ИСТИНА

One of the important tasks in the field of solid mechanics is to study the effect of different types of stress concentrators on the behavior of structural elements. The aim of the work is an experimental study of the stress-strain states in hubs using the method of digital image correlation. In this work we consider the use of three-dimensional digital optical system, Vic-3D, the mathematical apparatus of which is based on the method of digital image correlation. The video system is designed for the analysis of displacement fields and strain on the sample surface. This article describes the technique of the experiment with the use of a digital optical system, its structure and working principle. The mathematical foundations of the computing device system were formulated, and uniaxial compression „Brazilian test“ were done in order to develop the methodology of the experiment using a digital optical system. The results of the uniaxial tensile tests on plates made of plexiglass with concentrators of different geometries, as well as the results of tests on a uniaxial tensile carbon plate with a circular hole using a digital optical system, were presented. Mechanical uniaxial tensile test were performed on the test system Instron 5882 and Instron 5989, together with the use of digital optical system Vic-3D. As a result of the plates tensile test, transverse, longitudinal, shear deformations, as well as the intensity deformation fields were constructed. The use of video system made it possible to detect not only changes in strain, but also to assess the impact of stress concentrators that implement complex stressstrain state of the material. The system allowed to record the evolution of the fields of displacements and strains to evaluate the nature of heterogeneity of fields to keep track of the material deformation processes occurring on the surface of the sample. The add-on software video „virtual extensometer“ was used in determining the mechanical properties of the material. The high efficiency of the method of correlation of digital images in the study the behavior of the material in the event of non-uniform strain fields was shown.