20.500.12556/RUL-158859 Primerjava izbranih lastnosti lesa beljave in jedrovine pri hrastu diplomsko delo - visokošolski strokovni študij Comparison of selected properties of oak sapwood and heartwood graduation thesis - higher professional studies V Sloveniji se dobavitelji masivne hrastovine pogosto soočajo s prepričanjem uporabnikov, da je les beljave manj trden oz. ima slabše mehanske lastnosti kot les jedrovine. Cilj raziskovalne naloge je bil preučiti osnovne mehanske lastnosti lesa beljave in jedrovine vrste hrastov, ki se največ pojavljajo na slovenskem tržišču. Vzorce smo odvzeli iz 26 hrastovih hlodov, pripravljenih za izdelavo železniških pragov, od katerih je bilo 16 hlodov (62 %) iz skupine belih hrastov (Quercus robur ali Quercus petraea) in 10 hlodov (38 %) iz skupine rdečih hrastov (Quercus cerris). Na vzorcih beljave in jedrovine smo izmerili upogibno trdnost in modul elastičnosti (MOE), tlačno trdnost, trdoto po Brinellu in gostoto. Primerjave merjenih lastnosti med posameznimi kategorijami lesa so razkrile, da ni tipičnih razlik med lastnostmi lesa beljave in jedrovine, pokazale pa so se statistično značilne razlike med lastnostmi lesa belega in rdečega hrasta. Rezultati tako zavračajo laično mnenje uporabnikov, da so mehanske lastnosti lesa beljave slabše kot lastnosti lesa jedrovine. Raziskave so tudi pokazale, da ima zaradi variabilnosti les cera lahko celo boljše mehanske lastnosti kot les doba ali gradna. Tudi to je v nasprotju s splošnim mnenjem, da so lastnosti lesa rdečih hrastov slabše kot lastnosti lesa belih hrastov. Rezultati raziskave bodo prispevali k boljšemu razumevanju variabilnosti lastnosti lesa in optimalnejši izbiri in uporabi hrastovine. Oak wood suppliers in Slovenia are often confronted with belief of consumers, that sapwood is less solid therefore has weaker mechanical properties than heartwood. The aim of this research was to investigate basic mechanical properties of sapwood and heartwood of oaks that appear most frequently on Slovenian market. We take samples of 26 oak logs prepared to be treated into railway sleepers, from which 16 logs (62 %) were from white oak (either Quercus robur and Quercus petraea) and 10 logs (38 %) were from red oak (Quercus cerris). On samples of sapwood and heartwood bending strength, module of elasticity (MOE), compression strength, Brinell hardness and density were measured. Comparison of measured properties discovered that there are no typical differences between individual categories of oak wood, but showed the statistically significant difference between qualities of white and red oak wood. The results declined the laic opinions of consumers, that mechanical properties of sapwood are worse than mechanical properties of heartwood. The research also showed, that due to variability, the Turkey oak (Quercus cerris) wood could possibly have even better mechanical properties than pedunculate oak (Quercus robur) or sessile oak (Quercus petraea), which is also in contrast with general opinion that characteristics of red oak wood are worse than white oak wood. Results of the research will contribute to better understanding of wood properties variability and more optimal selection and usage of solid oak wood. beljava jedrovina mehanske lastnosti hrastovina sapwood heartwood mechanical properties oak true false false R. Keše Slovenski jezik Angleški jezik Diplomsko delo 2024-06-21 11:43:25 2024-06-21 11:43:28 2024-07-05 03:40:39 0000-00-00 00:00:00 2016 0 Ljubljana 2016 Ljubljana XI, 54 f., [5] f. pril. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 630*811.5 2627721 UNI_Kese_Rok_2016.pdf UNI_Kese_Rok_2016.pdf 1 94EAC4A79A1672AF1A73CB49714A362E 3eb997876182025cf27631fb458330897b4a43164e38d6bd8efec8b735cb36ea b8595714-2fb2-11ef-a25b-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=186588 Biotehniška fakulteta 0 0 0