Journal of Machinery Manufacture and Reliability最新文献

The problems of the modern stage of operation of hazardous production facilities and other complex technical systems are examined. A graphical–analytical method for optimizing the frequency of monitoring at various levels is proposed. The results of modeling the program for ensuring the safety of hazardous production facilities and other complex technical systems using the mathematical apparatus of semi-Markov processes are presented. An analysis of the obtained results is carried out and substantiated conclusions are made.

The so-called edge impact in gear engagements when the transmission operates under skew conditions is studied. An approach is proposed, and on its basis, the problem is solved analytically. Calculation formulas are obtained for determining the impact force when the teeth enter engagement at an off-design point. The dependences of the impact force on the skew angle are obtained. It is shown that, with an increase in the skew angle, the dynamic component of the force decreases, and with an increase in the static load, it grows.

An analysis of the application of riveted joints is presented. The materials used for their manufacture and the results of studies on the computational and experimental investigation of upsetting rivets made from the VZh98 alloy are shown. The results of stress values arising in the cemented carbide inserts of the tool depending on the interference fit of the sleeve are presented. A comparative analysis of the force parameters of the process, determined through experimental and finite element studies, is given.

A material demonstrating the shape memory effect at deformation under preliminary rolling and annealing has been discussed. Strain hardening through cold work and cycling under load is studied. The effect of the texture of rolling and drawing on the mechanical and thermomechanical characteristics of the material is revealed.

The results of experimental estimation of the stiffness and damping of a wire rope vibration isolator for typical loading schemes are presented. The nonlinearity and anisotropy of the elastic-dissipative characteristics of the vibration isolator are studied. The possibilities and limitations of using finite element models of wire rope vibration isolators to obtain frequency response by means of computational experiments are analyzed.

This study develops an analytical model to determine residual stresses and surface roughness after the impact of multiple laser pulses. The effect of different parameters of laser shock peening on residual stresses, the depth of their occurrence, and the surface roughness have been studied for the V95 aluminum alloy. An increase in the laser power is found to influence the growth of compressive residual stresses, the depth of their occurrence, and surface roughness. When the laser beam radius increases, the depth of residual stress occurrence grows significantly. The growth of the overlap ratio causes an increase in residual stresses, while their occurrence depth changes slightly. During the design of the experiment, the maximum depth of compressive residual stresses and the lowest roughness can be reached by controlling the laser shock peening parameters.

A methodology for assessing external losses occurring at mechanical engineering industry enterprises is presented. Primary attention is focused on the fact how accounting for these losses promotes managing production risks. A comprehensive approach to the assessment of external losses that includes analyzing not only quantitative characteristics of defects, but also financial costs required for the elimination thereof has been proposed. Particular importance is given to plotting a Pareto diagram that makes it possible to reveal the most critical types of defects from the standpoint of economic consequences. Practical examples for applying the proposed methodology at real enterprises, as well as its impact on improving the efficiency of risk management, are considered.

This article is devoted to solving a problem related to wear of rubbing parts of power takeoff devices of fire trucks. Analysis of the causes of failure of power takeoff devices and of the factors affecting the wear of the contacting surfaces of parts is carried out. To reduce friction, it is proposed to use an antiwear additive developed on the basis of copper and tin stearates with the addition of artificial serpentine powder. Tribological tests of the developed composition were carried out; the results are presented in this article. It was revealed that the introduction of an antiwear additive into the base lubricant allows one to reduce the friction coefficient and wear intensity of contacting surfaces.

The reliability of borehole pumps in general and its individual components is ensured during their design and manufacture. It depends on the features of the design, on the quality of manufacturing of their constituent parts, the quality of the assembly of the borehole pump as a whole and their components, as well as a number of other indicators of the technological process. The level of reliability laid down during development and ensured by production is further determined by operating conditions and other operational factors. The relevant theoretical and experimental studies of the factors affecting the operation of a downhole pump have shown that it is possible to increase the reliability of the design and the efficiency of its operation by: (1) finding ways to protect friction surfaces from the impact of abrasive, ways to level the wear of rubbing pairs in different sections; improving the design of downhole pumps in general and finding the optimal combination of configuration of the elements of the units and their interfaces, which have stable operation in the appropriate operating conditions; (2) neutralizing the causes that cause complications in the operation of the downhole pump, and finding ways to eliminate them. To solve the tasks in the indicated direction, we have chosen a constructive-technological method. According to the above, a number of variants of borehole pumps, their components and parts were developed, including: borehole pump with a sealing element in the gap between the casing and bushings; borehole pump with cylinder rectifying device; borehole pumps with centering devices in two versions; borehole pump with forced suction valve; borehole pump with a rotating plunger; special plunger resistant to abrasive wear; downhole pump resistant to hydroerosive wear, downhole pump without volume loss of liquid and with forced filling of the cylinder; downhole pump for pumping gas–liquid mixtures; a valve assembly with a ball deflector and a downhole pump with elements with minimal hydraulic resistance. This article describes the design features of the proposed developments, the principle of their operation and the necessary calculations for their implementation.

The results of development of the methodology and program for numerical modeling of the process of fatigue failure of structural elements with surface mechanical damage (defects) such as guide scratches and marks are presented. The calculation includes two stages: Stage 1 includes modeling the process of defect formation as a dynamic elastic-plastic contact problem; Stage 2 includes fatigue calculation taking into account the influence of defects and residual stress fields arising during its creation. For a number of model examples, the distributions of residual stresses in defect zones and the dependences of the maximum residual stress on the cross sectional shape of damaging elements (of various configurations (rectangular, semielliptical, wedge-shaped) and their movement speeds are obtained, and the values of the minimum movement speeds of damaging elements at which the damage of the considered type is possible for a given cross-sectional configuration are established. The results of calculations of samples made of 17G1S pipe steel with defects for resistance to fatigue failure are presented.