20.500.12556/RUL-107402 Mehanske lastnosti starega hrastovega konstrukcijskega lesa MECHANICAL PROPERTIES OF OAK WOOD FROM HISTORICAL CONSTRUCTIONS Raziskali smo gostoto ter nekatere mehanske lastnosti povezane s staranjem lesa. Vzorčili smo hrastov (Quercus spp.) konstrukcijski les starosti od 4 let do 512 let z znanimi dendrokronološkimi podatki. Na 31 izbranih kolutih stare hrastovine smo v laboratorijskih pogojih izmerili v vseh anatomskih smereh lesa hitrost preleta ultrazvoka ter togost lesa. S statičnimi testi smo preverili še trdoto prečno na vlakna ter strižno trdnost vzporedno z vlakni. Glede na starost lesa smo ugotovili neznačilne spremembe gostote lesa, strižne trdnosti lesa, hitrosti ultrazvoka ter dinamične togosti v vseh anatomskih smereh hrastovine. Največjo togost hrastovega lesa smo določili vzporedno z vlakni, 4-krat manjšo pa v radialni in tangencialni smeri. Trend počasnega zmanjševanja vrednosti s staranjem hrastovine, vendar statistično neznačilen, smo ugotovili pri trdoti lesa prečno na vlakna, v radialni in tangencialni smeri. Tudi specifična trdota, kot razmerje trdote in gostote lesa, je bila pri stari hrastovini nekoliko nižja kot pri recentnem hrastovem lesu. The density and some mechanical properties associated with the ageing of wood were investigated. We have sampled oak construction wood (Quercus spp.) from four years to 512 years old with known dendrochronological data. On 31 selected discs of old oak, the speed of ultrasound and the stiffness of the wood in all anatomical directions of wood were measured in laboratory conditions. With static tests, the hardness transverse to the grain and the shear strength parallel to the grain were tested as well. Depending on the age of the wood, uneven changes in the density of wood, shear strength of the wood, the speed of ultrasound and dynamic stiffness in all anatomical directions of wood have been observed. The highest stiffness of oak wood was determined parallel to the grain. Similar results, but four times smaller, were determined in the radial and tangential directions. The trend of a slow decrease in value with oak aging that is statistically insignificant was found in the hardness of the wood transverse to the grain, and in radial and tangential directions. The ratio of hardness and density of the wood, known as the specific hardness, was somewhat lower in the old oak than the recent oak wood. les hrast staranje mehanske lastnosti wood oak ageing mechanical properties true false false [Ž. Kavčič] Slovenski jezik Angleški jezik Diplomsko delo/naloga 2019-04-11 07:45:15 2019-04-11 07:45:17 2022-08-19 03:49:21 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*812 163597 3027849 6747.pdf 6747.pdf 1 9670F9F4025536E703F849976E2625E5 0d5272a29d009e9ca5a2d5220983d5c613c7b274cffbf5716a378e8eecf5cb60 6c8fd6c6-a1b6-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=118217 Biotehniška fakulteta 0 0 0