Том 48, № 3 (2019)

The results of computer modeling of mixing in a system of mobile coaxial cylinders are presented. Detailed spatial-temporal descriptions of the processes are obtained, and the principal structures in the flow field are determined. On the basis of the analysis of the singular points of the fluid vector field, a way of rotor profiling is proposed. The similarity numbers are introduced, which allow us to proceed from laboratory stand installations to real industrial devices.

This work is dedicated to consideration of generalized mathematical models of parallel structure of the Delta type. The main design dependences for kinematic chains with four or six degrees of freedom are presented. An example of calculation of the working space, as well as the solutions of inverse problem on speeds (using theory of screws) for the mechanism with four degrees of freedom, are presented.

In this paper, we considered the bending of a round shallow panel under the effect of excessive pressures on the lower and upper surfaces. A refined expression of the distributed transverse force that depends on both the pressure drop on the surface and the interaction of the average overpressure and curvature of the middle surface is used. This refinement is performed in a linear approximation. The panel edge is assumed to be isolated from excessive pressure. The classical theory of nonlinear bending of a round shallow panel under the effect of pressures on its surface is supplemented.

Formulas for calculating the required number of test objects and the duration of lifetime tests are proved depending on the estimate of the reduced mean lifetime lower confidence limit for a given confidence probability. The calculation formulas are valid for any time-to-failure law for a technical object. Examples of application of the lifetime test results are given.

To make structural components and vehicle parts reliable, it is necessary to study accumulated structural damage and its influence on the properties of materials, taking into account the operational environment. To discover the relation between structural changes in and brittle fracture strength of materials, we studied the degree and kind of structural damages, impact toughness, and microscale processes of destruction observed in the metal of springs mounted on Kamaz trucks driven in a northern environment. The techniques used in this article include optic and electron microscopy and structural statistical analysis of the microhardness and porosity according to which the structural damage was evaluated. New data are derived about accumulated fatigue damages and their influence on the brittle fracture resistance of the metal in springs used in a cold climate environment. The results can be used to extend the service life of elastic parts of automotive vehicles.

A magnetic-tape locomotion mechanism of a wall-climbing robot is developed. A mathematical model of the motion of a mobile robot on vertical surfaces is proposed. The basic hierarchical elements of the mathematical model are considered. A method for automated formation of a set of differential equations for complex mechanical systems is developed. The motion stability of the mobile robot and the dependence of the capacity of drive motors on the locomotion speed are investigated.

Results and hypotheses are presented concerning the reasons for decreasing fuel consumption by automotive-and-traction internal combustion engines in the case of fuel activation using a combined static mixing activator (RF patent no. 2411074) designed for the economically efficient operation of motor transport, and for the production of various grades of motor fuel.