20.500.12556/RUL-108269 Ojačitev slojnatega furnirnega lesa (LVL) Reinforcement of laminated veneer lumber (LVL) Lepljeni konstrukcijski elementi iz lesa morajo imeti ustrezne mehanske lastnosti. Za širšo uporabo v praksi je aktualno tudi izboljšanje njihove upogibne trdnosti in togosti. V ta namen smo mehanske lastnosti slojnatega furnirnega lesa (LVL) izboljševali s sintetičnimi vlakni, ki smo jih dodajali v lepilne spoje. Pri preizkusih smo uporabili bukov furnir, poliuretansko lepilo ter epoksidno lepilo in sintetična vlakna. Ta so bila ogljikova, kevlarjeva ter steklena, ki smo dodajali v obliki pletene mreže v zunanja dva lepilna sloja LVL in jih zlepili v ploščo. To smo razžagali in dobili preizkušance, pri katerih smo ugotavljali modul elastičnosti z nedestruktivno in destruktivno metodo. Najprej smo pri preizkušancih merili hitrost preleta ultrazvoka, nato pa smo še statične meritve opravili s tritočkovnim upogibnim testom. Ugotovili smo, da se modul elastičnosti furnirnega lesa najbolj poveča z dodajanjem ogljikovih vlaken. Kombinacije lepila in vlaken so sicer različno vplivale na izboljšanje upogibne togosti in trdnosti LVL. Preizkušanci lepljeni s poliuretanskim lepilom so izkazovali boljše trdnostne lastnosti, kot preizkušanci lepljeni z epoksidnim lepilom. Večja kot je bila gramatura ojačitvenih vlaken, večja je bila tudi ojačitev preizkušanca pri posamezni vrsti vlaken. Glued structural elements of wood must have the appropriate mechanical properties. For wider application in practice, it is also important to improve their bending strength and rigidity. For this purpose, the mechanical properties of laminated veneer lumber (LVL) were improved with synthetic fibres, which were added into bonding layer of LVL. In the experiment, we used beech veneer, polyurethane and epoxy adhesives and synthetic fibres. We used carbon fibres, aramid and glass fibres. Reinforcement was added in the form of knitted nets in the two outer adhesives layers of the LVL and glued to the plate. The plate was then cut and experiments carried out to determine the modulus of elasticity using non-destructive and destructive methods. For the first technique we measured the speed of ultrasound along the specimens to determine dynamic modulus of elasticity, and followed by static mechanical three-point bending test. The greatest increase in the modulus of elasticity was achieved with adding of carbon fibres. The adhesive and fibre combinations have had different impacts on the improvements in bending stiffness and strength. The specimens glued with the polyurethane adhesive showed better strength properties than those made with epoxy adhesive. The more reinforcement fibres were used, the greater the stiffness of the tested specimens. slojnat furnirni les vlakna epoksi poliuretan upogibna trdnost modul elastičnosti laminated veneer lumber fibre epoxy polyurethane bending strength modulus of elasticity true false false [B. Gošnjak] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2019-06-23 07:45:04 2019-06-23 07:45:13 2022-08-20 03:45:27 0000-00-00 00:00:00 2019 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 630*832.286:630*824.839 163885 3065993 6948.pdf 6948.pdf 1 0933F72B6FD1D2E3207F542123BEADEB 3f55fa31259896978ee859ab5a82b8da10e7890df00ad8212fdd573209a02638 9ba40c4e-a1b6-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=119217 Biotehniška fakulteta 0 0 0