Journal of Machinery Manufacture and Reliability最新文献

The role of neural networks in autonomous driving systems, focusing on the application of various neural network architectures such as the PointNet, dynamic graph CNN, recurrent, convolutional, and autoencoder neural networks, is considered. The advantages of using neural networks to process incoming sensory data, including cameras, lidars, and radars, are discussed, which can improve the safety and efficiency of autonomous vehicles. Specific tasks such as object recognition, glitch filtering, route optimization, and adaptation to changing conditions are considered. This paper highlights the need for further research and development of neural network algorithms to improve the reliability and robustness of autonomous systems in real-world conditions.

An important task in the theory of mechanisms and machines is to reduce the nonuniformity of rotation of the input link of cyclic machines. A traditional method for solving this problem is the installation of a flywheel; however, for equipment with large peak values of cyclic loads, the moment of inertia of the flywheel can become very high, which leads to an increase in the size and weight characteristics of the machine. This paper investigates, using the example of a piston compressor, the possibility of reducing speed fluctuations of the input link by means of a pair of noncircular gears installed between the engine shaft and the input shaft of the cyclic mechanism. These gears enable nonlinear torque transmission, increasing torque during the working stroke and decreasing it during the idle stroke of the machine. The dynamics of the piston compressor are analyzed, and the noncircular gears are synthesized based on the law of motion of the crank link. A comparative analysis is conducted on the reduction of speed fluctuations of the initial link achieved by installing either a flywheel or the designed noncircular gears.

An approach is used in this paper that allows for describing boundary conditions of the third kind under the influence of a heat source on the human body from the standpoint of asymptotic perturbation theory. A woven electric heater with the heat-generating elements made of carbon threads served as a source of perturbations. The obtained results made it possible to find a more accurate mathematical description of the physical processes that occur on the surface of a woven electric heater located directly on the human body. The theoretical justification of the proceeding thermal process confirms the possibility of simultaneous implementation both of thermal action using a woven electric heater and of tracking temperature changes on the surface of a woven electric heater taking into account the response to the impact from a person, which is a novelty. Based on this approach, a program that can be used to simulate thermal processes on the surface of woven electric heaters located on the human body was written. This paper is of interest to specialists involved in modeling processes that occur under the influence of heat sources on the surface of a human body as well as to developers of heating devices based on electrical heating fabric, physiologists, etc.

The results of an experimental study of the machining accuracy of a batch of samples with an internal cycloidal helical surface using the gerotor drilling method are presented. The results of this study allow judging the possibility of industrial application of the method under consideration and also show the economic potential in the implementation of the technology of gerotor drilling of holes with a complex profile in small-sized casings of single-screw pumps made of fluoroplastic. Experimental data have been obtained showing that gerotor drilling has sufficient accuracy to meet the technical requirements for the working surfaces of the gerotor pair of a single-screw pump.

Experimental studies of oscillations of the 18-m three-section concrete placing boom of an SB-126 truck-mounted concrete pump are performed. The test program included determination and analysis of boom oscillations in the vertical and horizontal planes, as well as its compression and torsion. The frequencies and forms of oscillations of the placing boom, dynamic loads in the boom metal structures, concrete pipeline and boom mounting bracket, and pressure in the hydraulic system of the central piston group and concrete mix in the concrete pipeline are determined.

An analytical model based on Hertz contact theory and Neuber plasticity theory, which is used to predict the values of residual stresses that arise in materials when using the laser shock peening technology, is developed. The developed analytical model was verified by comparing the values of compressive residual stresses with numerical and experimental data, which confirmed its performance. The analytical model developed makes it possible to create databases that will link the parameters of laser shock peening and the residual stresses obtained. When planning experiments, it will be possible to select laser shock peening parameters that will lead to the desired residual stress fields.

This article examines the design of a manipulator model with linear motors that are installed parallel to one axis, which makes it possible to increase the working area along one coordinate. The possibilities of this manipulator getting into special positions of various types are also considered.

The vibrations of a circular, thickness-symmetric three-layer sandwich plate under a local pulsed axisymmetric load are investigated. Thin load-bearing layers obey the classical Kirchhoff hypotheses. In a thicker lightweight filler, the Timoshenko hypothesis is adopted. The effect of temperature on the elastic parameters of the materials of the layer is taken into account. The solution to the initial-boundary value problem for a sandwich plate is obtained by expanding the sought functions in a series over a system of eigenfunctions. Transcendental equations are written out to find the corresponding eigenvalues; their values are given in Table 1. Calculation formulas for deflection and relative shear in the filler are obtained. The results of the numerical analysis are presented in the form of graphs.

The design and calculation of a working environment simulation stand for the in-plant testing of peristaltic pumping units is presented. Such a stand is developed to assess the durability and reliability of the structure through conducting tests under conditions as close to real as possible. In order to confirm the reliability and operability parameters of the structure, a strength calculation has been carried out. The results of the simulation make it possible to confirm the operability of the structure.

Modeling the friction and wear of carbon materials is a complex task, since the materials have unique properties such as high hardness, brittleness, and chemical inertness. In contact pairs, for example, metal–carbon material, complex physical and chemical processes occur, which are associated with the presence of wear products in the contact zone, high temperatures, and a number of other factors. Friction and wear of these materials play an important role in industry: machine tool and engine building, metalworking, and the creation of machine components and mechanisms for various purposes. Regression analysis in modeling friction and wear of carbon materials allows us to identify relationships between various factors influencing these processes. This is necessary for the prediction and optimization of parameters such as friction and wear reduction in various tribological systems, which allows predicting the behavior of the system under different conditions. These are necessary in the development of the materials and technologies under study, which can significantly increase their efficiency and durability.