DYNAMICS OF CHANGE CRITICAL DEFORMATIONS OF WOOD WITH DIFFERENT HUMIDITY INDICATOR

Abstract

The analysis of literature publications on determination of relative critical deformations of continuous wood on compression along fibers at short-term loading is carried out. It is established that in the literature, in fact, there are no methods for studying such parameters with different humidity, except for some works Grinkrug NV It was found that the critical relative deformations can be determined experimentally only when testing samples under a rigid test mode. Such studies were conducted at different humidity on modern test equipment and established the true values ​​of critical relative deformations of deciduous (birch, alder, ash) and coniferous (larch, pine, spruce) wood species. The method of determination of relative critical deformations of solid wood of deciduous and coniferous breeds at different indicators of humidity by axial compression along fibers is given. A formula for determining the relative critical deformations of solid wood at different humidity, which includes elastic and plastic components, is proposed. This formula is not empirical in nature and depends on the humidity and age of solid wood. The proposed formula was found to be in good agreement with the experimental values. The dynamics of change of critical relative deformations at different humidity of all studied wood species, as well as its components - elastic and plastic - are given. It is established that drying of wood from 30 to 12% reduces its deformability. It was found that the plastic component of relative critical deformations decreases with wood drying from 30 to 12%, and the elastic component increases on the contrary. In the future it is necessary to determine the relative critical deformations of glued and modified wood of different deciduous and coniferous species experimentally and theoretically, as well as to determine the elastic and plastic components.