Pobereyko B. The theoretical basis for computation of the wood strength with variable mass transfer of heat potentials

Research object - the strength and deformability of anisotropic hygroscopic materials and wood. Aim of the study - development of theoretical bases of calculation of strength of wood with varying potentials mass transfer of heat that takes into account and adequately reflects the patterns of strength change depending on changes of material stress and temperature -humidity conditions. Research methods - methods of continuum mechanics, thermodynamics of irreversible processes and theory of heat mass transfer, numerical methods for determining roots of nonlinear equations with two unknowns.The novelty of study - the basic theoretical principles were further developed for wood drying on the relationship and interconditionality of deformable, relaxation and processes and processes of heat mass transfer in hygroscopic materials, new equation of wet-heath transfer derived what allows you to discover new patterns of stress fields influence on the processes of heat transfer and moisture in drying wood. It was developed the theory of strength of anisotropic capillary-porous materials with a strong asymmetry of the limits of durability, strength criterion is constructed in contrast to the presently known criteria what helps to identify the limiting stress state of wood with changeable unevenly distributed moisture and temperature fields. Practical significance have: a new method of direct measurement of residual stresses in the layers of dried lumber and algorithms and software for calculating the limiting stressed state of the wood, which allows to group the stacks of dried boards by grade; it is proposed a new method of measuring the current stresses on the surface of the timber which is in the process of drying, strength criteria developed that allow to detect and monitor the development of dangerous for form changing stress fields in boards of drying stack. Main principles and research results used to improve existing methods for detection of dried timber quality and efficiency of the drying process. Sector for implementation - woodworking industry.