Journal of Machinery Manufacture and Reliability最新文献

Materials on the symmetrical influence of thermal fields on the side opposite to a hard-surfaced side, expressed in the same form of hardness distribution diagrams, are presented. The introduction of conditional criteria for assessing the properties of the thermally affected zone makes it possible to assess its stress state indirectly. The numerical values of the hardness of individual sections of the hardened sample are obtained.

The features of technical solutions for additive manufacturing of parts are discussed. In contrast to existing solutions for layer-by-layer synthesis, a new method and device is proposed for the movement of a working tool in the volume of a powder. Various implementation options are considered using morphological analysis by constructing a morphological table. This ensures the validity of the proposed technical and technological solutions and, therefore, will improve the technical level and efficiency of the synthesized systems. An analysis has been made of solutions that provide less expensive production of three-dimensional objects due to better process control, which leads to higher productivity and reduced cost of both the technological process and the equipment. It also becomes possible to create more compact, lighter, and cheaper equipment for the synthesis of three-dimensional objects. The proposed technical solutions expand the functionality of the equipment by implementing both layer-by-layer (horizontal) synthesis and volumetric, vertical or mixed horizontal–vertical, synthesis of parts.

Vegetable oils and animal fats are considered as base materials for the development of biodegradable lubricants. Classification of such materials was carried out using the Ward method based on the Euclidean distance, followed by refinement by the k-means method based on the physico–chemical properties. The selection of a material with the optimal characteristics was carried out using the TOPSIS method. Based on the calculated coefficients of relative closeness to an “ideal” material, a rating of lubricants was built, among which rapeseed oil is of the greatest interest. The comparative tribological characteristics of vegetable oils with the best ratings are presented. It is shown that vegetable oils are not inferior to mineral and synthetic oils. The ranking results can be used in further fundamental and applied research on the development of biodegradable lubricants.

A solution to the problem of determining the components of the cutting force and the cutting temperature when turning an aluminum matrix cast composite material is presented. The components of the cutting force and the cutting temperature when processing an aluminum matrix cast composite material with a hard alloy were taken as the optimization parameters. The studies were carried out using a specially designed experimental setup that consists of a lathe and a bench for recording, monitoring, and analyzing dynamic processes in the form of a signal from the cutter during turning. The computer and mathematical processing of the results obtained was carried out using the least squares method, which made it possible to derive the calculation equations to determine the factors under study. The optimal values of the factors corresponding to the optimal cutting force components and the corresponding cutting temperatures are determined.

The Gough–Stewart platform has occupied an important place in the manufacturing and scientific industries, making it possible to facilitate various production cycles or conduct necessary research. Its development makes it possible to solve newer and more complex problems or facilitate the implementation of existing ones. This article considers a modification of the classical platform; considers solutions to direct and inverse kinematics problems; implements a visualization program and a control algorithm, both a physical model of the platform and a virtual one; and estimates the parameters of the platform. Direct and inverse kinematics problems are one of the main problems that describe the platform; on their basis, it is possible to consider the behavior of the platform in various configurations of the given parameters. The visualization program allows one not only to view the behavior of the platform without the need to use a physical model of the platform, but also to control the real platform by transmitting the appropriate signals to the control circuit.

The tasks of forecasting a possible scenario of unintentional destructive impacts (mass impacts like voltage fluctuations, industrial electromagnetic interference, natural impacts) on a distributed automated control system are discussed. Analytical relationships are proposed to assess the consequences of such destructive impacts (signal transmission systems, communication systems). One of the possible scenarios of such impacts on the system is considered, taking into account the distribution of the intensity.

Methods have been developed for monitoring and diagnosing the degree of wear and loss of the geometric shape of surfaces. A selection of technological routes was carried out for the complex restoration of working surfaces of large-sized products using electrophysical energy sources during surfacing of powders and wires. It has been shown that the cost of major repairs when restoring a screw shaft is, on average, two times lower than manufacturing a new one. It is important to monitor regularly the degree of wear of shaft turns and their local restoration using surfacing materials and technologies.

The technology of laser impact welding of a thin aluminum plate with a stainless steel plate is discussed. Finite element simulation of the laser impact welding technology was conducted using the ABAQUS package. The results showed that the quality of the weld mainly depends on two parameters: the energy of the laser pulse and the initial distance between the plates. Conditions were established under which parameters of laser impact welding can be used to weld an aluminum plate with a stainless steel plate. The distributions of plastic strains and temperatures along the weld were obtained.

In this paper, a mathematical model of nonlinear aeroelastic oscillations of a disk that has a suspension with hardening cubic nonlinearity and interacts with a layer of viscous gas pulsating due to a specified disturbance on its contour is presented. An asymptotic analysis, which made it possible to reduce the initial model to the generalized Duffing equation, based on the solution of which the main aeroelastic response of the disk and its phase shift were found using the harmonic balance method, was carried out. The characteristics in particular cases provide a transition to an incompressible viscous fluid and a linear elastic suspension, while their numerical study made it possible to establish that the compressibility of the gas leads to an increase in the values of the resonant frequencies and an increase in the amplitudes of the disk oscillations. Calculations showed the possibility of suppressing unstable oscillations of the disk near resonant frequencies by changing the thickness of the gas layer. The obtained results can be used to study the dynamics of gas and liquid dampers and supports, as well as sensitive elastic elements of pressure sensors.

During engineering blasting operations, various man-made elements (particles) can be formed from the structure due to the impact of an explosion, which, as experimental data show, can have a completely arbitrary shape and a fairly large mass and speed. This article is devoted to consideration of the ballistics of elongated elements and the derivation of the calculated dependencies that allow one to estimate the trajectory of their movement.