20.500.12556/RUL-158937 Analiza odzivnosti ivernih plošč z različnim deležem zunanjega sloja na mehanske obremenitve Analysis of the response of particleboard with different surfce layer on mechanical loading Iverne plošče so ključnega pomena v lesarstvu in si brez njih težko predstavljamo sodobno industrijo, saj odsluženemu lesu ali hlodovini slabše kakovosti dodajo nov pomen. Sama uporabnost ivernih plošč je odvisna od številnih dejavnikov, med pomembnejšimi je struktura plošče, predvsem razmerje med finejšimi frakcijami v zunanjih slojih in srednjih iveri v notranjem. Kljub simetričnosti ivernih plošč se opazi razliko med zgornjo in spodnjo stranjo, kar posledično vpliva na lokacijo nevtralne osi in upogibno trdnost. Da bi ugotovili korelacijo med lokacijo nevtralne osi in upogibno trdnostjo ivernih plošč, smo izdelali asimetrične plošče. V osnovi smo izdelali trislojne iverne plošče in sicer je bilo razmerje med zunanjima in srednjim slojem 50/50, pri čemer smo spreminjali delež iveri zunanjega sloja. Pri referenčni plošči je bilo razmerje med spodnjim in zgornjim zunanjim slojem 50/50, pri plošči B je bilo razmerje 30/70, pri plošči C pa 10/90. Ploščam smo določili gostoto, gostotni profil, upogibno trdnost, natezno trdnost, razslojno trdnost in nevtralno os. Ugotovili smo, da se s spreminjanjem zgradbe plošče, predvsem količine gradnikov v posameznem zunanjem sloju, spreminja upogibna trdnost in mesto lokacije nevtralne. Particleboards play an important role in the wood industry, since they give added value to recycled and low value wood. Particleboard is made from fine particles in the surface layer and medium size particles in the core layer. Even though they are supposed to be symmetrical, in practice this is mostly not the case. This has been seen in comparisons of the bending strength of the upper and lower sides of panels and through the neutral axis position. In the presented research we investigated the impact of changes in the surface layers on some mechanical properties, as well as on the location of the neutral axis. We made asymmetrical boards from spruce wood with a surface to core layer ratio of 50/50. The difference between panels is in the distribution of the surface layer. In board A the upper and lower parts of the surface layer had an equal mass of particles (50/50), while in panel B the surface layer ratio between the upper and lower sides was 30/70 and in panel C 10/90. We determined the density, density profile, bending strength, modulus of elasticity and internal bonding strength. We also determined the location of the neutral axis with regard to panel structure. The tests were comparable and showed that with different ratios the neutral axis moves from the middle of the board to the lower outer layer. The results of the tests make it possible to determine how a board is made, and how best to use, embed or even make it again. iverna plošča nevtralna os razmerje zunanji notranji sloj mehanske obremenitve particle board neutral axis ratio outer inner layer mechanical loading true false false [G. M. Černe] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2024-06-23 07:16:15 2024-06-23 07:16:20 2024-07-06 03:48:39 0000-00-00 00:00:00 2024 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 630*862.2 236835 200200451 MAG_Cerne_Gregor_Matija_2024.pdf MAG_Cerne_Gregor_Matija_2024.pdf 1 1CF37DDA118DA3BA8CD0F82EBA394C6A 919551a605a724b4da910bd4aab68bf8c5e8c17a89c176297d213b6754d4dc30 b9e3b010-311f-11ef-8779-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=186668 Biotehniška fakulteta 0 0 0