Showing papers in "Journal of Machinery Manufacture and Reliability in 2017"
TL;DR: In this paper, a dynamic model of cylindrical grinding with a tool owning specified distribution of abrasive grains is proposed, and the surface geometry formed after a grinding wheel pass has been determined, the influence of the process dynamics on cutting forces and machined surface geometry has been taken into account.
Abstract: This paper proposes a dynamic model of cylindrical grinding with a tool owning specified distribution of abrasive grains. Cutting forces have been calculated, the surface geometry formed after a grinding wheel pass has been determined, the influence of the process dynamics on cutting forces and machined surface geometry has been taken into account, and the effects of cutting condit on vibrations being generated in the process of grinding have been investigated.
20 citations
TL;DR: The problem of optimizing a distribution of carbon fiber content in hybrid glass/carbon fiber reinforced (GFRP/CFRP) structural elements of plane, statically determinate regular elastic truss structure is discussed and a modification of genetic algorithm combined with the method of mathematical induction is proposed.
Abstract: In this paper the problem of optimizing a distribution of carbon fiber content in hybrid glass/carbon fiber reinforced (GFRP/CFRP) structural elements of plane, statically determinate regular elastic truss structure is discussed. A modification of genetic algorithm combined with the method of mathematical induction is proposed. A criterion of structural materials cost minimization while satisfying elastic strength requirements is used as an optimality criterion.
19 citations
TL;DR: In this paper, an analysis of the applicability of metal-based certification methods to composite structures, as applied to materials and processes qualification, is presented and the major drawbacks of the above approach, such as the large amount of testing required and the impossibility of achieving the required weight efficiency of aircraft, are shown and the basic principles of a composite-friendly certification approach are formulated.
Abstract: An analysis of the applicability of metal-based certification methods to composite structures, as applied to materials and processes qualification, is presented. The major drawbacks of the above approach, such as the large amount of testing required and the impossibility of achieving the required weight efficiency of aircraft, are shown and the basic principles of a composite-friendly certification approach are formulated. The necessity to capture the impact of manufacturing factors on structural performance on all scales of the Building Block is stressed. A brief review of domestic studies on simulation of the influence of process parameters on the strength of structures as applied to processes currently used in the aviation industry is offered.
14 citations
TL;DR: In this paper, the problem of minimizing critical events, the combination of which lead to accident situations in robotic welding as part of man-machine production control systems has been considered, and models, algorithms, and software and hardware tools for solving it have been developed.
Abstract: The problem of minimizing critical events, the combination of which lead to accident situations in robotic welding as part of man–machine production control systems has been considered. The statement of the problem has been adduced, and models, algorithms, and software and hardware tools for solving it have been developed. The solution of this problem will improve the accuracy and quality of operations and reduce losses from the downtime of the welding equipment.
12 citations
TL;DR: In this paper, the authors studied the bending oscillations of walls of conduit on Winkler foundation under the influence of pulsating flow of viscous liquid in hydraulic drives, assemblies, and devices.
Abstract: Bending oscillations of walls of conduit on Winkler foundation under the influence of pulsating flow of viscous liquid have been studied. The statement and solution of hyper-elasticity problem have allowed analytical expressions for channel wall bends and pressure in liquid to be defined, as well as the distribution functions for bend amplitudes and pressures along the channel to be plotted. The performed calculations showed the significant impact of taking into consideration the elastic compliance of the channel foundation on the bend amplitude of channel walls and pressure in the channel. The obtained results present the possibilities of studying the dynamic processes conditioned by the interactions of elastic structural elements with viscous liquid in hydraulic drives, assemblies, and devices.
12 citations
TL;DR: In this paper, an iteration algorithm has been developed for the design of the reinforcement structure of composite plates of a arbitrarily shape with any principles in the change of boundary conditions, and the correctness of the algorithm for the plot of rational fiber placement trajectories, assuming their equally stressed state, which is equivalent to the exclusion of shear stresses at the fiber-matrix interface, has been rationalized.
