WOOD AND TIMBER - Click here to return to overview or click on a title to download the document A dynamic approach to assess the modulus of elasticity in wood decay testing Authors: L. Machek, H. Militz, R. Sierra-Alvarez Language: English In this study, the changes in elastic behaviour and mass losses of different hardwood and softwood species exposed to decay in a laboratory soil tests were assessed. Wood decay was monitored using different assessment methods, namely: mass loss and changed in elastic behaviours (MOE) determination. Elastic changes were determined by static and dynamic methods, fot the latter acoustic technique was applied. The results obtained show a high correlation between dynamic and conventional static bending measurements of test specimens at different stages of wood decay. The non-destructive assessment of modulus of elasticity assessment proved to be a good tool in the prediction of early stages of wood decay. Biological attack of acetylated wood Authors: Mohebby Behbood Language: English Acetylation is an environmental friendly method to modify wood properties and protect it against biological attack. Many researches have been done in this field. However, no concern was paid for mode of protection in acetylated wood. This research had been aimed to study mode of action in acetylated wood by investigating on weight and MOE loss, chemical alteration in cell wall due to microbial attack, IRspectroscopy, microcalorimetry, determination of fungal biomass by using ergosterol assay and FDA hydrolysis and enzyme assays. Beech and Scots pine wood samples were acetylated by using acetic anhydride at temperature 80-120°C for 180min. Acetylated wood samples were tested under soil bed test condition, field and basidiomycete trials. Results showed that the losses of weight and MOE decreased at increasing weight gains. Soil bed test revealed that the acetylation of beech wood at above 8% and pine wood at above 10% inhibits soil microorganisms in attacking wood and their activities reached to nil at higher weight gains. A test with the white rot fungus (T. versicolor) showed that the weight loss decreased at raising weight gains. Weight gains of above 10% inhibited fungal decay in beech wood and it reached to zero at higher weight gains. Microscopical studies of wood from soil bed samples, field trials and basidiomycete (white- and brown-rot) tests showed that fungi could colonize acetylated and non-acetylated wood. However, measurements of fungal biomass by using ergosterol assays in those woods and fluorescein diacetate in white rottests showed a rapid colonization of fungal hyphae at early stages of incubation and decreased amount of fungal biomass at raising weight gains. Results showed that fungal colonization is influenced by the acetylation. Biological activities were measured in wood by using microcalorimetry. The reduction of thermal powers and measured amounts of energy production in acetylated wood revealed that activities of microorganisms were influenced by the acetylation and their activities decreased at increased degree of the acetylation. Microscopy of field trial samples showed that the acetylation of wood was affected the growth of soil microorganisms and protected wood against soil microorganisms during a long period of exposure (350 weeks) to soil. Different types of decay in field samples showed successional activities of soft- and white-rot fungi and also bacteria. Soil bed test showed a synergism between soil fungi and bacteria in wood. It was revealed that bacteria followed hyphal traces in cells and associated with fungi in wood degradation. Chemical analyses of acetylated wood in soil bed samples showed a significant effect of the acetylation on removal of cell wall components. The analyses showed a reduction in removal of cell wall components at increased weight gains. Results revealed that removal of the cell wall components reduced considerably in beech wood at weight gains above 8% and in Scots pine samples at above 10%. Study on patterns and phenol ogy of white- and brown-rot decay on acetylated wood showed no difference of decay patterns between acetylated and non-acetylated wood, however decay patterns appear more later in acetylated wood. Combined investigation: assessment of the effectiveness of national and European roundwood and sawn timber grading systems Authors: University of Aberdeen Language: English The main objective of the study was to ascertain whether there was any correlation between outer stem characteristics (mainly different types of branches) and the quality of the sawn material produced (knot structure etc.). These "quality" characteristics were expressed using a number of national and European grading systems and therefore the study was as much an assessment of the usefulness of the grading systems as it was about tree physiology. Ein neues Messverfahren zur Bestimmung des Elastizitätsmoduls von Holz, Authors: R. Görlacher, Versuchanstalt für Stahl, Holz und Steine der Universität Karlsruhe Language: German In der Holzforschung und bei der Materialprüfung fehlt bisher ein anerkanntes Verfahren zur zeitsparenden und zuverlässigen Bestimmung der Elastizitätsmoduls von Hölzern unterschiedlicher Abmessungen. Ein ursprunglich