Journal of Machinery Manufacture and Reliability最新文献

Buckling and ultimate failure loads for hybrid composite plates with different reinforcement structures under compression and shear loading are studied. The critical buckling loads and load-bearing capacity of hybrid plates under compression, shear, and their combined action are determined. The influence of the structural parameters of hybrid compositions on the postbuckling behavior and failure is shown; the ways of increasing the efficiency of combining heterogeneous layers under combined compression and shear are revealed.

A modern approach to personalized recommendation systems is presented, combining graph neural networks GNN with RL reinforcement learning methods. The GNN model is optimized for recommendation systems and is trained on vector representations of users and products, which are used to generate an initial list of recommendations that are fed into the RL model. Particular attention is paid to the architecture and operation of the integrated GNN-RL model. The results of experimental studies demonstrating the effectiveness of the proposed approach are presented.

The foundational aspects of fixation theory are updated, and a revised composition of bases is introduced: mounting, guiding, supporting, double guiding, double supporting, and triple supporting. These bases combine into five sets, each implementable through explicit or hidden bases or their combinations. This study finds that using sets of hidden bases poses significant challenges for object fixation, characterized by the need to determine the positions of support points by contact points on the object, which is achieved through mounting elements. When using a hidden base, the position of the support point is defined by the self-centering mechanism through contact points with the object to be based. Various design schemes for fixation and centering of objects using sets of hidden bases in self-centering mechanisms are considered.

The implantation of nanoparticles into materials using laser shock waves is an advanced method of surface strengthening of light metals and alloys. The strengthening is based on a combination of plastic deformation caused by the well-known laser shock peening and the high mechanical characteristics of solid nanoparticles. This article discusses specific interconnections between the strengthening mechanisms and the properties of the surface processed by laser shock waves. When such a technology is used, the strengthening effect is found to be provided by two main factors: the gradient microstructure caused by plastic deformation and the gradient depth distribution of implanted SiC particles. Three competing mechanisms affect the strengthening when a laser shock wave is applied to gradient reinforced layers: dispersion strengthening with SiC nanoparticles, grain refinement, and dislocation strengthening. The contribution of each strengthening mechanism to the total strengthening was studied using a modified Clyne computational model.

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 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 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.