Journal of Machinery Manufacture and Reliability最新文献

In this article a technique is described and the optical microstructure of the multiphase alloy BrAZh-9-4 is analyzed based on structurally ground copper. Features of the microstructure of this alloy are studied by assessing the spatial homogeneity of materials based on the geometric characteristics of phases and the structural components. To analyze the structural characteristics of the material, the following quantitative image characteristics were used: statistical separation of phases using clustering, phase identification based on the level of coloration of gray image pixels, determination of histograms of grain size distributions, and the total areas (lengths) of grain boundaries and phases. Based on the results of this study, a conclusion was made about the degree of refinement of the α and β phases, the enlargement of the γ phase due to the decomposition of the α and β phases during cooling of the alloy after ECAP treatment, the increase in the length of the grain boundaries of the material, and the uniformity of the distribution of phase grains over the microsection area.

The problems of manual control of a manipulator using motion controllers with a logical output signal are considered. Controllers of various designs and logic of action are considered. Various control modes and principles are highlighted that allow the simultaneous operation of several drives using the example of a mechanism with four degrees of freedom and a remote center of rotation. Recommendations are given for choosing control methods and laws when developing spatial manipulators.

The velocity profiles and volumetric concentrations were measured using a laser doppler anemometer for a vertically ascending two-phase liquid–liquid droplet flow in a cylindrical tube, where the density difference between the phases is relatively small. This regime simulates the flow of a two-phase gas–liquid mixture in microgravity. The small phase slip velocity was experimentally measured. New methods have been developed for using a laser doppler anemometer to measure the velocity and volumetric concentration of phases in a dispersed two-phase flow.

This article studies the effect of single-layer electrolytic coatings made of nanosized copper powders obtained by chemical deposition on the sound level, i.e., on the sound pressure level of high-strength cast iron. However, the damping capacity of high-strength cast iron is lower and its strength is high. This makes it possible to produce new coating materials using new technologies and new methods to improve the properties of high-strength cast iron. In order to improve the damping capacity by applying a galvanic coating to the surface of high-strength cast iron, it was possible to bring its damping abilities somewhat closer to the abilities of gray cast iron.

High-entropy coatings based on 3D metals have a unique combination of strength and ductility over a wide temperature range and can be obtained using vacuum ion-plasma magnetron sputtering technology. However, the model calculations of the thermomechanical properties of such alloys are complicated by a lack of stable and equilibrium lattices with complete structural information. This article implements prediction of the stability of the phases of an equiatomic high-entropy coating of CrMnFeCoNi by the inverse convex hull method. The thermodynamic and mechanical properties were determined. It was found that, up to room temperature, the medium-entropy, 4-element alloy of composition MnFeCoNi also belongs to the stable phases.

Vibrations in mechanical systems with geometric symmetry have been studied. It has been shown that, in systems with a low level of asymmetry, stratification of multiple natural frequencies occurs, which leads to instability of forced vibrations in this frequency range, as well as to beats occurring in the course of natural vibrations. In the case of mechanical systems, symmetrically arranged structural elements usually have several degrees of freedom or represent separate subsystems. Therefore, block symmetry operators and basis vectors that characterize the interactions between these structural elements determined by the symmetry conditions have been introduced. It has been shown that, for systems with a symmetry hierarchy, the resulting symmetry operator represents the product of the operators corresponding to each symmetry group. It has been found that the basis vectors for a given type of symmetry remain the same for nonlinear systems with the same type of symmetry. Their use makes it possible to divide the initial equations with an odd nonlinearity function into independent nonlinear equations, each of which describes its own coordinate. The mathematical apparatus of the theory of group representation is used.

This article assesses the technical condition of the air supply system of the Ford Transit commercial vehicle. After the analysis, results were obtained that allow identifying the reasons for the failure of the intake system of the diesel engine with the Euro5 emission standards. It was found that the malfunction of the turbocharger directly affects the overall condition of the engine and its performance characteristics. The main failures are associated with the malfunction of the turbocharger itself and the leakiness of the pipes or intercooler. The probabilities of occurrence of these failures are determined for the Duratorq TDCi 2.2 engine.

The results of an experimental analysis of the influence of an elastic vibration limiter on the dynamics of a vibration machine with self-synchronizing vibration exciters when interacting with granular material in the resonant frequency range are presented. The experimental model is made according to the scheme of a single-mass vibration machine with working body (platform) plane oscillations, which are excited by two unbalanced vibration exciters. The dependences of the vibration amplitudes of the model and the mutual phase of rotation of the vibration exciters on the excitation frequency were obtained for various values of the mass of the material. It has been found that contact with the elastic limiter leads to expansion of the frequency region near the second resonant frequency, in which synchronous rotation of vibration exciters with a mutual phase close to zero is ensured, as well as to a decrease in the resonant frequency regions of the sensitivity of the vibration amplitudes of the platform to changes in the mass of the material. The effectiveness of introducing an elastic limiter when processing granular materials has been shown.

AlMgB₁₄ and AlMgB₁₄–50 wt % TiB₂ coatings deposited onto a VK-8 hard-alloy substrate by ion-plasma sputtering using powder ceramic targets are studied. It is established that the formed coatings are characterized by an amorphous-crystalline structure containing B–B, B–O, and Ti–O interatomic bonds. The composition of the target has a minor effect on the morphology and roughness of the obtained coatings. The hardness of TiB₂-free coatings reaches 35 ± 2 GPa at the lowest friction coefficient of 0.12. It is established that the coatings formed using the AlMgB₁₄–50 wt % TiB₂ target possess higher adhesion strength and wear resistance.

Based on the synthesis and improvement of existing methods, a forecasting model is proposed, which includes an algorithm for checking the performance of a product based on the results of monitoring its units. Models have been developed for predicting the monitoring parameters of complex technical systems and methods for optimizing the number of tests of units of technical systems when monitoring their performance. The effectiveness of the proposed performance prediction algorithm is demonstrated using an example. The materials and results of this article can be used by engineering workers at design bureaus, research institutes, and research and production associations in the process of designing highly reliable systems.