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  • 1.
    Sandberg, Dick
    Högskolan i Kalmar, Institutionen för teknik.
    A sawing station and a method of using the sawing station.1999Patent (Övrig (populärvetenskap, debatt, mm))
  • 2.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    PrimWood: The guiding-star for the wood industry1999Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A doctoral thesis is the result of about five years' intensive work within a special field, in my case wood technology. The research results which are produced during these years are presented in the form of a thesis.

       Theses are unfortunately often written for like-minded people, i.e. by scientists for scientists and with a detailed language which is difficult to understand. The result is that very few persons read the theses although the content may well be of value to a broader circle of readers.

       However, I have during my whole research period considered it important that the research results shall be understood by people in the branch.

       This booklet is an attempt to describe briefly the most important results presented in my doctoral thesis. I also wish to illuminate more or less forgotten knowledge about the annual ring orientation in wood.

       The general aim is to try to facilitate the communication between wood research and the industry in order to achieve a more efficient utilization of the research results.

  • 3. Adamopoulos, Stergios
    Silvicultural practices in relation to quality of timber produced in Greece1999Ingår i: 2nd Workshop of COST Action E10: Wood properties for Industrial Use, 13-15 June, Tapada de Mafra, Portugal, 1999, 50-53 s.Konferensbidrag (Övrigt vetenskapligt)
  • 4.
    Säll, Harald
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Dahlblom, OlaLund University.
    Silviculture Influence on Spiral Grain in Norway Spruce1999Proceedings (redaktörskap) (Övrigt vetenskapligt)
    Abstract [en]

    In the present investigation a significant variation of spiral grain with annual ring number as well as with height in stem was observed. It was also observed that the spiral grain may be significantly different in stands with different site conditions and silvicultural treatment. It will however require further research to gain knowledge about to what extent differences in spiral grain in different stands are due to site conditions and to what extent they are due to silvicultural treatment. In addition to site conditions and silvicultural treatment the development of spiral grain may be affected by the genetics of the trees.

  • 5. Kifetew, G
    The influence of the geometrical distribution of cell-wall tissues on the transverse anisotropic dimensional changes of softwood1999Ingår i: Holzforschung, ISSN 0018-3830, Vol. 53, nr 4, 347-349 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of the geometrical distribution of cell-wall tissues on the transverse anisotropic dimensional changes of softwood has been studied using two isotropic models. A finite element model has been used to calculate the thermal expansion of two aluminium plates without and with holes in the two perpendicular directions. Moisture expansion measurements in the two perpendicular directions were conducted using a polyamide (PA6) plate containing several holes. No differences were found in either the thermal expansion of the aluminium plates or the moisture expansion of the PA6 plate between the two perpendicular directions. Thus, the investigation suggests that the geometrical distribution of cell-wall tissues has no effect on the transverse anisotropic shrinkage of softwood.

  • 6.
    Hameed, Mahmood
    et al.
    University of Göttingen, Germany.
    Roffael, Edmone
    University of Göttingen, Germany.
    Veränderung des Gehaltes an Ethanol-Cyclohexan-Extrakten von Kiefernsplint- und kernholzspänen infolge thermischer Behandlung: [Decrease in the extractive content (ethanol-cyclohexane) of Chips from sapwood and heartwood of Pine (Pinus sylvestris L.) due to thermal treatment]1999Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 57, nr 4, 294-295 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Decrease in the extractive content (ethanol-cyclohexane) of Chips from sapwood and heartwood of Pine (Pinus sylvestris L.) due to thermal treatment at 103 °C. 

  • 7.
    Sandberg, Dick
    Kungliga Tekniska högskolan (KTH).
    Weathering of Radial and Tangential Wood Surfaces of Pine and Spruce.1999Ingår i: Holzforschung, ISSN 0018-3830, Vol. 53, nr 4, 355-364 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of cracks and changes in appearance have been investigated on radial and tangential surfaces of pine (Pinus silvestris L.) and spruce (Picea abies Karst.) which have been exposed outdoors for 33 months. The degradation of the surfaces has also been studied at the micro-level. Untreated samples, samples impregnated with a CCA-agent and samples surface treated with linseed oil have been tested. The annual ring orientation is the most important factor for crack development on weathering. The type of wood, impregnation treatment and surface treatment with linseed oil have only a marginal effect on the crack development. No relation has been found between the density of the samples and the crack development After 33 months of outdoor exposure, tangential surfaces of pine have 13 times more total crack length per unit area than the corresponding radial surfaces. In spruce, the total crack length on the tangential surfaces is 6 times greater than on the radial surfaces. Tangential surfaces of both pine and spruce have a greater number of cracks per unit area and wider cracks than the corresponding radial surfaces. Tangential and radial surfaces show the same colour change in the surface as a result of weathering. On the micro-level, tangential surfaces have more and deeper cracks than radial surfaces. The cracks on the tangential surfaces occur frequently in both earlywood and latewood. On radial surfaces, cracks occur primarily at the annual ring borders, but to a certain extent also in the earlywood. The radial cell wall of the earlywood has a large number of pits which are degraded at an early stage. Decomposition of the cell wall takes place on both radial and tangential surfaces. Cracks arise which follow the S2 fibril orientation in the cell-wall. Delamination in the middle lamella is especially noticeable in the latewood on tangential surfaces. No differences have been observed regarding linseed oil treatment, impregnation or type of wood.

