and their responses to varyingmoisture are evaluatedwith an analytical procedure. The experimentwas conducted on clear, straight-grained sapwood and heartwood specimens of Norway spruce (Picea abies)(30 15 640 mm3). The program consisted of three phases: 1) long-term (LT) experiments under constanttemperature of 60°C and RH cycles between 40% and 80%, 2) a short-term static experiment to determine thevariation in the sample set and the load level of the LT experiment on end-matched specimens, and 3) creeptests at 60°C and constant humidity at either 40%or 80%to determine the effect ofmoisture on the viscoelasticcreep. Mass changes and hygro-expansion measured on matched specimens were used in the analyticalmethod. Constitutive models used for describing the material-level response to loads and moisture changeswere applied to the shear-free segment of the specimens disregarding actual moisture gradients and fiberorientation inside the test specimens. A successful identification of each deflection component and isolation ofmechano-sorption component was accomplished. In the 90 da of testing, the dominant component of the totaldeflection was the elastic component, followed by the mechano-sorptive component. Creep was found to benonnegligible and important in the correct description of mechano-sorption. The effect of moisture on theviscoelastic behavior showedmost important during loading and first stages of decreasing deflection rate phase.

    Fulltekst (pdf)
    fulltext
  • 7.
    Florisson, Sara
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Vessby, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    A numerical study of the effect of green-state moisture content on stress development in timber boards during drying2019Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 51, nr 1, s. 41-57Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Timber boards manufactured with a traditional sawing pattern often contain both heartwood andsapwood. In such boards, internal constraints can occur during drying because of a radial variation in greenstate(GS) MC between the heartwood (30-60%) and sapwood region (120-200%). Despite such knowledge,the initial MC is seldom considered when evaluating kiln-drying schedules. The effect of GS MC on thedevelopment of tangential tensile stress during drying is studied for four types of timber boards. A numericalmodel was developed that can simulate transient nonlinear orthotropic moisture flow and moisture–inducedstress and distortion in wood with the use of the finite element method. The stress analysis considers elastic,hygroscopic, and mechano-sorptive strain. The study shows that the GS MC does not significantly influencethe maximum stress state, but that it does influence the time at which the maximum tangential tensile stressoccurs at different exchange surfaces. This results in several periods in the drying schedule where unfavorablehigh stress situations in the tangential direction arise, which could lead to crack propagation.

    Fulltekst (pdf)
    fulltext
  • 8.
    Grubîi, Victor
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Caceres, Claudia B.
    Université Laval, Canada.
    Hernandez, Roger E.
    Université Laval, Canada.
    Blais, Carl
    Effect of Chipping Edge Inclination Angle on Size Distribution of Pulp Chips Produced by Chipper-Canter2019Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 51, nr 4, s. 402-415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of oblique cutting on the chipper-canter wood chipping mechanism was studied. A bent knife was modified to obtain inclination angles (IA) of 30° and 50° between the chipping edge and the log feeding direction. The standard knife had an IA of 40°. These three knives were tested on 15 logs each, under frozen (-10°C) and unfrozen conditions. Chip dimensions were assessed by thickness (Domtar distribution) and width/length (Williams distribution). Characteristics and physical properties of the log knots were also measured. Experiments revealed that IA had a significant effect on chip formation mechanism. The IA affected  the chipping edge entering the log and the form of the wood slice that was transforming into chips. These changes provoked variations in chip size. An IA of 30° produced wider chips, mostly in the first half of the cut, shaped as an elongated parallelepiped that resulted from a tangential, oblique and radial splitting in a single chip. The shape of chips obtained with IAs of 40° and 50° was more like an upright parallelepiped that was detached mostly by radial and oblique splitting. At the beginning and at the end of the cut, chips were produced by tangential splitting. As a result, for a same chip length of 23 mm, weighted mean chip thickness (WCT) decreased almost 1 mm when IA decreased from 50° to 30°. The knot ratio (total knot area / cant total area) affected both chip size distributions and WCT. Chipping frozen wood at -10°C reduced the chip thickness by 0.55 mm with respect to unfrozen wood. The amount of fines and pin chips also increased nearly two times compared to unfrozen wood. The amount of the Williams accepts chip class increased by 6% when IA decreased from 50° to 30° and by 8% when chipping unfrozen wood compared to frozen wood.

