Journal of Machinery Manufacture and Reliability最新文献

For the first time, based on correct experiments that exclude the negative effects of temperature variability and mutual misalignment and/or axial displacement of the rings, torque values for the rotating resistance forces depending on time have been obtained for a single-row radial ball bearing loaded with a radial force. An analysis of the experimental studies on the torque of the rotating resistance forces of single-row radial ball bearings conducted by J. Goodman, R. Stribeck, and others is presented. It is shown that the experimental dependences obtained at the Mechanical Engineering Research Institute of the Russian Academy of Sciences (IMASH RAN) representing the inherent characteristics of the studied ball bearing can be used for an integrated assessment of its quality.

The nonlinear dynamics of spacecraft power structures in the form of closed cylindrical shells under the action of an external alternating load are investigated. To study the nonlinear dynamics, a mathematical model of the described structure was constructed taking into account the geometric nonlinearity according to the T. von Karman model and the Kirchhoff–Love kinematic hypothesis. The resulting system of differential equations is reduced to the Cauchy problem using the Bubnov–Galerkin method, after which it is solved using the Runge–Kutta method in time. It is shown that the transition of oscillations of a closed cylindrical shell from harmonic to chaotic occurs according to a combination of the Feigenbaum and Ruelle–Takkens–Newhouse scenarios.

The prospects for using microservice architecture in the development of flexible automated production control systems at mechanical engineering enterprises are considered. Methods for designing and implementing automated production control systems based on microservice architecture are discussed, and the advantages and disadvantages of this approach are shown. A prototype of a flexible automated system, developed using the Java language and the Spring framework, was proposed for the butt welding section of a metal disc production plant. The developed concept is a set of software modules in the form of microservices for independent data processing at each stage of the production process, which increases the fault tolerance and reliability of the entire system.

The problems of manufacturing low-stiffness parts for aircraft engineering, which have enormous advantages due to the implementation of power frame and skin elements in a single part, reduced labor intensity of processing and assembly, etc., are considered. A comparative analysis of methods for reducing residual stress is carried out, and the conclusion is reached that the most promising method for reducing residual stress is considered to be the one based on changing the cooling rate during the hardening process. General approaches to solving problems of residual stress control by the proposed method are formed based on consideration of isothermal decomposition diagrams. A ranked objective function for optimizing the quenching process to minimize the level of thermal residual stresses is presented, and boundary conditions for constructing possible technological processes for solving the optimization problem are determined.

In various industrial sectors, including energy, transportation, and other industries, a significant amount of diverse equipment operates, which is a system consisting of one, two, or bundles of pipes streamlined by liquids or gases. The flow of fluid passing through tube bundles, such as those in heat exchange equipment, causes them to vibrate. The efficiency of such pipeline systems largely depends on the correct design, installation, and operation.

This paper considers compressive thermomechanical loading and its effect on high-temperature strength characteristics of single-crystal SLZhS5-VI high-temperature nickel alloy. This treatment has been shown to considerably improve ductility (relative elongation and relative contraction) of the alloy at room and elevated temperatures and increase its time to rupture and creep resistance at a temperature of 900°C owing to the decrease in the density of casting defects (micropores and microcracks) as a result of the lower strain rate.

We have studied diamond-like carbon coatings produced by vacuum ion-plasma deposition. The coatings were doped with Ti ions via arc evaporation of a titanium cathode in parallel with laser arc evaporation of carbon from a graphite cathode. The titanium-doped diamond-like coatings were grown on 40CrNi steel substrates with a sorbite structure. The Ti content of the metal–carbon coatings thus prepared was in the range 1.5–5.5 wt %. The coating thickness was widely varied in our experiments, in the range δ = 0.5–4.5 μm. The effect of the parameter δ on tribological characteristics of the coatings was one of the key aspects of this research. The structure of the coatings was studied by high-resolution electron microscopy and their mechanical properties were studied using continuous indentation. The tribological properties of the coatings were assessed in ball-on-disk sliding friction tests on a tribometer at friction loads in the range F = 1–10 N. In analyzing the experimental data obtained, we used a computational analysis model which allowed us to construct critical state diagrams of various materials and coatings. The results demonstrate that such diagrams can be used for reliably predicting the minimum coating thickness δ_min needed for preventing premature failure of coatings in tribological tests. In addition, titanium doping of diamond-like carbon coatings (in the range of Ti concentrations studied) was shown to help stabilize the coating thickness: no spontaneous cracking of the coatings was detected at thicknesses of up to δ = 4.5 μm, and their microstructure remained sufficiently uniform, without any signs of formation of secondary carbide phases.

One of the peculiarities of bending tests of polymer fibrous composites is the need to use cylindrical supports of significant radius to avoid indentation and “nipping” of a sample with low transverse strength. In the refined formulation, a number of effects of the use of cylindrical supports are considered, the influence of which is strictly estimated by expansions in small parameters. The limits of deflection, sample sizes, and support radii are established, when, with a given accuracy, the specified effects can be neglected when determining Young’s modulus and the ultimate strength for normal and shear stresses. It is shown that when finding the interlayer shear modulus, the error that occurs when sample rolls off the supports can be significant; therefore, for the described method, the radius of the supports must be taken into account.

An approach to assigning rational machining modes for workpieces, based on the assessment of residual stresses, is considered. The advantages of the finite element modeling method for residual stresses arising during the cutting process are analyzed. The choice of the Johnson–Cook model, which describes the material deformation processes during machining, is substantiated. An analysis of the influence of technological parameters such as turning modes and the geometric parameters of a turning tool on the magnitude of residual stresses is carried out. An algorithm based on the finite element method, which allows for the assessment of residual stresses arising in workpieces during their turning, is presented.

Recently, the quality of equipment used in sugar beet production has been declining with continued operation, which is associated with the failure of key equipment components due to wear and exhaustion of their service life. An analysis of the performance of the technological equipment was conducted, identifying critically important units and assemblies that require restoration and reinforcement. Such measures will help reduce equipment downtime and increase its mean time between failures.