Abstract: The correctness of the algorithm for the plot of rational fiber placement trajectories, assuming their equally stressed state, which is equivalent to the exclusion of shear stresses at the fiber–matrix interface, has been rationalized. An iteration algorithm has been developed for the design of the reinforcement structure of composite plates of a arbitrarily shape with any principles in the change of boundary conditions. As an example, the fiber trajectories that “surround” the hole, which is free or loaded through the steel bushing, have been presented, as well as the trajectories in accordance with a nonuniform distribution of the stresses applied to the plate.
12 citations
TL;DR: In this paper, the direct linearization of mixed nonlinear forces is used to analyze nonlinear oscillatory systems, in contrast to well-known methods of nonlinear system analysis, which allow computational cost (time and effort) to be reduced by several orders.
Abstract: This paper describes the method of the direct linearization of mixed nonlinear forces, which is used to analyze nonlinear oscillatory systems. This method has been compared with other methods in order to demonstrate their resemblance in terms of the practical results. In contrast to well-known methods of nonlinear system analysis, direct linearization methods allow computational cost (time and effort) to be reduced by several orders, which considerably increases their effectiveness.
11 citations
TL;DR: In this article, a method has been proposed for determining the parameters of the preforms and the process variables to manufacture them and the method insures the specified thermomechanical characteristics of the composite structure.
Abstract: Technology for manufacturing preforms for tubular components from composite materials for aerospace engineering by radial braiding has been considered. A method has been proposed for determining the parameters of the preforms and the process variables to manufacture them. The method insures the specified thermomechanical characteristics of the composite structure.
10 citations
TL;DR: In this article, the features of applying the velocity and force criteria of proximity to specific positions to the mechanisms of parallel structure with a fewer than six degrees of freedom have been considered.
Abstract: The article is devoted to the features of applying the velocity and force criteria of proximity to specific positions to the mechanisms of parallel structure with a fewer than six degrees of freedom. Problems of both theoretical and computational nature and variants of their solutions have been considered.
10 citations
TL;DR: In this paper, an automated control system of the cutting mode where temperature is monitored by a thermocouple is described, based on a fuzzy algorithm of self-calibration that aims to provide calculation accuracy for the voltage at the transistor control gate.
Abstract: This article describes an automated control system of the cutting mode where temperature is monitored by a thermocouple. The system is based on a fuzzy algorithm of self-calibration that aims to provide calculation accuracy for the voltage at the transistor control gate, the drain of which is connected to cooling Peltier element. The algorithm operation and total system have been numerically simulated.
9 citations
TL;DR: In this article, the authors deal with the problems of kinematic and force analysis of a technological robot with a parallel structure, which is a development of the well-known METROM scheme that corresponds to five degrees of freedom.
Abstract: The paper deals with the problems of kinematic and force analysis of a technological robot with a parallel structure, which is a development of the well-known METROM scheme that corresponds to five degrees of freedom. In contrast to the prototype, this mechanism only has three kinematic chains, which leads to an increase in the working area due to a decrease in the possibility of mutual interference between the kinematic chains.
TL;DR: In this article, the direct positional problem for the parallel structure mechanism of simultaneous relative manipulation has been solved and the operating space of the mechanism has been defined, and the direct and indirect positional problems for the mechanism have been considered.
Abstract: Synthesis problems of handling mechanisms of simultaneous relative manipulation have been considered. The direct positional problem for the parallel structure mechanism of simultaneous relative manipulation has been solved. The operating space of the mechanism has been defined.
TL;DR: In this article, the problem of calculating the lower confidence limit for the reliability function and the other main indices, such as the mean time to failure (mean lifetime) and the guaranteed (gamma-percentile) lifetime of a system based on the reliability test results has been considered.
Abstract: The problem of calculating the lower confidence limit for the reliability function and the other main indices, such as the mean time to failure (mean lifetime) and the guaranteed (gamma-percentile) lifetime of a system based on the reliability test results has been considered. The problem is solved under the general nonparametric assumption of the monotonically increasing failure intensity function (aging) of a system. A series of expressions for the lower confidence limits of the aforementioned main reliability indices has been derived.