  • 9.
    Hu, Min
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Johansson, Marie
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Oscarsson, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Serrano, Erik
    Lund University.
    Assessment of a Three-Dimensional Fiber Orientation Model for Timber2016Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 48, nr 4, s. 271-290Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wood is an orthotropic material with very different properties along and across fibers, and every board has its own pattern of knots and fiber deviations. Therefore, detailed knowledge of the three-dimensional (3D) fiber orientation of individual boards would enable more accurate assessment of properties such as stiffness, strength, and shape stability. This paper presents a method for modeling 3D fiber orientation of side boards of Norway spruce. The method is based on dot laser scanning and utilization of the tracheid effect, and it is verified by a comparison between strain fields calculated on the basis of the fiber orientation model and corresponding strains determined using digital image correlation (DIC) technique. By means of the method, it is possible to identify knots and to reproduce the fiber orientation in clear wood in the vicinity of knots. Fiber orientation models of side boards including traversing edge knots were established and integrated in finite element models of boards used for simulation of four-point bending tests. The same boards were also tested in laboratory and displacement fields of the wide faces were recorded at different load levels using DIC technique. Comparisons of strain fields from measurements and simulations showed close agreement, regarding both strain patterns and strain levels. Local strain concentrations caused by very small defects were detected using the models and also found from the laboratory test results. The modeling approach may be used both to achieve improved accuracy of existing machine strength grading methods and, after further development, also for more advanced analysis of eg crack propagation and strength of timber.

  • 10.
    Kifetew, Girma
    et al.
    Kungliga Tekniska högskolan (KTH).
    Sandberg, Dick
    Kungliga Tekniska högskolan (KTH).
    Material damage due to electron beam during testing in the environmental scanning electron microscope (ESEM).2000Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 32, nr 1, s. 44-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study describes the development of cell-wall damage, i.e., the creation of cracks across or in the vicinity of pits during the testing of twenty microtomed spruce (Picea abies karst.) samples in the Environmental Scanning Electron Microscope (ESEM). Samples were investigated both in an unloaded condition and under a constant tensile load and at different moisture levels. Regions of the moisture-cycled samples that had been exposed to an electron beam during image acquisition showed damage running through pits and their surroundings. Specimens loaded in the green condition and dried in the chamber for 2 h without beam exposure except during imaging showed no noticeable cell-wall damage. The results indicate that the electron beam may be a major source of damage initiation. Therefore, it is essential to note the circumstances of the rest when explaining the observations made in ESEM studies.

  • 11.
    Nilsson, Jonaz
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Bending and Creep Deformation of a Wood-Based Lightweight Panel: An Experimental Study2019Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 51, nr 1, s. 16-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    When wood is exposed to long-term loading, creep deformation can occur because of its viscoelastic characteristic. The aim of this study was to increase the understanding and knowledge of creep deformation of a wood-based lightweight sandwich-type panel and to see if this type of panel has similar properties for creep as solid wood has. This was done by means of a study based on experiments. The panel studied consisted of two face sheets of beech wood and a core of pinewood struts cross-glued to the face sheets. A solid beech panel was used as a reference. In all, there were 27 samples for the test. The densities of the lightweight panel varied from 165 to 297 kg/m(3), compared with the density of the solid panel of 705 kg/m(3). The study consisted of two parts: a bending test and a creep test. The bending test was used to determine the maximum failure load for the panel. For the creep test, 30% of the original failure load was used. When the results from the bending tests were ranked for load capacity in relation to density, the results for the lightweight panel varied from 9.0 to 18.0 m(4)/s(2), compared with the value of the reference panel at 27.3 m(4)/s(2). This measured how effective the panel was in withstanding bending loads in relation to their density. However, this was not to say that the panel with the highest value also took the highest load in absolute terms. If the creep deformation is instead ranked in relation to density, the results for the lightweight panel varied from 10.4 to 33.7 kg/m, compared with the value of the reference panel at 45.5 kg/m. As with the bending test, these values rank how effective the panel was in resisting creep deformation in relation to density.

