500 KB35 KB199820242017Straže, AlešŽveplan, Ervinštevilka:2letnik:66str. 5-14ISSN:0024-1067COBISSID_HOST:2845577URN:URN:NBN:SI:doc-5PFL3Z9KslBiotehniška fakulteta, Oddelek za lesarstvoLes (Ljubljana)acoustic characteristicsakustične lastnostibeechbukevFagus sylvaticahidrotermična obdelavahydrothermal treatmentlesmechanical propertiesmehanske lastnostiwoodAkustične lastnosti bukovine po hidrotermični obdelavi| Acoustic properties of beech wood after hydrothermal treatment|We investigated the acoustic properties of beech wood (Fagus sylvatica L.) after hydrothermal treatment. Two beech logs were cut into 10 pairs of radially oriented specimens with the dimensions 500 mm % 160 mm % 12 mm and air dried. Specimens were thermally treated for 1 hour in saturated vapour pressure atmosphere at 135 °C. After the treatment the specimens were conditioned at 20 °C and 50 % RH and their wood density, speed of ultrasound in all directions and colour properties in CIELab colour space were determined. Free flexural vibration tests were used afterwards to determine the acoustic properties of wood. We defined acoustic coefficient (K), damping of sound (tan ?\delta$?) and relative acoustic conversion efficiency (RACE). The study confirmed a significant decrease of wood density after the hydrothermal processing. The increase in speed of ultrasound in hydrothermally-treated wood caused no change in the modulus of elasticity in all anatomical directions. Mechanical anisotropy of wood decreased slightly after the treatment. The colour measurements of specimens showed a linear correlation between the total colour change and change of wood density and stiffness. The acoustic properties of hydrothermally treated beech wood were partly improved due to the increase in the specific modulus of elasticity and the acoustic coefficient combined with the decrease in vibration dampingRaziskali smo akustične lastnosti bukovine (Fagus sylvatica L.) po hidrotermični obdelavi. Iz dveh bukovih hlodov smo izžagali 10 parov radialno orientiranih preizkušancev nominalnih dimenzij 500 mm % 160 mm % 12 mm ter jih naravno posušili. Preizkušance smo 1 uro tretirali v nadtlačnem hidrotermičnem procesu pri temperaturi 135 °C. Po uravnovešenju pri 20 °C in 50 % zračni vlažnosti smo preizkušancem določili gostoto, hitrost preleta ultrazvoka v posameznih anatomskih smereh ter barvo po CIELab sistemu. Pri impulznem prečnem mehanskem vzbujanju smo določili še kazalnike akustične kakovosti. Določili smo akustični koeficient (K), dušenje zvoka (tan ?\delta$?) in relativno učinkovitost akustične pretvorbe (RACE). Po hidrotermični obdelavi smo potrdili zmanjšanje gostote bukovine ter povečanje hitrosti zvoka in togosti v vseh anatomskih smereh. Mehanska anizotropija lesa se je po obdelavi zmanjšala. Celotne barvne spremembe so bile značilno linearno povezane s spremembo gostote in s tem ohranitvijo togosti bukovine. Kazalniki akustične kakovosti hidrotermično obdelane bukovine so se delno izboljšali. Potrdili smo višji specifični modul elastičnosti in akustični koeficient ter manjše dušenje prečnega nihanja hidrotermično obdelanega lesaTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaZveza lesarjev Slovenije