Том 45, № 5 (2016)

This paper is concerned with the kinematics of the deployment of petal-type large space antenna reflectors with axisymmetric petal packaging. The classification and technical design solutions for petal deployment mechanisms and the results of their comparative analysis have been presented.

A manipulator with three degrees of freedom similar to a Delta robot has been considered. The mechanism degree of mobility has been analyzed and, in the general case, the mechanism has negative mobility. Structural diagram of the mechanism with three degrees of freedom similar to the original one is constructed for solving the direct and inverse kinematic problems. A method for determining mobility based on the study of coupling equations of the mechanism has been proposed. The method is applied to the considered spatial mechanism, an analogue of a Delta robot. The direct kinematic problem has been solved.

With regard to the problem of decreasing the vibration activity of devices that perform the translational motion of the working body along the pathway, new results have been obtained that determine the threshold speed value; the friction self-oscillations occur lower than this value. It has been established that this value increases upon a decrease in the dissipative characteristics of a drive. The dual character of the influence of the high-frequency disturbance, which leads to the positive effect due to the vibration linearization of the dry friction forces, but simultaneously decreases the realized dissipation level of a drive, has been studied. The optimization of the high-frequency excitation parameters has been performed based on an analysis of the combined influence of these factors. The main conclusions have been proved based on the results of computer modeling.

The paper presents the results of an experimental study on the features of fatigue crack development in 20GFL grade low-alloy steel of a freight car bolster with simulation of the operating process of loading. The experiment results are compared with calculations using the fatigue failure diagram for this steel.

The article provides a solution to the problem of determining the probability of the nondestruction of the beam site of an oil and gas pipeline with axial compressive force when the pressure, diameter, wall thickness, span length, the coefficient of linear expansion, temperature difference, Poisson’s ratio, and ultimate strength are distributed normally. According to these data, parameters are established under which the emergency failures of oil and gas pipelines are reduced and their specification level of reliability is provided.

The algorithm for calculating a fatigue crack formed in force parts of structures under the harmonic vibration load has been presented. The source data for calculating an unknown quantity are fatigue curves in the material and the assumed linearity of the first section of the kinetic diagram of the fatigue fracture. All of the necessary parameters for describing the law of crack propagation in the form proposed by Paris are determined by the characteristics of the fatigue curve. This approach shows that the fracture of the thin-walled force parts of structures with a thickness of less than 2 mm (the size of a fatigue crack for which the fracture of samples is tested to develop the fatigue curve) occurs at a smaller number of cycles than that shown in the fatigue curve for the same stress amplitude.

The possibility of well stimulation via wave impact has been studied. The effect of an increase in the filtration capacity of the bottomhole zone in a reservoir observed during treatment with high-frequency waves has been surveyed.

A problem for designing aviation structures made of sandwich-like polymer composite materials has been examined based on the example of a typical device for mechanizing a wing-spoiler. The spoiler’s loading pattern is chosen according to topological optimization. A way to determine the orientation, number, and proper order of layers laying has been examined as a problem of discrete optimization by using different algorithms. The peculiarities of layered structure simulation have been discussed. Tests results for spoiler have been presented and they verify the design and technological solutions.