Storozhuk O. Determination of the non-isotropic elastic features for wood by an ultrasonic method.

Object of the study - deformation of wood in technological processes. Purpose - theoretical and experimental determination of anisotropic elastic properties of wood by acoustic method and improved methods of their controlling by speed of acoustic waves spreading. Methods - Methods of continuum mechanics, acoustic NDT methods, methods of planning experiments theory, methods of mathematical statistics. Scientific novelty - mathematical model of acoustic wave spreading in such anisotropic elastic materials as wood futher developed, that establishes a relationship between the mechanical properties of wood and spreading of acoustic waves with the changing temperature and humidity of material, for the first time a mathematical model of acoustic waves spreading in a wood proposed, which takes into account exponential type functions with rheological behavior of wood and allows determination of viscoelastic properties, methods of determining a speed of acoustic waves spreading in a wood developed, which reduced measurement error significantly. Practical significance: The results allow to predict the mechanical properties of wood for the acoustic waves spreading with the changing temperature and humidity of the material, a new method of acoustic qualimetry, grading the strength of softwood and hardwood timber with rectangular profile for constructional purposes developed, acoustic methods simplify and speed determination of wood mechanical properties, device which was designed and developed provides contactless determination of the speed of acoustic waves spreading in a wood; algorithms for processing acoustic signals developed as well. Research results: an important and urgent scientific problem have been solved which is aimed to establish relationships between mechanical properties of wood as an anisotropic elastic material and the velocity of acoustic waves on the basis of variable temperature and humidity conditions which is essential for wood processing technology. Field of study - wood processing.