  • 12.
    Olsson, Anders
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Pot, G.
    Univ Bourgogne Franche Comte, France.
    Viguier, J.
    Univ Bourgogne Franche Comte, France.
    Hu, Min
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Oscarsson, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Performance of timber board models for prediction of local bending stiffness and strength-with application on douglas fir sawn timber2022Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 54, nr 4, s. 226-245Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Efficient utilization of structural timber requires accurate methods for machine strength grad-ing. One of the most accurate methods presented this far is based on data of local fiber orientation on board surfaces, obtained from laser scanning. In this paper, two potential improvements of this method are exam-ined. The first one consists of replacing a model based on simple integration over cross sections of boards for calculation of local bending stiffness by a 3D solid finite element (FE) model from which local bending stiffness is derived. The second improvement concerns replacement of a simple model for the fiber orienta-tion in the interior of board by a more advanced one taking location of pith and growth direction of knots into account. Application of the alternative models on a sample of more than 200 Douglas fir boards, size 40 mm x 100 mm x 3000 mm, cut from large logs, show that each of the evaluated model improvements contributes to improved grading accuracy. When local bending stiffness is calculated utilizing the herein suggested FE model in combination with the improved model of fiber orientation in the interior of boards, a coefficient of determination to bending strength as high as 0.76 is obtained. For comparison, a coefficient of determination of 0.71 is obtain using the simpler original models.

    Fulltekst (pdf)
    fulltext
  • 13.
    Ormarsson, Sigurdur
    et al.
    Chalmers University of Technology.
    Cown, Dave
    Forest Res, Wood Qual & Solid Wood Prod, New Zealand.
    Moisture-Related Distortion of Timber Boards of Radiata Pine: Comparison with Norway Spruce2005Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 37, nr 3, s. 424-436Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Based on material data obtained by several researchers at Forest Research in New Zealand, with respect to variations in the main material properties from pith to bark, the distortion model developed earlier for Norway spruce has been further modified for radiata pine. Numerical simulations were performed for both pine and spruce to investigate how different sawn pattern options affect the shape stability of individual boards. Results for spruce presented earlier have shown clearly that warping of the timber products is strongly influenced by the annual ring patterns within the individual boards. Comparisons between the two species were performed to study how the radial variations in the basic properties such as shrinkage parameters, stiffness parameters, and spiral grain have influence on the warping. Generally, the intrinsic patterns of variation in wood properties within stems were similar, and both species show a tendency to distort with changing moisture environment. There are strong indications that intelligent re-combination of material in glued products may overcome many of the inherent problems in using biological material with predictable variation in material properties. Keyword: Finite element simulations, Pinus radiata, shrinkage, spiral grain, distortions, wood, timber boards

  • 14.
    Oscarsson, Jan
    et al.
    SP Technical Research Institute of Sweden, Sweden.
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Enquist, Bertil
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Localized modulus of elasticity in timber and its significance for the accuracy of machine strength grading2014Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 46, nr 4, s. 489-501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    From previous research, it is well known that a localized modulus of elasticity (MOE) is a better indicating property (IP) of strength than an MOE averaged across a longer span. In this study, it was investigated to what extent the relationship, in terms of coefficient of determination (R2), between strength and localized MOE was dependent on the length across which the MOE was determined. Localized MOE was calculated with MOE profiles based on dot laser scanning of fiber directions, axial dynamic excitation, and a scheme of integration across a board's cross-section. Two board samples were investigated. Maximum R2 values, which were as high as 0.68 and 0.77, respectively, were obtained for localized MOE determined across lengths corresponding to about half the depth of the investigated boards. Consequently, application of a highly localized bending MOE as an IP will result in very competitive grading.

