IMPROVEMENT OF MECHANICAL PROPERTIES OF WOOD AT THE ACCOUNT OF THEIR ADHESIVE

Abstract

High-quality solid wood of deciduous and coniferous species in Ukraine is becoming less and less every year. Therefore it is necessary to use that wood which is available. Various methods and techniques are used to improve the mechanical properties of wood. One of them is gluing wood boards of different thickness. In this article we present the following studies taking into account the actual work of the material.
 The method of researches of glued wood of different breeds by axial compression along fibers by short-term loading at standard humidity (by increase of displacements) is given. Complete deformation diagrams “stress σc - deformations uc” are constructed and the main parameters are established: maximum disturbances, critical deformations, initial modulus of elasticity. The strength of glued wood increases in comparison with the indicators of continuous humidity of 12% at the age of 60 by 13-25%; critical deformations slightly increase or decrease in one direction or another; the initial modulus of elasticity increases by 13–31%.
 This improvement is due to the ingress of glue into the body of wood, ie due to gluing is the modification of wood and the formation of composite material. The strength of such a composition is directly affected by the thickness of the board. The smaller the thickness of the board, the stronger the product.
 It is established that the deformation diagrams of glued wood have two branches: ascending and descending. That is, the work of such composite materials is observed, both in the subcritical stage and in the supercritical stage. Therefore, the samples have a certain residual strength after passing the maximum stress values.
 It has been established that gluing wood increases the strength and initial modulus of elasticity of the composite material and depends on the thickness of the board.