Influence of finishing materials on viscous elastic properties of wooden structures = Utjecaj premaznih materijala na viskoelastična svojstva drvenih elemenata / Darius Albrektas, Elvyra Revuckaitė, Vaida Dobilaitė, Milda Jucienė.
Sažetak

In this study, the effect of finishing process on the mechanical properties of oak and pine wood elements were investigated. A special test stand was used for this purpose. Specimens were divided into subgroups, the resonance frequency of the specimens was determined (when they vibrate in mode of a theoretic isotope beam), and the modulus of elasticity (MOE) and damping coefficient were estimated. It was determined that MOE of oak and pine specimens was 8415-10570 MPa and 8220-14104 MPa, respectively, while damping coefficients were 0.014-0.019 r. u. and 0.013-0.026. Afterwards, some specimens were varnished (pentaftal varnish was used), while the specimens from others subgroups were oiled (water-based outdoor wood oil was used) and after each processing step, the viscous elastic properties of the specimen were recorded. The specimens were finished four times – first, one side was finished in two layers, and then the other side. For the determination of elastic properties of the finishing materials, films were prepared separately. The fi lm formation was carried out by casting liquid on a smooth, siliconised surface of a test panel. The tensile test was carried out using the universal testing machine. It was established that MOE of films varied in the range of 4-7 MPa. After the varnishing process, the MOE of oak and pine elements decreased by 5 % and 7 %, respectively, while the damping coefficient decreased (in varnish case) by 60 %. The impact of oil on viscous elastic properties of the specimens was quite marginal.; U radu je istraživan utjecaj procesa površinske obrade na mehanička svojstva hrastovine i borovine. Za istraživanje je pripremljeno posebno postolje. Uzorci su podijeljeni u dvije podskupine, utvrđena je njihova rezonantna frekvencija (kada vibriraju u modu teorijskog snopa izotopa) te su procijenjeni modul elastičnosti (MOE) i koeficijent prigušenja uzoraka. Utvrđeno je da je MOE uzoraka od hrastovine 8415 – 10 570 MPa, uzoraka od borovine 8220 – 14 104 MPa, a koeficijent prigušenja iznosio je 0,014 – 0,019 r. u., odnosno 0,013 – 0,026. Nakon toga dio uzoraka je lakiran (upotrijebljen je pentaftalni lak), a uzorci iz druge podskupine premazani su uljem (uljem na bazi vode za vanjsku primjenu). Nakon svakog procesa obrade uočena su viskoelastična svojstva uzoraka. Uzorci su premazani ukupno četiri puta – najprije je u dva sloja premazana jedna, a zatim druga strana uzoraka. Za određivanje elastičnih svojstava premaznih materijala posebno su pripremljeni filmovi, i to nalijevanjem premaznog materijala na glatku, silikoniziranu površinu ispitne ploče. Vlačno ispitivanje obavljeno je na univerzalnom uređaju za mehanička ispitivanja. Utvrđeno je da MOE filmova varira u rasponu od 4 do 7 MPa. Nakon lakiranja MOE hrastovih elemenata smanjio se za 5 %, borovih elemenata za 7 %, a koeficijent prigušenja na lakiranim uzorcima smanjio se za 60 %. Ulja su neznatno utjecala na viskoelastična svojstva uzoraka.