INFLUENCE OF AGGRESSIVE ENVIRONMENT ON STRENGTH AND DEFORMABLE INDICATORS OF CONTINUOUS TIMBER OF CONIFEROUS BREEDS

Abstract

Timber is used in many industries and is exposed to various aggressive environments, both protected and unprotected. Suchmaterials work in aqueous, alkaline, and acidic environments. Due to the aggressive action of the physical and mechanical properties of wood undergo certain changes, usually deteriorating. A detailed analysis of the literature of domestic and foreign scientists to study the impact of aggressive environments on the strength and deformability of solid timber of deciduous and coniferous species. The technique is developed and experimental researches of continuous timber of coniferous breeds on compression along fibers at shorttermloading with various indicators of humidity at a rigid mode of tests are carried out. The volume of experimental researches is given.The total number of tested samples of solid timber of all studied species is 54 pcs. For the first time, the main parameters of  strength and deformability at different humidity indicators, both on the ascending and descending branches, of the complete deformation diagram of coniferous timber were determined. The dependences of such parameters as ultimate strength, initial modulus of elasticity, and critical deformations on different humidity are established. After analyzing the test results, we conclude that the reduction of timber moisture from 30% to 12% contributes to a significant increase in its strength for softwoods – 2.1–2.4 times. At the same time deformability of deciduous and coniferous breeds decreases. The decrease in deformability can be explained by the fact that timber with higher humidity is a more malleable material compared to timber with lower humidity. It is established that the plastic component of relative critical deformations decreases at drying of wood from 30 to 12%, and elastic – on the contrary increases.