  • 8.
    Hameed, Mahmood
    et al.
    Georg-August-Universität Göttingen, Germany.
    Roffael, Edmone
    Georg-August-Universität Göttingen, Germany.
    Über die Benetzbarkeit von Splint- und Kernholz der Kiefer, Douglasie und Lärche: [On the Wettability of sapwood and heartwood of various woods pieces (Pine, Douglas fir and Larch)]1999Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 57, nr 4, 287-293 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    On the wettability of sapwood and heartwood of various woodspecies (Pine, Douglas fir and larch) Results have established that the wettability of sapwood from three woodspecies (Pine, Douglas ®r and Larch) on the cross, radial and tangential section with water and various glues (UF-resins, PF-resins, MUPF-resins and PMDI-adhesive) is better than that of heartwood. In most cases, the tangential section in sapwood and heartwood was less wettable than radial and cross sections. Using alkaline phenolic resins which cause wood to swell, wettability in the tangential direction was improved.

  • 9.
    Sandberg, Dick
    et al.
    Kungliga Tekniska Högskolan.
    Holmberg, Hans
    KTH.
    Deformationer och sprickförekomst hos virke före och efter torkning.: Inverkan av virkets läge i stocken.1998Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Deformationer (flatböj, kantkrok, skevhet, kupning) oeh sprickforekomst har undersökts före och efter torkning för sågat virke av furu och gran. Dessa kvalitetssänkande faktorer har utvärderats med avseende på virkets läge i stocken, årsringsorientering i virkestvärsnittet, växtspanningar, juvenilved, märgläge och reaktionsved. Syftet har varit att klargöra om det nya sågmönstret Stjärnsågning ger skillnader ur deformations- och sprickhänseende hos det utsågade virket jamfört med traditionella sågmönster.

    Totalt 107 övergrova stockar (> 30 cm) har sönderdelats med tre olika sågmönster till totalt 749 virkesstycken. Deformationer och sprickförekomst har bestärnts för detta virke direkt vid sönderdelningen, samt efter torkning med påföljande konditionering under tre månader till fuktkvoten 9,5 %.

    Flatböj och kantkrok förekommer hos virket direkt efter sönderdelningen, vilket är ett resultat av växtspänningar i trädet som frigörs i och med såningen. Vid torkningen förändras flatböj och kantkrok till både storlek och riktning. Riktningsberoendet som uppträder är mest påtaglig hos det virke som är utsågat nära märgen. Dessa bitar är vanligtvis deforrnerade (konkava) mot splintsidan innan torkningen på grund av växtspanningar. Vid torkningen medför juvenilvedens större longitudinella krympning att deforrnationen mer eller mindre balanseras ut (virket blir mer rakt) eller att deforrnationen får motsatt riktning jarnfört före torkningen. Torkningen medför i allmänhet att antalet virkesstyeken med flatböj eller kantkrok minskar, medan motsvarande medelvärden ökar. Detta är oberoende av årsringsorienteringen i virket.

    Virket uppvisar ingen skevhet eller kupning omedelbart efter sönderdelningen. Skevhet och kupning uppkommer när virket torkas.

    Märgen och juvenilveden har en avgörande betydelse för graden av skevhet hos virket, vilket innebar att virke utsågat nära märgen har större skevhet än virke utsågat längre från märgen. Detta har samband med fiberorienteringen i virket.

    Kupningen är en följd av krympningsanisotropin i kombination med årsringskrökningen i virkets tvärsnitt. Det innebär att virket kupas vid torkningen så att den mest tangentiella flatsidan blir konkav. Kupningen ökar ju mer krökt årsringen är i tvärsnittet.

    Sprickor finns i virket redan före torkningen. Dessa sprickor härrör med all sannolikhet från sprickor som finns i det levande trädet. Mönstret for sprickförekomsten är detsarnrna för både furu oeh gran, nämligen att virket utsågat med eller nära märgen har betydligt större relativ spricklangd jämfört med virke utsågat längre bort från märgen.

    Sprickoma uppkommer främst på virkets märgsidor, vilket blir tydligare ju närmare märgen virket är utsågat. Spricklängden ökar eller minskar vid torkningen beroende på träslag och virkets läge i stocken.

    Stjämsågat virke med rektangulart tvärsnitt uppvisar efter torkningen flatböj och kantkrok i nivå med eller något lägre än övrigt virke. Virket med triangulärt tvärsnitt har i förhållande till det övriga virket stor flatböj efter torkning. Kantkroken ar förhållandevis liten. Trekantema uppvisar flatböj direkt efter sönderdelningen som är i nivå med det övriga virket. Den stora ökningen av flatböj som sker vid torkningen kan vara en följd av den metod som används för ströläggningen av virket.

    Det stjämsågade virket har ingen kupningen och mycket liten skevhet efter torkningen. Detta virke har också mycket få sprickor.

  • 10. Adamopoulos, Stergios
    et al.
    Voulgaridis, E
    Impregnation of timber and regulations applied to preservation practice in Greece1998Konferensbidrag (Refereegranskat)
    Abstract [en]

    The practice of wood preservation in Greece was started about 80 years ago and refer to creosote-treated timber used in ground contact (i.e. railway sleepers, poles). At present, three creosote impregnation plants and thirteen CCA or CCB units exist in Greece treating about 90.000 m3 of wood per year. Most of the research on wood preservation has been carried out in the last 15-20 years and refer to the application of creosote and water soluble preservatives (CCA, CCB) to native wood species. However, research on a number of specific topics of wood impregnation is lacking. Impregnation of wood is of great importance for Greece, a country with great wood deficit, and, for this reason, the elongation of wood durability is strongly desirable. On the other hand, the environmentally safe impregnation of timber and the use of preservatives in a non-hazardous manner to humans or animals are gaining an increasing importance. There are some national and EU regulations applied to the use of preservatives, while the Greek Organization of Standardization (ELOT) is responsible for approving European standards. The organizations of Greek Telecommunication, Electricity and Railway apply their own standards.