  • 15.
    Osman, Syaiful
    et al.
    Universiti Teknologi MARA, Malaysia.
    Ahmad, Mansur
    Universiti Teknologi MARA, Malaysia.
    Zakaria, Mohd Nazarudin
    Universiti Teknologi MARA, Malaysia.
    Bakar, Balkis Fatomer A.
    Universiti Putra Malaysia Serdang, Malaysia.
    Abu, Falah
    Universiti Teknologi MARA, Malaysia.
    Kamarudin, Siti Hasnah
    Universiti Teknologi MARA, Malaysia.
    Bahari, Shahril Anuar
    Universiti Teknologi MARA, Malaysia.
    Hosseinpourpia, Reza
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Linnéuniversitetet, Kunskapsmiljöer Linné, Avancerade material. Linnéuniversitetet, Kunskapsmiljöer Linné, Grön hållbar utveckling.
    Variation of chemical properties, crystalline structure and calorific values of native Malaysian bamboo species2022Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 54, nr 3, s. 173-186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chemical properties of four common Malaysian bamboo species locally known as Beting (Gigantochloa levis), Semantan (Gigantochloa scortechinii), Lemang (Schizostachyum brachyladum) and Akar (Bambusa vulgaris) were studied. Chemical analysis shows that the alkaline extractive content for Malaysian bamboo species studied was within 24.4% to 25.6%, ethanol-toluene extractive content for Malaysian bamboo species was within 4.0% to 7.2% and water extractive content was within 10.4% to 12.8%. The average value of holocellulose content for Malaysian bamboo was between 64.5% to 70.67%, Klason lignin within 25.3% to 28.4%, cellulose content was between 28.5% to 33.8% and α-cellulose content for all bamboo species was within the range of 40.7% to 47.9%. The crystallinity of bamboo samples was between 42.0 to 44.4%, indicating their semi-crystalline structure.  Heating value of bamboo ranged between 17.0 MJ/kg to 18.1 MJ/kg with G. scortechinii having the highest heating value.. The Inductive Couple Plasma Atomic Emission Spectroscopy (ICP-ES) analysis showed that Potassium (K) and Calcium (C) were the major elements in the ash of all bamboo samples. This study demonstrates the potential of native bamboo species as an alternative sustainable raw material to wood for a wide range of applications.

    Fulltekst (pdf)
    fulltext
  • 16.
    Sjökvist, Tinh
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Niklewski, Jonas
    Lund university, Sweden.
    Blom, Åsa
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Effect of wood density and cracks on the moisture content of coated Norway spruce (Picea abies (L.) Karst.)2019Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 51, nr 2, s. 160-172Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A protective coating is often used on the cladding of wooden facades to limit the absorption of moisture. Low wood moisture content (MC) is essential to obtain satisfactory durability performance. Wood density is known to influence the water sorption and crack formation of uncoated wood. However, the effect of density on the aforementioned behaviors of coated spruce is not yet fully understood. Six-years of data on the crack formation and the MC variation of outdoor exposed panels are analyzed in this article. The outdoor test was complemented by a subsequent laboratory experiment, wherein the MC variation was monitored at different depths on the board during artificial water spraying. The aim of this research was to increase the knowledge about how wood density and aging affect the water sorption of coated spruce through the crack formation. The results indicated that wood density had an impact on the overall sorption behavior of coated spruce. Low-density spruce contributed to faster water absorption and desorption processes than coated samples with higher density. However, the observed correlation to density was limited to a condition with an intact coating. High-density characteristics contributed to more crack formation, and the density–sorption relationship reversed with a cracked coating. A cracked coating caused a strong local increase in the MC of the wood at the location of the cracks. Weather-exposed replicates without cracks had a higher MC in the core of the board compared with the value beneath the coating. The higher MC is probably due to the water sorption of the uncoated backside of the panel. Such an occurrence raised awareness for future studies to account for multidimensional sorption behavior from all sides of the panel. The local difference in MC also raises awareness for future studies to investigate local MC variations (as opposed to the global average of the panel) in research on the durability of coated wood.

  • 17.
    Östman, Birgit
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Schmid, Joachim
    Swiss Fed Inst Technol, Switzerland.
    Klippel, Michael
    Swiss Fed Inst Technol, Switzerland.
    Just, Alar
    Tallinna University of Technology, Estonia;RISE, Sweden.
    Werther, Norman
    Tech Univ Munich, Germany.
    Brandon, Daniel
    RISE, Sweden.
    Fire Design of CLT in Europe2018Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 50, s. 68-82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fire safety design of cross-laminated timber (CLT or X-Lam) in Europe is governed by the Construction Products Regulation and its essential requirements, as for all other building products. These requirements are mandatory, to be used in all European countries. They include classification systems for reaction to fire of building products, fire resistance of building elements, and structural Eurocodes. The reaction-to-fire performance of CLT in accordance with the European classification system is specified. Higher classes can be reached by chemical treatments, but the durability of the reaction-to-fire performance needs to be fulfilled according to a new European system. The fire resistance design of CLT building elements is not included in Eurocode 5, the structural Eurocode for timber, but can be either tested according to European standards or calculated by using design methods being developed recently. This article provides information about both reaction to fire and fire resistance of CLT in Europe. Furthermore, the importance of proper detailing in building design and in practice is stressed. Finally, performance-based design is introduced and some further research needs suggested.

1 - 17 of 17
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf