METHOD OF DETERMINATION OF THE INITIAL MODULUS OF ELASTICITY AND THE MODULE OF WOOD DEFORMATIONS OF DIFFERENT AGES

Abstract

Methods for determining the initial modulus of elasticity and modulus of deformation according to current standards are analyzed in detail. The method of determining the initial modulus of elasticity and the modulus of deformations of hardwood and coniferous species of different ages is given. Based on experimental studies, it is established that the dependence of "stress σc - strain uc" on a single short-term compression along the fibers with a constant rate of deformation due to the manifestation of plastic deformations occurring at the lowest stresses is nonlinear from the beginning of loading. But with increasing stress, the curvature of the diagram with longitudinal compression of the wood also increases. A formula for determining such values ​​is proposed. Experimental and statistical studies with high reliability have shown the presence of linear correlations between the January modulus of strain and the stress level. The linearity of the dependences is confirmed by the high degree of correspondence of the correlation and experimental values ​​of the deformations: the absolute value of the correlation coefficient r is close to unity, its reliability r / mr is always more than four. When constructing the dependence, the experimental points in the voltage range η = (0.2 ... 0.8) were taken in accordance with the recommendations. Diagrams (January module - stress level) for solid wood aged 20 to 60 years with short-term compression along the fibers are constructed. It is established that as the stress level η increases, the cross-sectional value of the modulus of modified wood gradually decreases. It is established that with the increase of wood age from 20 to 60 years the initial modulus of elasticity and the modulus of deformations increase. In the future it is necessary to test solid wood of different ages under the influence of an aggressive environment.