  • 11.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Inverkan av isostatisk komprimering på cellstrukturen1998Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Furuprover har komprimerats isostatiskt vid rumstemperatur i syfte att utvärdera vad som sker i cellstrukturen vid stora deformationer. Provema hade antingen stående eller liggande årsringar. Fuktkvoten vid komprimeringen var 10 %. Komprimeringsgraden har bestämts samt den återsvällning som erhålls när de komprimerade provema fuktas upp i vatten. Förändringar i cellstrukturen undersöktes i ESEM (Environmental Scanning Electron Microscope).

    Komprimeringen var 2,3 gånger, vilket innebar att densiteten ökade från i medeltal 539 kg/m3till 1218 kg/m3. Vårveden komprimerades betydligt mer än sommarveden. Komprimeringen var störst i radiell riktning som en följd av att sommarveden ej motverkade deformationen av vårveden, vilket är fallet i den tangentiella riktningen. I longitudinell riktning var komprimeringen mycket liten.

    Vid uppfuktningen av de komprimerade provema återgick komprimeringen till 90 %. I radiell riktning var återsvällningen 4 gånger större än i tangentiell riktning.

    Någon inverkan av årsringsorienteringen kunde inte påvisas. Vid ESEM-studien kunde omfattande sprickbildning i cellväggarna observeras i både vår- och sommarveden.

  • 12.
    Sandberg, Dick
    Högskolan i Kalmar, Institutionen för teknik.
    Method for cutting up logs.1998Patent (Övrig (populärvetenskap, debatt, mm))
  • 13.
    Sandberg, Dick
    et al.
    Kungliga Tekniska högskolan (KTH).
    Holmberg, Hans
    KTH.
    Radially sawn timber.: Gluing of star-sawn triangular profiles into form-stable products with vertical annual rings.1998Ingår i: Holz als Roh- und Werkstoff, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 56, nr 3, 171-177 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method is presented for the gluing of star-sawn triangular profiles of pine (Pinus silvestris L.) into form-stable wood products with vertical annual rings. The triangular profiles are free from pith and from most of the juvenile wood. The method is based on dried and conditioned triangular profiles. Undesired defects are removed and the wood is finger-jointed into long lengths. In the finger-jointing, consideration is given to the appearance and annual ring orientation of the jointed materials. After the jointing, the triangular profiles are planed and glued into rectangular blocks with vertical annual rings. These blocks can then e.g. be used as construction beams or be sawn up into solid wood panels. A pilot plant has been built for the manufacture of knot-free solid wood panels based on the proposed method. Results show a total volume yield of 53.8%. Three critical production stages can be distinguished: removal of knots and defects, planing, and division of blocks into boards. These three operations are together responsible for more than 93% of the total losses in the manufacture. The removal of knots and defects meant a volume loss of 12.8%. 13% of the manufactured units were 2.1 m long without finger-jointing and free from knots and other defects. The average length of the remaining pieces used for finger-jointed units was 0.41 m.

  • 14.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Stjärnsågning: ledstjärnan för svensk träindustri.1998Rapport (Övrigt vetenskapligt)
  • 15.
    Wiklund, Martin
    et al.
    KTH.
    Sandberg, Dick
    KTH, .
    The Concept of Value Activation - Wood Properties at Different Annual Ring Orientation in Pine (Pinus Silvestris L).1998Ingår i: Timber and Wood Composites for the Next Century / [ed] Song-Yung Wang and Min-Chyuan Yeh, 1998Konferensbidrag (Refereegranskat)
    Abstract [en]

    An integrated R&D program called "Value Activation" has been carried out for the past eight years at the Royal Institute of Technology, Div. of Wood Technology and Processing (KTH-Trä). The concept of Value Activation is focused on the basic understanding of wood, and the fact that there are properties that are not fully exploited in conventional wood manufacturing systems to date. The strategy is to activate these inherent properties by a better understanding of the fundamental behaviour of wood, combined with new applied process technology and the development of the required manufacturing systems.

    The Value Activation program has so far shown that there are great possibilities of utilizing the properties of wood in a better way than our conventional wood production concept can achieve. New wood products with desirable properties can be developed. Most of these products are expected to give a greater added value to the wood. The R&D program will continue with the further development of improved products and also with the development of cost-efficient production systems for implementing the ideas from our R&D in profitable production units.

    Within the Value Activation program the following properties, which were judged to be the most important ones for future wood products were chosen:

    • Aesthetic and tactile factors
    • Controlled moisture movements
    • Accuracy in size and geometry
    • No checks and splits
    • Strength and hardness

    These properties are all strongly influenced by the annual ring orientation in the cross section of the sawn timber. This paper describes the influence of the annual ring orientation on these properties and how they can be improved by using a new sawing pattern.

  • 16.
    Sandberg, Dick
    et al.
    Kungliga Tekniska Högskolan.
    Wiklund, Martin
    KTH.
    The Concept of Value Activation: the PrimWood Method for Improved Properties.1998Ingår i: Timber and Wood Composites for the Next Century / [ed] Song-Yung Wang and Min-Chyuan Yeh, 1998Konferensbidrag (Refereegranskat)
    Abstract [en]

    Value Activation is an integrated R&D programme carried out for the last eight years at the Royal Institute of Technology, Wood Technology and Processing. The name Value Activation refers to the basic understanding ofwood, where at present there are properties that are not fully exploited, but with help of a new sawing pattern could be fully utilized. The basic idea lies at an industrial level producing radially sawn timber with good profitability and with a lesser and mostly a controllable moisture movement. In short it implies an activation of values of timber, that has not been exploited in ordinary industrial production to date. This paper gives one example how the basic ideas in the concept of

    Value Activation have been implemented to the industry. A new manufacturing system, the Prim Wood Method, has been proposed in order to improve the utilization of wood. One basic idea within this method is a new sawing pattern called star-sawing, which produces timber with two different shapes, viz., timber with rectangular and triangular cross sections. This method facilitates an efficient production of radially sawn timber with vertical annual rings, and without pith and juvenile wood. The triangles produced in star-sawing are used for producing high quality, knot free panels with vertical annual rings, PrimWood Prism. In this process, the timber is finger-jointed to form knot-free lengths and glued together into a block. This block can then be divided according to thickness into boards with vertical annual rings. In star-sawing, a certain volume of clear pieces will be obtained which are relatively long, i.e. longer than 1 metre. It is not desirable to finger-joint these boards, but instead to manufacture PrimWood Prism without a finger-joint. The first full-scale industrial plants based on the Value Activation concept are now in production in nothern Sweden. At full capacity, the saw mill will produce around 18000 m3 of star-sawn pine a year and shift. The plant for Prim Wood Prism will produce around 5 000 m3 a year and shift. The company is expect to generate two to three times the usual value from each log.