TL;DR: In this article, the LS-STAG method is used for numerical simulation that makes it possible to calculate using rather coarse meshes, and the typical dependences of coefficients of drag force and lift force on the time are presented.
Abstract: The flow around two circular airfoils positioned side by side (across the stream) at different distances between the airfoils is considered. The LS-STAG method, which belongs to the class of immersed boundary method is used for numerical simulation that makes it possible to calculate using rather coarse meshes. Stationary and trigger flow regimes have been simulated, as well as the patterns of flow with synchronization of two vortex trails in-phase and in anti-phase. For each regime, the typical dependences of coefficients of drag force and lift force on the time are presented. The obtained results are in good agreement with the known experimental and computational data.
TL;DR: Parallel-structure mechanisms with four degrees of freedom and four kinematic chains are discussed in this paper, where the main result is the synthesis of a new parallel-structured mechanism and a screw analysis of constraints imposed by the chains.
Abstract: Parallel-structure mechanisms with four degrees of freedom and four kinematic chains are discussed. The synthesis of these manipulators were performed using a device of closed screw groups. This approach allows avoiding complex equations of synthesis and analysis of singularities. Kinematic chains may impose equal constraints or different constraints, and each may contain a drive. The main result of this article is the synthesis of a new parallel-structure mechanism and a screw analysis of constraints imposed by the kinematic chains.
TL;DR: In this paper, an approach based on the multicriterion principles, cluster analysis, and the theory of sets is proposed for the structural synthesis and parametric optimization of the design of transportation and technological systems.
Abstract: The article deals with a complex application for the structural synthesis and parametric optimization of the design of transportation and technological systems and evaluation of innovative engineering solutions based on advanced morphological approach. The approach is based on the multicriterion principles, cluster analysis, and the theory of sets. The article provides examples of application of the proposed approach to the selection of the process of manufacturing of long hollow shafts of gas turbine engines from heat-resistant alloys and steels under isothermal conditions, determination of the optimal values of the resonant transducer for reducing longitudinal vibrations of a mechanical system, and synthesis of transportation systems. The application of the advanced morphological approach enables the refining and ordering of the structuring of the problems to be solved. The degree of the validity of the adopted solution is considerably increased by applying to every variant of the selected structure the method of parametric optimization of the LPS search implemented by a separate algorithm, which enables enhancement of the quality (technological level) of the technical systems under design.
TL;DR: In this article, the authors propose criteria and methods for estimating the adaptive properties of mechanical systems, such as sliding bearings, worm gears, and internal combustion engines, under the conditions of using the film-forming lubricants.
Abstract: The article proposes criteria and methods for estimating the adaptive properties of mechanical systems, such as sliding bearings, worm gears, and internal combustion engines. The examples of estimating the adaptation effects under the conditions of using the film-forming lubricants have been given.
TL;DR: In this article, the mathematical model of the electric-power DC drive for actuating links of a tripod manipulator with self-breaking transmission has been considered and analytical conditions of lack of dynamic jamming the drive have been obtained.
Abstract: The mathematical model of dynamics of the electric-power DC drive for actuating links of tripod manipulator with self-breaking transmission has been considered. Analytical conditions of lack of dynamic jamming the drive have been obtained.
TL;DR: In this article, an engineering system of complex real machine assembly is considered that, in contrast to a conventional assembly, has additional degrees of freedom, i.e., those that modify the dynamics of the basic degree of freedom on average.
Abstract: An engineering system of complex real machine assembly is considered that, in contrast to a conventional assembly, has additional degrees of freedom. These degrees of freedom are considered to be latent, i.e., those that modify the dynamics of the basic degree of freedom on average. According to this approach, the authors obtained an averaged equation that has the form of a classical equation of a simple real assembly, but contains an additional moment of load that considers resonance phenomena. The derivation of the equation is exemplified by a vehicle that moves along an uneven road.
