Influence of Finishing Materials on Viscous Elastic Properties of Wooden Structures

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.