  • 17. Kifetew, G
    et al.
    Thuvander, F
    Berglund, L
    Lindberg, H
    The effect of drying on wood fracture surfaces from specimens loaded in wet condition1998Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 32, nr 2, 83-94 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The study describes the effect of drying on fracture surfaces of Scots pine Pinus silvestris L. Microtomed specimens of isolated and combined early- and latewood, in green and oven-dried/resoaked state were loaded to failure in uniaxial tension parallel to the grain. The fracture surfaces were studied using scanning electron microscopy (SEM). Both green early-and latewood samples showed rough fracture surfaces, which in latewood was dominated by intrawall failure. In the resoaked state, transwall failure dominated and fracture surfaces were more flat, indicating a more brittle fracture process. Although variation in the data was large, the strength of the resoaked samples were generally lower than those of paired green samples. The observations support irreversible cell wall damage formed during drying which severely affects the failure mechanism.

  • 18.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Trä utomhus: årsringarnas betydelse för sprickbildning1998Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    När trä används utomhus, spelar det någon roll för åldrandet av virket hur det har sågats i förhållande till årsringarna? Undersökningar av furu- och granytor, som exponerats utomhus under flera år, visar att den exponerade ytans förhållande till årsringarna har betydelse för sprickbildningen. Virke med stående årsringar spricker betydligt mindre än virke med liggande årsringar.

  • 19.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Value Activation with vertical annual rings - material, production, products.1998Doktorsavhandling, monografi (Övrigt vetenskapligt)
  • 20.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Årsringsorienteringens inverkan på deformationer hos små felfria prover av furu under böjbelastning och samtidig fuktvariation.1998Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Syftet med föreliggande undersökning har varit att undersöka om skador uppstår i cellväggen då trämaterialet utsätts för fuktvariation under samtidig konstant belastning.

    Provkkroppar av felfri furuplint (10 x 10 x 400 mm) har utsatts för fyrpunkts böjbelastning under cykliskt varierande fuktkvot, 5/17 %. Proverna har utsatts för fyra belastningsnivåer: 0, 5, 20 respektive 40 % av böjbrottlastenvid 8,3 ±0,2% fuktkvot för matchande provkroppar. Lastriktningen var antingen radiellt eller tangentiellt årsringarna. Utböjningen samt vridningen (torsion) hos proverna har bestämts. Efter att själva krypförsöket har avslutats har delar av provmaterialet undersökts i ESEM.

    Följande nämnvärda reslutat har observerats:

    -Radiellt belastade prover vrider sig mer än tangentiellt belastade.

    -De radiellt belastade proverna vrider sig i olika riktningar beroende på om provets kärn- eller splintsida är dragbelastad.

    -Ingen skillnad i utböjning mellan radiellt och tangentiellt belastade prover

    -Lastnivån inverkar på både utböjning och vridning

    - Deformation kvarstår efter avlastning och påföljande funktcykling

    -Skador i form av sprickor och veckbildning i cellväggarna uppkommer hos de prover som under belastning utsatts för varieranade fuktkvot. Skadorna tilltar med ökad belastning.

    Den genomförda undersökningen visar att årsrings- och fiberorienteringen inverkar på deformationen vid böjbelastning på sådant sätt att provkroppar uppvisar olika deformationsbeteende beroende på lastens riktning i förhållande till årsringsorienteringen i provernas tvärsnitt.

    Vidare visar undersökningen att krypning, vid belastningsnivåer mellan 5 och 40 %, medför skador i cellstrukturen och att dessa skador till viss del kan var förklaringen till att deformationen vid avlastning och efterföljande fuktcykling ej är helt återgående.

  • 21.
    Sandberg, Dick
    et al.
    Kungliga Tekniska högskolan (KTH).
    Stehr, Micael
    KTH Träteknologi.
    Bending strength of I-beams with webs of wood-fibre board and flanges of star-sawn triangular profiles.1997Ingår i: Holz als Roh- und Werkstoff, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 55, nr 5, 292-292 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To determine some bending strength parameters of I-beams with triangular flanges and wood-fiber board webs.

  • 22.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Nedbrytningsmekanismer hos trä.: 2. Utomhusexponering av radiella och tangentiella ytor av furu och gran.1997Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Sprickförekomst har undersökts hos radiella och tangentiella furu- och granytor som exponerats utomhus i 33 månader. Inverkan av impregnering och ytbehandling med linolja har också testats.

    Den exponerade ytans orientering i förhållande till årsringarna är den parameter som har i särklass största betydelsen för sprickbildningen. Träslag, impregnerings och linoljebehandling har endast marginell betydelse. Samband mellan provernas densitet och sprickförekomst har inte kunnat påvisas.

    Tangetiella ytor av furu har 13 gånger större spricklängd per areaenhet än radiella ytor. För gran är motsvarande värde 6 gånger. Antalet sprickor och sprickbredden är också större på tangentiella ytor än på radiella ytor.

