ИССЛЕДОВАНИЕ ДИНАМИЧЕСКИХ СВОЙСТВ ДРЕВЕСИНЫ ПРИ ОДНООСНОМ СЖАТИИ

Abstract

The paper presents the results of an experimental study of dynamic deformation and fracture of pine samples under compression under uniaxial stress conditions. The experiments were carried out using the classical version of the Kolsky method. Dynamic tests of pine samples cut in three directions relative to the fibers were carried out: along and across and at an angle of 45 degrees. At least three modes of loading intensity (strain rate) are implemented for each orientation of the sample. Within each mode, at least five repeated tests were carried out with the averaging of the data obtained and the determination of the scatter characteristics. As a result of the experimental study for each tested sample, time dependences of strain, stress, strain rate of the samples were obtained, deformation diagrams were constructed. The analysis of the data obtained made it possible to determine the strain rate dependences of the ultimate strains, ultimate stresses, as well as the time of the beginning of fracture (lifetime). For each direction of sample cutting, the dependences of the dynamic increase factor on the strain rate are obtained. It is shown that the strain rate significantly affects the strength and deformation characteristics of pine. A tendency to increase the ultimate values of strains and stresses with an increase in the strain rate is obtained. At the same time, the time of the beginning of fracture decreases. The influence of the loading direction of the sample relative to the orientation of the fiber was also significant. The most durable is the direction along the fiber. The dynamic increase factor for the studied directions on the right limit of the realized strain rate range was about 3. The data presented in the work can be used in the tasks of assessing the dynamic strength of structural elements made of pine.