Journal of Machinery Manufacture and Reliability最新文献

The basic principles and approaches to automation of the tribological testing process are outlined. A prototype device for testing friction pairs in real time is designed and proposed. The results of tribotechnical tests of a life-limited connection of a hydrostatic transmission under optimal and design loads are presented.

The high-speed process of laser impact welding is examined. Finite element modeling of the laser impact welding technology is carried out using the Euler thermomechanical method, where the pressure in the shock wave is taken as an external effect. With the help of the developed model, the distributions of rapidly changing velocities along the length of the plates, shear stresses, plastic strains, and temperatures during the entire laser impact welding process were determined. It is shown that, during welding of this type, there is no effect of melting the plates.

The possibility of using the hierarchy analysis method to select features and criteria in morphological analysis is discussed. The possibilities for solving problems of collection, analysis, evaluation, and selection of technical solutions are specified. The difficulties or impossibility of creating accurate mathematical models of complex technical systems at the technical proposal stage leads to the need to make decisions under conditions of uncertainty. To solve this problem, the hierarchy analysis method is used. The formulation and method of solving the problem are given. The advantages of the presented algorithm are considered. Its use makes it possible to increase the validity of decisions made during morphological analysis and thereby to increase the efficiency of research and increase the technical level of the technical systems synthesized.

The electrical expslosion of a bridge made of the lead–tin alloy POS-60 in an air atmosphere is investigated experimentally. The electric discharge was initiated using a PIV-100M standard capacitor-based blasting device. Based on the analysis of oscillograms of the electric current and voltage drop across the bridge, the resistance of the bridge and the power of Joule losses therein depending on time have been determined. In the model approximation, the mass of the exploding part of the bridge and the specific energy coefficient of the resistance of the bridge material before the onset of melting have been obtained. This approach can be used to find the optimal dimensions of the bridge, to determine its thermophysical parameters in the course of an electric explosion, and to study the electrical properties of other low-melting materials that are promising for making a safe industrial detonator.

The prospects of development of technological equipment complexes have been considered. It is proposed to start designing mechatronic systems of machine tool complexes by analyzing information connections in hybrid manufacturing, which includes traditional and additive technologies. It is recommended to use sequences of transfer criteria to analyze the processes of forming material structures and surface layers of products during thermomechanical and electrophysical processing. The organization of feedback in managing technological equipment using additional energy flow effects is demonstrated. It is suggested to choose numerical control and design machine tools as mechatronic complexes, taking into account direct and feedback connections in the technological system. The complex of hybrid technological equipment and its modules and units is recommended to be designed as computer peripheral devices, built on the architecture of computers.

The article discusses the problem of structural synthesis of mechanisms designed from planar- and screw-type kinematic chains. Using the example of the simplest zero-mobility groups — planar dyads (two-bar groups) and screw monads (one-bar groups) — we demonstrated a synthesis algorithm, which consists of setting these groups between two links, combining them into a closed kinematic chain. When we fix any of the links in such a chain, we obtain a workable mechanism. This algorithm considers two possible options for the relative arrangement of planar- and screw-type kinematic chains. Based on the developed algorithm, we synthesized a family of five-bar planar-screw one-DOF mechanisms. We confirmed the competence of the presented algorithm by performing a mobility analysis of one of the synthesized mechanisms.

The results of semianalytical calculation of the critical buckling loads and load-bearing capacity of laminated composite panels having different geometric shapes in plan in the course of loading with compressive and tangential forces in the plane of the layers are presented. The stability problems of orthotropic layered plates with variable geometric parameters have been solved by the Rayleigh–Ritz method with approximation of the deflection function by orthogonal Krylov polynomials. The effect of shape, the method of fastening the panels, and the arrangement pattern of reinforcing fibers in the layers of the composite has been studied. Rational reinforcement patterns that correspond to the highest critical buckling load for nonrectangular and shallow curved panels have been revealed. The load-bearing capacity under supercritical strain has been assessed based on the Tsai–Wu strength criterion.

The possibility of using a more economical process—intense plastic deformation of superalloys by pressure with torsion under isothermal conditions—is substantiated. It is shown that in this case the critical load on the tool is significantly reduced and the single-transition process of deformation accumulation necessary for uniform grain refinement in the material of large superalloy workpieces is ensured. A die design has been proposed for implementing the torsional pressure method for producing gas turbine engine disk blanks under isothermal conditions.

The results of testing the technology for modeling crack development using the finite element analysis in a three-dimensional formulation are described. The results are compared with known experimental data, and a number of inconsistencies are identified and explained. The forecasts and recommendations for improving the corresponding software are given.

The development of technological processes for manufacturing machine tool parts with wear-resistant coatings deposited during their manufacturing is discussed. The performance features of tool parts during mechanical treatment of workpieces made of hard-to-cut materials is analyzed, and the use of gas-thermal coatings is substantiated to ensure the operational and technical characteristics of the products under consideration.