    Vid undersökning av de exponerade ytorna i ESEM har tydliga tecken på nedbrytning kunnat påvisas. Det skikt av krossade fibrer som fås vid mekanisk bearbetning av trä erroderar bort i ett tidigt skede. Därefter angrips porer och ligninrika områden. Sprickor uppstår i fiberväggar och mellan fibrer.

  • 23.
    Sandberg, Dick
    Högskolan i Kalmar, Institutionen för teknik.
    Process and press for manufacturing glued blocks.1997Patent (Övrig (populärvetenskap, debatt, mm))
  • 24.
    Sandberg, Dick
    Kungliga Tekniska hgöskolan (KTH).
    Radially sawn timber: The influence of annual ring orientation on crack formation and deformation in water soaked pine (Pinus silvstris L) and spruce (Picea abies Karst) timber10.1007/s0010700502241997Ingår i: Holz als Roh- und Werkstoff, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 55, nr 3, 175-182 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work describes deformation and crack formation in sawn timber of pine and spruce after first drying and subsequent cycles of resoaking in water and drying. The influence of annual ring orientation and the occurrence of juvenile wood was determined. In addition, the influence of compression wood, annual ring orientation at the edges of the cross section, the position of the board surface in relation to the pith, and the condition of the board surface i.e. whether wet or dry during resoaking were studied. When timber is exposed to repeated cycles of wetting and drying, warp, viz spring, bow, twist and cup, increases and is greater after the first cycle. The influence of annual ring orientation on spring, bow and twist depends on the type of deformation and on the kind of wood. Generally, the results indicated that timber with vertical and semi (half) vertical annual rings show less deformation (mean values) than plain sawn timber and timber containing pith. Cup is mainly caused by transverse anisotropy and is strongly influenced by the radius of the annual ring. Therefore, timber with vertical annual rings do not show any cup. Spring, twist and, especially bow are strongly influenced by compression wood. Large amount of compression wood in sawn timber increases such deformation. The distance between sawn timber in the log and the pith with surrounding juvenile wood is of vital significance for cracking. During moisture cycling, the amount of boards that develop cracks increased irrespective of their prior location in the cross section of the stem. Timber sawn from near the pith or distinctly containing pith has a higher relative crack length compared to timber sawn away from and lacking pith. In timber exposed to repeated cycles of wetting and drying the crack length increases irrespective of its prior location in the stem.

  • 25.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH Träteknologi.
    Structure and Properties of Scandinavian Timber1997Rapport (Övrig (populärvetenskap, debatt, mm))
  • 26. Kifetew, G
    et al.
    Lindberg, H
    Wiklund, M
    Tangential and radial deformation field measurements on wood during drying1997Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 31, nr 1, 35-44 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a previous study, the deformation field measurement method on wood during drying was described. This paper discusses the deformation field measurement results during drying to 8.2% moisture content on the radial and tangential surfaces. It also attempts to explain the observations by an approximate expression based on earlywood-latewood interaction theory. The deformation on the radial surface varied between -0.7% and 7.5%. The actual measurements on the radial surfaces support previous work. Deformation measurements on the tangential surfaces were between -0.5% and 9.0%. Although the investigations were carried out on gross wood specimens, the results provide an insight into the extent to which local density variation within the early- and latewood layers may influence the magnitude of surface deformation.

  • 27.
    Sandberg, Dick
    et al.
    Kungliga Tekniska Högskolan.
    Wålinder, Magnus
    KTH Träteknologi.
    Wiklund, Martin
    KTH Träteknologi.
    The concept of Value Activation: a better utilization of wood.1997Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A new manufacturing system has been proposed in order to improve the utilization of wood. This concept, called Value Activation, is focused on the basic understanding of wood, and the fact that there are properties that are not fully exploited in conventional wood manufacturing systems to date. The strategy is to activate these inherent properties by a better understanding of the fundamental behaviour of wood, combined with new applied process technology and the development of the required manufacturing systems. One basic idea within this concept is a new sawing pattern called star-sawing, which produces timber with two different shapes, viz., timber with rectangular and triangular cross sections. This method facilitates an efficient production of radially sawn timber with vertical annual rings, and without pith and juvenile wood. Computer simulations and in-practice tests demonstrate a high volume yield for star-sawn timber of pine and spruce. Results also show that shape distortion and crack formation as a result of any moisture change in this timber are minimized. Indentation resistance is higher and in-plane movement lower in radial than in tangential sections. The overall properties and appearance of radially sawn timber are seriously affected by splay knots and the associated fibre disturbance. These defects are often not acceptable in further processing. Accordingly, tests have been performed to remove such defects in star-sawn timber in order to produce knot-free boards and solid wood panels. In this process, the timber is finger-jointed to form knot-free lengths suitable for e.g. ceilings and floors. In addition, such lengths of the triangular timber may be used as raw material to produce high quality solid wood panels (solid laminated wood products) with vertical annual rings.

  • 28.
    Sandberg, Dick
    et al.
    Kungliga Tekniska Högskolan.
    Wålinder, Magnus
    KTH Träteknologi.
    Wiklund, Martin
    KTH Träteknologi.
    The concept of Value Activation:  a better utilization of wood.1997Ingår i: IUFRO, Div. 5 conf: Forest products for sustainable forestry. Pullman, USA, 1997Konferensbidrag (Refereegranskat)
  • 29.
    Sandberg, Dick
    Kungliga tekniska högskolan (KTH).
    The influence of annual ring orientation on strength and dimensional changes during moisture variation in finger joints.1997Ingår i: Holz als Roh- und Werkstoff, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 55, nr 1, 50-50 s.Artikel i tidskrift (Refereegranskat)
  • 30.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Transportprocesser i trä.: Permeabilitet.1997Rapport (Övrigt vetenskapligt)
  • 31.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Utvärdering av sönderdelningsmetod för stjärnsågning.1997Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    En ny sönderdelningsmetod för stjärnsågning har testats. Metoden är utvecklad att kunna tillämpas i industriell skala i en kommersiell produktionslinje. Sönderdelningen kan genomföras med konventionella sågmaskiner efter vissa modifieringar av främst fasthållnings- och matningsanordningar.

