Objective. In this study, the task is to establish the theoretical prerequisites for the operability of a regressive-progressive elastic mechanism by comparing the amplitude-frequency characteristics and phase trajectories with a linear elastic system of comparable stiffness in a static equilibrium position.Methods. The article presents a comparative dynamic analysis of vibrations of elastic systems with linear rigidity and regressive-progressive characteristics obtained as a result of the use of elastic elements in the form of high flexibility rods with longitudinal eccentric compression. Such elastic elements in various design variants have been tested and patented as damping elements for use in the construction of vibration dampers for construction structures and vehicle suspensions, and have experimentally shown their effectiveness in damping vibrations.Results. The regressiveprogressive elastic characteristic obtained by the elliptic parameters method and using the ANSIS calculation complex is used in the dynamics equations in an approximated form, which expands the capabilities of the method. It is shown that increasing the energy intensity of a curvilinear system reduces the vibration amplitude.Conclusion. The regressive-progressive change of the stiffness of curvilinear elastic systems can be achieved using an elastic element with eccentric longitudinal compression; the regression plot of elastic properties is achieved due to eccentric compression; the progressive plot – through the use of a guide or other design solutions. The implementation of this characteristic allows using such elastic mechanisms in systems where the accumulation of potential energy occurs with a smaller compression stroke for the same perturbation than for linear systems.

Objective. The aim of the study is to determine the dependence of the normal stress on the radius of curvature of a flexible rod at different thicknesses. Method. A method was applied to determine the maximum stresses in a longitudinally compressed rod of high flexibility using elliptic integrals.Result. Modeling of a thin-walled longitudinally compressed rod was performed in the ANSIS calculation complex.Conclusion. The exact theory for calculating flexible rods allows you to determine the value of the axial force during longitudinal compression, at which the ends of the rod will close. When solving the problems of practical use of this type of rods, it is of interest to determine the maximum stresses, and at any stage of deformation, which makes it possible to choose the dimensional parameters of the elastic element and its material with greater accuracy.

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Abstract. Aim. The possibility of obtaining the regressive part of the elastic (regressiveprogressive) characteristic under axial loading in the initial period is studied by applying an elastic rod having an initial curvature under vertical compressive load. The objective of the study is to determine the static characteristics of such a rod without taking the resistance forces into account. Method. To solve the problem, the elliptic parameters method was used to make a comparison with a solution obtained using the finite element method in the ANSYS engineering simulation software. Results. A technique was developed for assessing the strain state and displacements of a flexible rod with initial curvature in order to study the regression-progressive characteristic of various elastic systems having initial curvature for their effective use in determining oscillations. Conclusion. The obtained technique can be used to determine the deformed state of an elastic flexible rod having initial curvature and displacement of the point of application of force. At the same time, by setting various initial parameters of the flexible rod in order to obtain a regressive-progressive characteristic, significant displacements can be obtained in the subcritical region when the axial load does not exceed the Euler force for this flexible rod

A technique for selecting an electrode material used when applying the electrospark method onto a metal surface layer is described. The technique is based on the study of the mechanical properties of the coating by nanoindentation. The coverage microhardness distribution in depth for a number of the investigated materials is developed. As a second characteristic of the material, the plasticity index reflecting the structural state of the material is used during the indentation. Value H/E is also used to describe the capability of materials to frictional wear. A qualitative comparative characteristic — ratio H3/E2 was used to assess the resistance of materials to plastic deformation. Based on the analysis of the obtained results, a reasonable choice of the electrode material which creates coatings with sufficiently high mechanical properties is made. The relevance of the study is proved by the advantages of the electrospark alloying (ESA) which is an effective method of impact on the surface layers of the various parts.