Sokolovskyy Ya., Kryshtapovych V., Mokrytska O. Determination of rheological properties of wood depending on changes of temperature and humidity.

Abstract

An research of the viscoelastic behavior of wood taking into account the structural anisotropy depending on changes in temperature and humidity. Substantiated analogy of the method for predicting creep along the wood fibers, allow-ing the results to predict short-term studies on the rheological properties long time. To substantiate the size of the cross-section of the working models take into account the availability of the required number of anatomical elements characteristic of wood. An research of the methodology and the parameters of the time factors analogies. Substantiated rheological behav-ior of wood across the fibers in tangential and radial directions depending on changes in temperature and humidity. Estab-lished function creep and relaxation time dependences wood from changing temperature and humidity conditions. Deter-mined linear relationship between immediate and long elastic modulus wood, pine and spruce plain in the direction of defor-mation. For the approximation of the experimental curves of creep method uses the interpolation function as a sum of expo-nentials. Built necessary for the further calculation of the stress-strain state of wood kernels of creep and relaxation with the consideration of accumulation of residual deformations and the developed algorithms determine the characteristics of the functions of rheological conduct of wood on the basis of approximation of experimental data creep. To establish the analyti-cal form of the kernel of creep required to calculate the strain-relaxation properties of wood used experimental data of creep deformation of the material for different temperature and humidity conditions. So, the choice is conditioned creep kernel fea-tures rheological behavior of wood. Approximation calculation results for the relaxation time creep wood pine and spruce es-tablished regression equation. Based on the comparison of statistical estimates of reproducibility and accuracy of the ap-proximation of results of studies on creep of birch wood along the grain the possibility of predicting the viscoelastic proper-ties of wood based on the governing parameters of rheological behavior of wood depending on moisture content and tempera-ture of the material. Key words: creep, relaxation, viscoelastic deformation, woood.