    En provsågning med 18 furustockar har genomförts varvid volym- och kvalitetsutbytet har bestämts. Det totala volymutbytet blev 58.8 och 71.7 % med avseende på verklig respektive toppmätt volym.

    Vid tillverkning av defekt- och kvistfria ämnen från trekantsprofilerna erhölls ett volymutbyte på drygt 90 %.

  • 32.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Value Activation: a concept for new applied processing technology star-sawing technique.1997Ingår i: Int. Conf. on Value-Added Wood Processing, Nov. 13-14, Vancouver, BC Canada, 1997, 1-10 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    A new manufacturing system has been proposed in order to improve the utilization of wood. This concept, called Value Activation, is focused on the basic understanding of wood, and the fact that there are properties that are not fully exploited in conventional wood manufacturing systems to date. The strategy is to activate these inherent properties by a better understanding of the fundamental behaviour of wood, combined with new applied process technology and the development of the required manufacturing systems.

    One basic idea within this concept is a new sawing pattern called star-sawing, which produces timber with two different shapes, viz., timber with rectangular and triangular cross sections. This method facilitates an efficient production of radially sawn timber with vertical annual rings, and without pith and juvenile wood. Computer simulations and in-practice tests demonstrate a high volume yield for star-sawn timber of pine and spruce. Results also show that shape distortion and crack formation as a result of any moisture change in this timber are minimized.

    The overall properties and appearance of radially sawn timber are seriously affected by splay knots and the associated fibre disturbance. These defects are often not acceptable in further processing. Accordingly, tests have been performed to remove such defects in star-sawn timber in order to produce knot-free boards and solid wood panels. In this process, the timber is finger-jointed to form knot-free lengths suitable for e.g. ceilings and floors.Inaddition, such lengths of the triangular timber may be used as raw material to produce high quality solid wood panels (solid laminated wood products) with vertical annual rings.

  • 33.
    Holmberg, Hans
    et al.
    KTH.
    Sandberg, Dick
    KTH.
    Volymutbyte vid tillverkning av furulimfog från stjärnsågad trekantsprofil.1997Rapport (Övrigt vetenskapligt)
    Abstract [da]

    Volume yield in manufacturing gluelam board of Scots pine from star-sawn triangular profiles.

    by

    H.Holmberg

    D. Sandberg

    Abstract

    Triangular profiles from star-sawing have been used to produce knot free gluelam boards with radial surfaces and a length of 2.1 m. The volume yield has been evaluated in two different gluelam qualities. One was with finger joints and the other one without finger joints. The material used was 7.78 mtriangular profiles of pine. The quality and dimension was sawfallen. The manufacture of the profiles has been carried out in five steps:

    1. Removal of knots and defects.
    2. Finger jointing of cut pieces.
    3. Planing of triangular profiles.
    4. Clueing of triangular profiles into blocks.
    5. Splitting the blocks into gluelam boards and finishing the surface.

    The measurements comprises all steps except splitting and final finishing. These steps have been simulated theoretically.

    The total volume yield was 53.8 %. In the process three operations were found to be critical for the result. They are: removal of knots and defects, planing and splitting of blocks and finishing. These operations account for more than 93 % of the total loss during manufacturing.

    Removal of knots and defects resulted in 12,8 % loss of volume. 13 % of the manufactured blocks were without knots, defects and finger joints. The average length of the pieces after cutting was 0,41 m.

  • 34.
    Kifetew, Girma
    et al.
    KTH, Träteknologi.
    Sandberg, Dick
    KTH, Träteknologi.
    A Comparsion of Dot-counting and Mercury immersion Methods for Determing Density.1996Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This paper describes two wood density determination techniques, one using the dotcounting and the other Mercury immersion and discuses the correlation between the methods. The paper includes also a short literature survey on some other wood density determination methods.

  • 35. Kifetew, G
    Application of the deformation field measurement method to wood during drying1996Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 30, nr 6, 455-462 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method for measuring the deformation field on small wood specimens during drying using a regular grid pattern is described. Preliminary results showed a large variation in surface deformation in the range 0% to 6.2%. To explain the transverse deformation field on the radial face, the different deformation ranges were related to the macrostructure of wood. The latewood region was responsible for the higher deformation field range, while the earlywood layer explained the lower strain held range. The method described could provide important information regarding the history of a specimen which has not so far considered in previous studies on the dynamic behaviour of wood.

  • 36.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Förbättrade träfönster.: Årsringsorientering, sprickor och kärnved - tre viktiga faktorer för fönstervirkets beständighet.1996Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Denna litteraturundersökning har syftat till att belysa befintlig kunskap om användningen av virke, då främst furu, med stående årsringar i fönster. Därutöver belyses furukärnvedens beständighet ovan mark.

    Furukärnvedens beständighet är bättre än splintvedens på grund av att kärnveden innehåller pinosylvinfenoler. Halten av pinosylvin varierar såval inom det enskilda trädet som mellan olika träd. Vid användning av trä ovan mark tyder många undersökningar på att kärnvedens beständighet ger tillräckligt skydd mot svampangrepp, under förutsattning att konstruktionen i övrigt är gjord så att fuktkvoten normalt ligger på en låg nivå.