für isotrope Werksoffe entwickeltes Meßverfahren zur Bestimmung des dynamischen Elastizitätsmoduls konnte durch Modifizierung der Berechnungsweise auch auf den Werkstoff Holz übertragen werden. Drei systematische Versuchsreihen zur Erprobung des Meßverfahrens und seiner Auswertung wurden durchgeführt. Einfluß unter unterschiedlicher behandlungsmodelle auf Verwertung und Verarbeitung von Eschenschnittholz Authors: Manfred Quer Language: German Entwicklung einer automatischen Qualitätskontrolle von Fichtenholzleisten in der laufenden Produktion (Auszug), Authors: Miko Vrielmann, Fachhochschule Rosenheim, Fachbereich Holztechnik Language: German Etude comparative de deux méthodes de détermination du module d'élasticité du bois et de ses dérives, Authors: Lecomte, Croisset Language: French Karakterisatie en sterktesortering van inlands vurenhout, Authors: Ir. H. Coppens, Rijksuniversiteit Gent, Faculteit van de Landbouwwetenschappen, Laboratoria voor Plantecologie en voor Houttechnologie Language: Dutch Klassifizierung von Brettschichtholzlamellen durch Messung von Longitudinalschwingungen, Authors: R. Görlacher, Versuchsanstalt für Stahl, Holz und Steine der Universität Karlsruhe Language: German Master's Thesis - Non-destructive testing of particleboard with ultra sound and eigen frequency methods Authors: Fredrik Grundström Language: English In the production of particleboard, different properties of the board have to be measured in order to keep the board quality within required limits. Non-destructive methods for this purpose include ultra-sonic testing and eigen frequency testing. These methods have been proposed for measuring the strength of the board after pressing, for process control purposes. The ultra sound velocity and eigen frequency have been proved to be good instruments for doing this. The results show that Young's modulusand bending strength can be predicted with high accuracy with these methods. Internal bond can only be predicted with poor to fair accuracy with normal regression models. The use of multivariate models most often give better predictions of the internal bond. Multivariate models are best suited for complex predictions if the prediction variables are weak. Mechanische sterktesortering, Authors: Ir. Coppens, TCHN Language: Dutch De "mechanical stress grading" is een storingsvrije test die oorspronkelijk gebaseerd was op de dynamische (in doorloop) bepaling van de E-modulus. Recentere ontwikkelingen maken geen gebruik van doorbuiging, maar geven waarden die rechtstreeks gecorrelleerd zijn met het bestudeerde kenmerk. Mechanische sterktesorteringsmachines kunnen verscheidene aspecten van het hout in rekening nemen zoals kwasten, scheuren, vezelverloop of fysische em mechanische karakteristieken zoals de dichtheid en de elasticiteitsmodulus. Nieuwe methodes om houtgebreken op te sporen : Ultra-geluid en de eigenfrekwentiemethode openen nieuwe perspektieven bij het kontroleren van volhout en spaanderplaten. Language: Dutch Spaanplatenonderzoek : trilling verraadt sterkte Authors: WTCH Language: Dutch Het technisch centrum der Houtnijverheid startte ongeveer 4 jaar geleden een onderzoeksproject onder de titel "kwaliteitscontrole van Spaanplaten door de meting van hun trillingsgedrag". Men is nu aan besluiten toe. Blijkbaar is de kans reëel dat men in de spaanplatenproduktie inderdaad een snelle methode voor kwaliteitscontrole kan ontwikkelen. Het onderzoek heeft daarmee zijn doel bereikt. Technologische Holzeigenschaften der Douglasie (Pseudotsuga menziesii (Mirb.) Franco) als Ausprägung unterschiedlicher Wachtumsbedingungen Authors: Udo Hans Sauter, Forstwissenschaftlichen Fakultät der Albert-Ludwigs-Universität zu Freiburg im Breisgau Language: German The influence of wood moisture content on dynamic modulus of elasticity measurements in durability testing Authors: L. Machek, H. Militz, R Sierra-Alvarez Language: English The use of an acoustic technique to assess wood decay in laboratory soil-bed tests Authors: L. Machek, H. Militz, R. Sierra-Alvarez Language: English This study assesses the changes in elastic behaviour (i.e. modulus of elasticity -MOE) and mass loss of different hardwood and softwood species exposed to decay in laboratory soil-bed tests. Elasticity moduli were determined using conventional static methods as well as a dynamic method based on flexural vibration. The results obtained show a high correlation between dynamic and static bending measurements for all the timber species tested at different stages of fungal decay. Furthermore, the non-destructive MOE assessment proved to be a good tool for the early detection of wood decay. Untersuchung eines dynamischen Meßverfahrens zur Bestimmung des Elastizitätsmoduls (E-modul) von Spanplatten-Probekörpern sowie Untersuchungen über den Zusammenhang zwischen E-modul und Festigkeitseigenschaften von Spanplatten-Probekörpern. Language: German Vorrichtung zur maschinellen Festigkeits-Sortierung von Schnittholz Authors: Fagus Grecon Greten GmbH & Co Language: German Optimising the use of sawn timber for structural purposes Vorrichtung zur maschinellen Festigkeitssortierung von Schnittholz Authors: H. Röse, P.Kosel, P.Sobisch Language: German

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