Том 47, № 1 (2018)

Rotor system oscillations are considered for the rotation of the rotor inside lightweight moving elements (for example, inside floating seal rings, and hydrostatic bearings). In this case, the ring runs around the rotor in a direct precession mode (hula-hoop type of oscillations). The oscillations of the rotor-floating ring system are studied taking into account hydrodynamic forces in the gap and contact forces of dry friction. A solution is obtained in analytical form. It is shown that the ring precession speed under the running-around is close to its own frequency at a given rotation speed. Trajectories are plotted for the motion of the ring.

The paper is devoted to a numerical simulation and optimization of wave-mixing processes in oscillatory-type plants. We consider different variants of the spatial arrangement of working elements (blades). The computational experiment consists of three stages: simulation of the fluid flow, inside which there is an oscillating body; simulation of the evolution of the admixture amount in the carrier medium; and calculation of the criteria for mixing efficiency. Based on the results of numerical analysis, we propose an approach to the optimal arrangement of working elements in space, which provides the basis for automation of the design process for wave-mixing devices.

A generalized mathematical model describing self-oscillating volume-type hydroimpact systems of bidirectional and monodirectional direct and back action is presented. Dimensionless variables are introduced, and the main dynamic similarity criteria having a similar physical meaning for these classes of systems are determined. The peculiarities of changes in the output characteristics of the systems (preimpact velocity of the striker, cycle time, and system efficiency) are explained in the space of the basic similarity criteria and are compared. An example of the application of research results to the selection of basic parameters of hydroimpact systems is given, and it can thus be used at a stage of preliminary design.

As a result of theoretical and experimental surveys, it is established that the value of the limiting gradient of industrial railways affects the temperature change in the contact area of the wheel–rail system of the locomotives and is characterized by the temperature coefficient of the gradient (k_gradient).

The results of the authors’ development and research of an energy-saving converter ensuring a sufficiently high level of energy-saving are presented. The problems of the functional construction and engineering implementation of an energy-saving electric power converter from the mains based on a pulse charge of reactive storage devices upon converter input with controlled amplitude of their voltage and the periodic conversion of it to the AC supply voltage of resistive load were considered. The characteristics and operation features of the proposed energy-saving converter are analyzed.

The mathematical model of an all-wheel drive (AWD) vehicle and the procedure of evaluating power losses on spinning are suggested, allowing us to select the optimal type of interaxle drive.

An analysis of the possible use of the known generalized Willenborg model for modeling of the process fatigue crack propagation in 20GFL steel under harmonic loading with tensile overload cycles was carried out. The overload values were selected as characteristic for the operating railway spectra.

This article presents a phenomenological model of brittle fatigue failure of metals and alloys upon proportional (simple) loading. The model is developed in the frames of physicomechanical approach as a set of hypotheses on the gradual development of defects in metals at various scale and structural levels (such as brittle micro- and macrocracks). On its basis, defining relationships are formulated for probability of failure with regard to defects of each level. Fatigue curves are obtained for various ultimate metal states as a consequence of the evolution of micro- and mesodefects, and the lifetime is determined with regard to a predefined level of accumulated defects. The results for structural steels are given as an example.

The paper presents the results of comprehensive research of the influence of wave technologies on the physical and mechanical properties of fine-particle clay suspensions. The research was conducted under laboratory conditions at NTs NVMT IMASh of the Russian Academy of Sciences and field conditions. It is shown that the wave treatment of the drilling mud by flow-type hydrodynamic vortex generators with tangential and radial ducts and flat generators with cylindrical bluff bodies considerably enhances the quality of the drilling mud, increases the colloidal fraction, reduces the consumption of clay powder, and decreases the time of preparation of the drilling mud by several times compared with the conventional technology. It is shown that the nonlinear wave and cavitation processes that occur in the flow path of hydrodynamic generators make the major contribution to achieving high efficiency of the wave treatment.

A solution of the problem of optimization of the technological process of turning KhVGhardened steel (HRC 55) is presented. The radial component of cutting forces during the machining of hardened steel by cutting ceramics is accepted as the optimization parameter. The influence of two factors, the cutting rate and feed per revolution, were examined. An orthogonal central composition plan was used to solve this problem. The empirical dependence of the radial component of the cutting force on the cutting rate and feed per revolution is presented. The character of the influence of each factor on the parameter optimization is determined. The optimal values of factors corresponding to the minimum value of the radial component of the cutting force were finally determined.