    Då virke med stående årsringar används är det viktigt att märgen och den juvenila veden tas bort redan vid sönderdelningen. Orsakerna till detta är flera:

    1. Det kan förekomma så kallade kärnsprickor i det levande trädet som utgör initieringspunkter för fortsatt spricktillväxt vid torkning av det sågade virket.
    2. Den juvenila vedens sämre egenskaper jämfort med normalved, samt krökningen på årsringarna nära märgen gör denna ved olämplig att använda i fönster, på grund av ökad risk för sprickor och formförändringar.
    3. Pinosylvinhalten i furukärnveden är lägre i märgområdet jämfört med i den perifera kärnveden.

    Flera undersökningar pekar på att då trä används i väderexponerade konstruktioner skall stående årsringar användas, dels på grund av att fuktrörelsen minimeras, dels på grund av mindre sprickrisk. De mest väderexponerade ytorna bör vara radiella.

  • 37.
    Olsson, Ann-Marie
    et al.
    STFI.
    Sandberg, Dick
    KTH, Träteknologi.
    Modern adhesion theory applied on coating and gluing of wood.: Analysis of the interaction between wood and high solid linseed oil paint.1996Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This work describes the requirements for the interaction between wood and linseed oil paint

    with regard to "modem adhesion theory", i.e. known as Lewis acid-base theory. After a short

    introduction about linseed oil as binder in paint, results from an investigation of the surface

    tension properties for linseed oil will

    bepresented. Finally, the total interaction between linseed

    oil paint and wood will be discussed.

  • 38.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Produktion och provning av radialsågat trä: slutrapport1996Rapport (Övrigt vetenskapligt)
  • 39.
    Sandberg, Dick
    et al.
    Kungliga tekniska högskolan (KTH).
    Holmberg, Hans
    KTH.
    Radially sawn timber: Knots - number, type and size in star-sawn triangular profiles of pine (Pinus silvestris L) and spruce (Picea abies Karst)1996Ingår i: Holz als Roh- und Werkstoff, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 54, nr 6, 369-376 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes the appearance and number of knots in star-sawn triangular profiles of pine (Pinus silvestris L) and spruce (Picea abies Karst). The emphasis is placed on obtaining the volume yield of boards with a given knot appearance, together with the sizes of the fibre disturbances around the knots and how they affect the yield. The test material has been taken from three regions in Sweden and is made up of butt logs of pine and of normal and fast-growing spruce. The results show that a large proportion of the knots found in the triangular profiles from butt logs are unacceptable in further refinement of the timber and must be removed. Very few healthy knots can be found. To produce knot free boards, a volume reduction of on average 8 and 21 percent is obtained for pine and spruce respectively, calculated with respect to the original profile volume. If the fibre disturbance around the knots is also removed, a further volume loss of 5 percentage for pine and 6 percentage for spruce is obtained. The boards produced have a broad spectrum of lengths between 2 and 500 centimetres for pine and between 2 and 400 centimetres for spruce.

  • 40.
    Sandberg, Dick
    Kungliga tekniska högskolan (KTH).
    Radially sawn timber.: Star-sawing - a new method for produring timber with vertical annual rings.1996Ingår i: Holz als Roh- und Werkstoff, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 54, nr 3, 145-151 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work presents a new method of sawing to produce pith-free timber with vertical annual rings and without juvenile wood. The method, which is called star-sawing, gives sawn timber with two different shapes, viz, conventional timber with a rectangular cross-section and timber with a triangular cross-section. The volume yield for star-sawing has been determined with the help of computerized simulations and trial sawings. The results show that star-sawing is best suited for logs with a top diameter greater than 200 millimetres. Both a high volume yield and suitable dimensions of the sawn timber were then obtained. The volume yield of timber with vertical annual rings in star-sawing is about 0.70 calculated with regard to the top cylinder volume under bark.

  • 41. Kifetew, Girma
    Some aspects on the deformation behaviour of wood in relation to its structure1996Bok (Övrigt vetenskapligt)
  • 42.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    The influence of pith and juvenile wood on proportion of cracks in sawn timber when kiln dried and exposed to wetting cycles.1996Ingår i: Holz als Roh- und Werkstoff, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 54, nr 3, 152-152 s.Artikel i tidskrift (Refereegranskat)
  • 43.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Trätradition med ny teknik.: värdeaktivering med stående årsringar 1996.1996Rapport (Övrig (populärvetenskap, debatt, mm))
  • 44.
    Carlsson, Staffan
    et al.
    KTH Träteknologi.
    Eskilander, Stephan
    KTH Träteknologi.
    Sandberg, Dick
    KTH, Träteknologi.
    Utvärdering av deplacementmetod med vatten för bestämning av träets torrdensitet.1996Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Evaluation of the deplacement method with water for determination of dry wood density.

    by Staffan Carlsson, Stephan Eskilander and Dick Sandberg

    Abstract

    A new method (SP-method) for determination of wood density at 12 % moisture content has been developted at the Swedish National testing and Research Institute (SP). The method is a futher development of the deplacement method with water as. The volume of the specimens is determined with use of Archimeds principle. The specimen is immersed in water and a computer program compensate for errors in the measurement as a result of wateruptake in the specimen.

    This investigation describes the correlation between the dry density of wood, determined by the SP-method and a "traditional" method. Traditional method means that the dimensions of the specimen are measured with a slide-calliper in order to calculate the volume of the specimen. The test materials were taken from Scots pine and Norway spruce with dimension 40 x 60 x 120 mm.

    The results show a difference less than 3 % between dry density determined by the two methods. The correlation coefficient (R2) was 0.99 when linear regression was used. Repetition test showed mean deviation of 0.2 % when dry density for same specimens were determined two times with the SP-method.

  • 45.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH.
    Volym- och kvalitetsutbyte vid stjärnsågning.1996Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Volume yield and quality of timber when using Star-sawing technique

    by

    Hans Holmberg and Dick Sandberg

    Abstract

    Volume yield and quality are investigated when starsawing logs of pine (Pinus silvestris L) and spruce (Picea abies Karst). Topdiameters of timber were for pine sorted in two classes 260-300 rnm and 300-340 mm. Spruce timber were sorted in one class with top diameters between 290 and 340 mm.

