Journal of Machinery Manufacture and Reliability最新文献

This article considers the use of artificial neural networks to analyze various defect combinations in removable load-handling devices and make decisions regarding their continued suitability for use. Statistical databases of expert assessments are used to train the artificial neural networks. An artificial neural network model has been developed that takes into account various defect combinations based on the deviation of the geometric parameters of the removable load-handling device from design values. It can be used to assess the performance of various types of removable load-handling devices, consisting of elements considered in the input layer of the neural network. The influence of the operating factors of removable load-handling devices on the confidence levels for determining their technical condition is demonstrated.

Challenges in the robotization of monitoring and cleaning hard-to-reach areas in the annular space of pipe-in-pipe (PIP) heat exchangers, between a submersible borehole pump and the casing and between the containment shell and the installed stay cable in the course of the construction of cable-stayed bridges are considered. A new concept for a universal adaptive robot with a parallel structure capable of operating over a wide range of annular space gaps is presented. The advantages of this robot compared to the existing systems are demonstrated.

In the mathematical modeling of the crystallization process, the results of a numerical experiment were used, in which a banded structure of the initial stage of the process was discovered, the mechanism of which is diffusion stratification. Qualitatively, this is consistent with the natural experiment. In the terminology of G.I. Barenblatt, the process is related to flow of the transformed state in the initial stage of crystallization before the formation of the dendritic structure. The universality of the principles of mathematical modeling and the relationship between critical processes of destruction, sintering of materials, and crystallization of binary alloys based on their physical commonality is shown.

An analysis of the use of numerical–analytical methods for modeling diagnostics and prediction of failures of digital twins for specific applications in maintenance and repair in various industries is presented. The relevance of this work is determined by the need to create highly detailed physical models of units and assemblies of mechanical engineering products, allowing the study of wear and failure processes under conditions of dynamically changing external factors. The methods used, the results obtained, the agreed conclusions, and open problems are considered. An assessment of the reliability and demonstrativeness of the studies reviewed is given. The results obtained are of interest to technical researchers and specialists involved in the management of complex technical systems.

The rotational stability of a symmetrical rigid rotor with simultaneous whirling in gas-dynamic foil bearings is investigated on an analytical level. Velocity patterns are formulated with respect to the destabilizing effect of lubrication, which is much more significant for forward whirl mode of the rotor. When the rotor loses rotational stability and undergoes forward whirl, a case of self-oscillations is considered, accompanied by dry friction against the bearing leaves in the form of backward whirl. Here, it is established that the self-oscillation mode does not depend on imbalance. Therefore, all the results initially obtained upon the simplification that the rotor is balanced are valid when the rotor is unbalanced, too. It is shown that forced oscillations caused by imbalance, on the contrary, depend on self-oscillations. The applied potentialities of the developed method for analyzing such rotor systems are demonstrated.

A detailed examination of the reliability requirements for hydraulic fracturing fleet equipment and reviews of industry-wide reliability metrics used abroad for reliability calculations are provided. The main types of failures of high-pressure pumps and drive systems are analyzed, and the causes of wear and defects that arise under aggressive operating conditions are explained. A methodology for calculating the reliability of the Russian hydraulic fracturing fleet is described and validated through field tests. An overview of recommendations for improving reliability is presented: the use of high-strength materials, modular designs, the implementation of automated control systems, and predictive maintenance enabled by comprehensive condition monitoring. This article synthesizes current approaches to ensuring the reliability of domestic hydraulic fracturing fleets, contributing to import substitution and increasing the efficiency of oilfield service operations under Russia’s harsh climatic conditions.

The problem of rolling an elastic ball on the surface of a viscoelastic layer in the presence of a thin layer of lubricant separating them is considered. The viscoelastic layer is located on a rigid base. The one-dimensional Kelvin model of a viscoelastic solid is used as a rheological model of the viscoelastic layer. The influence of viscoelastic properties of the coating on the pressure in the lubricating layer and its thickness was investigated.

Monitoring the accuracy and performance of laser rangefinders without the use of extended testing grounds or reflective targets is an urgent metrology challenge. We examine the methods and devices for testing laser rangefinders not involving testing grounds, which include optical range simulators, fiber-optic delay lines, and electronic simulators. Their advantages, limitations, and applications are discussed. A matrix of possible technical solutions is constructed and analyzed. The research conducted allowed us to evaluate state-of-the-art methods and devices for testing laser rangefinders which eliminated the need for extended testing grounds with reflective targets.

The influence of the electron component on the plasma dynamics of jets escaping from electric propulsion jet engines and liquid propulsion jet engines is examined. It is shown that in both cases a positively charged jet propagates surrounded by an electron cloud. Electrons significantly affect the distribution of potential and other parameters in the jet; they can initiate oscillatory processes and instabilities, and affect the motion of heavier particles—ions—through self-consistent fields.

Tests of a wire rope vibration isolator are conducted at various loading angles. The corresponding experimental diagrams are analyzed. It is shown that at certain loading angles the hysteresis loop in the diagram has an asymmetric shape. To account for this effect, it is proposed to estimate the effective stiffness coefficient of the vibration isolator using linear loop interpolation. Calculations show that estimating the stiffness using the proposed method yields lower coefficient values compared to the traditional method.