20.500.12556/RUL-173392 Proučevanje vpliva vlažnosti lesa na dielektrične in dinamične mehanske lastnosti hrastovine Investigation of the effects of moisture content on the dielectric and dynamic mechanical properties of oak wood Diplomsko delo obravnava proučevanje vpliva vlažnosti lesa hrasta gradna (Quercus petraea) na njegove dielektrične in dinamične mehanske lastnosti. Raziskovalno delo je potekalo na tankih lamelah, ki so bile bodisi osušene do absolutno suhega stanja, uravnovešene pri temperaturi 20 °C in pri različnih relativnih zračnih vlažnostih (33 %, 65 % in 85 %) oz. parjene v komori pri 90 °C z nasičeno vodno paro. Najprej smo opravili preizkus dinamičnih mehanskih lastnosti z opremo za določanje frekvenčnega odziva ob impulzivnem mehanskem vzbujanju v prečni smeri na smer poteka lesnih vlaken. Nato smo nadaljevali s preizkušanjem dielektričnih lastnosti, katere smo opravljali pri sobni temperaturi v frekvenčnem območju elektromagnetnega polja od 79 kHz do 25,119 MHz. Ugotovili smo, da z višanjem vlažnosti lesa njegov dinamični modul elastičnosti (E) upada. Z višanjem vlažnosti lesa padajo tudi vrednosti merjenih akustičnih parametrov (R, ACE in RACE), medtem ko dušenje mehanskega nihanja (tanζ) narašča. Ugotovili smo, da z naraščanjem vlažnosti lesa in frekvence elektromagnetnega polja njegova dielektrična vrednost (ε) in faktor izgub (tanδ) naraščata. Izjema je bil le les, ki je bil izpostavljen parjenju pri višji temperaturi in se mu je vlažnost lesa hitro zniževala. The diploma thesis deals with the study of the influence of moisture content of pedunculate oak (Quercus petraea) wood on its dielectric and dynamic mechanical properties. The research work was carried out on thin lamellas that were either dried to an absolutely dry state, equilibrated at a temperature of 20 °C and at different relative air humidities (33 %, 65 % and 85%), or steamed in a chamber with water saturated steam at 90 °C. First, we performed a test of dynamic mechanical properties with equipment for determining the frequency response to impulsive mechanical excitation in the transverse direction to the direction of wood fibers. Then we continued with testing the dielectric properties, which was performed at room temperature in the electromagnetic field frequency range from 79 kHz to 25.119 MHz. We found that as the moisture content of wood increases, its dynamic modulus of elasticity (E) decreases. As the moisture content of wood increases, the values of the detected acoustic parameters (R, ACE and RACE) also decrease, while the damping of mechanical vibrations (tanζ) increases. We found that as the moisture content of wood and the frequency of the electromagnetic field increase, its dielectric constant (ε) and loss factor (tanδ) increase. The only exception was wood that was exposed to steaming at a higher temperature, for which its moisture content decreased rapidly. hrast les dielektrične lastnosti dinamične mehanske lastnosti preizkus oak wood dielectric properties dynamic mechanical properties test true false false [A. Hribar] Slovenski jezik Angleški jezik Diplomsko delo/naloga 2025-09-17 07:18:03 2025-09-17 07:18:05 2025-11-08 03:54:08 0000-00-00 00:00:00 2025 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 630*812 264667 249231363 52213.pdf 52213.pdf 1 042B91EC7A86202C5BE5BE6A49F65D39 7c841e71ec51ae61a2f747047e89a1cd35059ef80d724902fe5d7a167c008d68 849d9c10-9385-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=217802 Biotehniška fakulteta 0 0 0