    The investigation shows a volume yield considerably higher for starsawing compared to conventional techniques. This investigation, carried out on a simple testplant, yields 68 %calculated from top volume of log. Volume yield calculated from a cone with top and root diameters is 56 %. With sideboards included these numbers will incerease with one percent. The triangular profiles is 47 % of the total volume and the rest 53 % are quarter sawn boards.

    The volume yield of spruce is about one percent higher than for pine. The difference is assumed to depend on more pronounced taper of the log in spruce, wich allows easier positioning of the log.

    Quality is determined with a method developed especially for quarter sawn timber.

     

  • 46.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH.
    Diagrambilaga till Rapport KTH-Trä TRITA-TRÄ R-95-12.1995Rapport (Övrigt vetenskapligt)
  • 47.
    Sandberg, Dick
    et al.
    Kungliga Tekniska Högskolan.
    Johansson, Ingvar
    KTH Träteknologi.
    Kvarstående deformation hos furu efter böjbelastning under samtidig fuktvariation.1995Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    I detta arbete undersöks den kvarstående deformationen hos små provkroppar av furu (Pinus silvestris L) som utsatts för böjbelastning och samtidig cyklisk varierande fuktkvot. Två provgrupper har undersökts, dels prover belastade radiellt årsringama, dels prover belastade tangentiellt årsringarna. Efter avlastning uppfuktades provkroppama i vattenbad varefter de åter fick torka och återhämtningen bestämdes. Återhämtning har definierats som skillnaden i utböjning före och efter uppfuktning och torkning i förhållande till utböjningen före uppfuktning. Provema har även undersökts i svepelektronmikroskop (SEM).Resultaten visar att återhämtningen var omkring 80 % oberoende av belastningsriktning. Detta bekräftar att stor del av den krypdeformation som erhölls vid fuktcykling under belastning är reversibel. SEM-studien visar att brott uppstår i cellväggama vid mekanosorptiv krypning under relativt måttlig belastning, 30 procent av böjbrottgränsen vid 12 % fuktkvot, och att skadornas karaktär är beroende av belastningsriktningen i förhållande till årsringsorienteringen

  • 48.
    Holmberg, Hans
    et al.
    KTH Träteknologi.
    Sandberg, Dick
    KTH Träteknologi.
    Kvistars frekvens, form och beskaffenhet i trekantprofil av furu (Pinus silvestris L) och gran (Picea abies Karst).1995Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Frequency and Character of Knots in Triangular Profiles of Pine (Pinus silvestris L) and Spruce (Picea abies Karst).

    by

    Hans

    Holmberg Dick Sandberg

    Abstract

    This report describes the structure and amount of knots in triangular profiles from StarSawing of pine (Pinus silvestris L) and spruce (Picea abies Karst). The yield of blanks is determined mainly with a defined knot structure and the fibre aberration around knots. In addition a minor investigation of the amount of pitch pockets has been carried out.

    The specimens comprise of butt logs from three different areas in Sweden. The specimens are taken from normal grown pine, and both normal and fast grown spruce.

    Large amounts of the knots found in triangular profiles from butt logs are unacceptable for further refinement. Thus, the knots have to be removed. When producing blanks free from knots there is a volume decrease of 8 and 21 percent in average for pine and spruce respectively, referring to the original volume. Further refinement including fibre aberration increases the volume loss by another 5 percent for pine and 6 percent for spruce. The length of the refined blanks varies between 2 and 500 centimetres for pine and between 2 and 400 centimetres for spruce.

    Measurement results are included in the report for calculating the volume yield of blanks free from knots, with or without fibre aberration. The distributions of lengths of blanks and corresponding volume yields are shown in different graphs.

  • 49.
    Sandberg, Dick
    Kungliga Tekniska Högskolan.
    Nedbrytningsmekanismer hos trä: fotokemisk nedbrytning1995Ingår i: Nedbrytningsmekanismer och livslängd hos byggnadsmaterial: Doktorandkurs i byggnadsmateriallära 1994, Stockholm: KTH Royal Institute of Technology, 1995, , 14 s.1-14 s.Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [sv]

    En litteraturstudie över fotokemisk nedbrytning av trä har genomförts. Såväl nedbrytningen av de enskilda beståndsdelarna i träet, det vill säga cellulosa, hemicellulosa, lignin och en flertalextraktivämnen, som av den makroskopiska träsubstansen, har behandlats. Till skillnad från många av de litteraturstudier som tidigare har utförts inom detta område, har tonvikten inte lagts på de kemiska reaktionerna som sker då trä exponeras för elektromagnetisk strålning, utan mer på själva träets nedbrytning på makroskopisk nivå. Skillnader i nedbrytningsmönster mellan virke med stående respektive liggande årsringar har också belysts

  • 50.
    Sandberg, Dick
    Kukngliga Tekniska Högskolan.
    Stående årsringar hos furu (Pinus silvestris L) och gran (Picea abies Karst).1995Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Vertical annual rings can be obtained from radially sawn timber. Compared to other annual ring directions timber with vertical annual rings have a number of advantages, like it is less susceptible to crack during drying and the moisture movements are uniform.

    In this study a definition of vertical annual rings has been proposed. The definition is based on condition that the moisture movement of the width should not exceed ten percent, as a result of deviation from exactly vertical annual rings. According to the developed definition pine (Pinus silvestris L) and spruce (Picea abies Karst) are considered to have vertical annual ringsifthe angle between the flat side and the tangent to the annual ring at half the thickness is between 60 and 90 degrees. To avoid surface cracks one should take particular attention on the annual ring orientation in the surface of lumber with thicker dimensions.

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