TL;DR: In this article, the authors compared the bending flexibility of shaped beams of the constarea class and branching composite structures that resemble a treetop with a constant sum of the areas of sections of the branches.
Abstract: The analogy of the bending flexibility of shaped beams of the constarea class (with a constant area of the cross section) and branching composite structures that resemble a treetop with a constant sum of the areas of sections of the branches (Leonardo’s rule) has been studied. Ideally, profiling or branching provide threefold growth in flexibility while retaining strength, i.e., a threefold increase in the accumulated elastic energy for the fixed load and mass of the elastic element. It has been shown that the use of the fiberglass in these elastic elements enables one to reduce their mass by approximately 20 times compared to the steel analog. The limitation of the possibility of use of the linearized bend equation for the shaped beams has been specified. The efficient use of branching composite elastic elements is possible in space-based structures due to their light specific weight and extremely low energy consumption when producing parts from polymer composites, which allows them to be produced directly in orbit.
TL;DR: In this paper, the efficiency of vacuum carburization in a rational process environment with the advantages of automated process equipment is demonstrated, and the advisability of building a specialized enterprise to produce domestic vacuum plants as a basis for modernizing the thermal process is shown.
Abstract: The article demonstrates the efficiency of vacuum carburization, which combines the rational process environment with advantages of automated process equipment. The equipment offers an opportunity to carry out carburization jointly with dry quenching in a high-pressure nitrogen flow. The advisability of building a specialized enterprise to produce domestic vacuum plants as a basis for modernizing the thermal process has been shown.
TL;DR: In this paper, the failure of the KAMAZ truck spring during the cold operation period under the climatic and natural conditions of the North was studied taking the metal degradation in the zones of different loading into account.
Abstract: Forecasting of the residual life of machine and structure elements requires consideration of the changes of the metal condition until it achieves its critical states. The failure of the KAMAZ truck spring during the cold operation period under the climatic and natural conditions of the North was studied taking the metal degradation in the zones of different loading into account. The structural damage was estimated using the microhardness and porosity parameters. The physical mechanisms that change the microhardness and the formation of the pore system in the spring steel were analyzed. It is shown that a deviation of the value of the metal microhardness from the normal distribution law is observed in the zone of development of a fatigue crack in the spring. Satisfactory resistance of the spring material to the development of a failure is revealed under the considered temperature–load conditions. A materials-engineering analysis confirmed the role of the road conditions as a more significant destructive factor during the working of the spring in the permafrost zone compared to the factor of the low temperatures.
TL;DR: In this article, the reliability indices of a nonrepairable one-shot item based on small statistical samples using a priori information has been presented, which consists of formulating cases when the F test should be used as well as the t test, and the proposed simple method for determining the lower limit of the complex reliability index.
Abstract: The evaluation of the reliability indices of a nonrepairable one-shot item based on small statistical samples using a priori information has been presented. The novelty of the obtained results consists of formulating cases when the F test should be used as well as the t test, and the proposed simple method for determining the lower limit of the complex reliability index.
TL;DR: In this paper, the authors have investigated processes of wave mixing in oscillatory-type power plants and presented the results in the paper, where the flow in the power plant has been simulated by solving a set of 2D nonstationary Navier-Stokes equations for viscous uncompressible liquid.
Abstract: We have investigated processes of wave mixing in oscillatory-type power plants and presented the results in the paper. The flow in the power plant has been simulated by solving a set of 2D nonstationary Navier–Stokes equations for viscous uncompressible liquid. The flow field was formed by blade vibration and, as a result, the triangle deformed mesh has been used. The marker method has been used as the basic method for calculating the evolution of the admixture. The information of computations is processed using special criteria of the mixture quality. The influence of frequency and amplitude on the mixing intensity has been investigated. The consumed power has been estimated. The obtained information forms a basis for determining optimal modes of power plant operation in terms of power consumption–mixing efficiency.
TL;DR: In this article, a renewal function for a simple restorative (renewal) process, a comparison of three operating strategies according to the criterion of minimal cost intensity and using the method of moments to find point estimates for the parameters involved in the mixture is considered.
Abstract: A number of problems in the reliability theory as applied to technical systems is considered for the case when the time-to-failure values are distributed as a mixture of two exponential distributions. This consists of finding a renewal function for a simple restorative (renewal) process, a comparison of three operating strategies according to the criterion of minimal cost intensity and using the method of moments to find point estimates for the parameters involved in the mixture. The choice of the mixture is caused by the fact that its failure rate has a running-in period that is characteristic within the initial operation period of technical systems, whereas afterwards, the failure rate is almost constant. This distinguishes the considered mixture from the exponential distribution with a constant failure rate widely used in the reliability theory.
TL;DR: A spatial mathematical model for estimating the loading dynamics of articulated load-carrying structures for the entire set of technological operations of the mentioned machines is developed and an approach to the simulation of a stress-strain state of an assembled structure of articulation is outlined depending on the type of technological operation performed by the machine.
Abstract: Investigations were performed aimed at increasing the fatigue life of articulated load-carrying structures used in multioperational logging machines. A spatial mathematical model for estimating the loading dynamics of articulated load-carrying structures for the entire set of technological operations of the mentioned machines is developed. An approach to the simulation of a stress-strain state of an assembled structure of articulation is outlined depending on the type of technological operation performed by the machine. The results of the investigation are implemented at forest machinery enterprises in the Republic of Belarus.
TL;DR: In this article, the results of experimental studies of stress-strain behavior during hardening stages, as well as the stabilization and strength degradation of the rubber-cord casings during the static loading mode have been given.
Abstract: The results of experimental studies of stress–strain behavior during hardening stages, as well as the stabilization and strength degradation of the rubber-cord casings during the static loading mode have been given. The influence of measurements of these characteristics on the drive dynamic loading has been shown. The physical processes of specific friction in the coupling flexible element have been considered. Dependence diagrams of the specific friction on dynamic torque, vibration frequency, torsion angles, and casing temperature have been made.
TL;DR: The results of an experimentally calculated study of low-type hydrodynamic oscillators of the vortex type have been presented in this paper, where the positions of holes that feed the working substance were investigated.
Abstract: The results of an experimentally calculated study of f low-type hydrodynamic oscillators of the vortex type have been presented. The work objective is to research the inf luence of oscillator geometry, in particular the positions of holes that feed the working substance, on the amplitude–frequency responses. These oscillators are applied in wave techniques used in mechanical engineering, the chemical industry, power engineering, oil and gas production, and a number of other industries.
TL;DR: In this article, the thrust sector bearing of a hydrogenerator with oil lubrication is considered and the value of the most important hydrodynamic characteristic of the thrust bearing, which is the lifting force, is defined.
Abstract: The problem solution for the thrust sector bearing of a hydrogenerator with oil lubrication is considered. The value of the most important hydrodynamic characteristic of the thrust bearing, which is the lifting force, is defined. The pressure field is determined by the direct numerical integration of the Navier-Stokes equations for a lubricating oil layer. The case of the absence of heat exchange between the lubrication layer and solid-state components of the thrust bearing and the case when the heat exchange is taken into account are considered. The calculation results, which are compared with an experiment, are presented. The research results can serve as the basis to develop automation systems for designing hydrogenerator thrust bearings.
TL;DR: An enzymatic-cavitation method for the biological treatment of organic-containing wastewater and sludge treatment has been developed, according to which the air supply is carried out not by compressors, but rather ejectors.
Abstract: An enzymatic-cavitation method for the biological treatment of organic-containing wastewater and sludge treatment has been developed, according to which the air supply is carried out not by compressors, but rather ejectors. In addition, low-intensity cavitation is provided. The biological treatment of the wastewater has been performed at a temperature of 10–42°C. The energy consumption of the process is reduced by six times, while the time of sludge treatment is 8–10 h at a pressure of 0.30–0.35 MPa. The treated sludge has some adsorptive properties.