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Abstract: The influence of filling density on the characteristics of a product manufactured by the FDM printing is analyzed. As an object of study, standard samples for testing polymer composites for three-point bending are considered. As a result of experimental studies, the influence of filling density on the rigidity of samples was determined. A variant of gradient filling of the sample material is proposed, which makes it possible to increase the specific rigidity. PubDate: 2024-03-01
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Abstract: The object of the study is a six-component force-measuring device used in test benches of propulsion systems of various designs. In accordance with the State Standards, the methodology of device certification was developed and statistical processing of experimental data was carried out confirmed their reliability. PubDate: 2024-03-01
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Abstract: The paper presents a technology for the out-of-autoclave consolidation of thermoplastic composite material based on the polypropylene and fiberglass. The temperature-time regimes of consolidation and thermoforming were optimized using the differential scanning calorimetry and rheometry methods. A technique for carrying out the vacuum-thermal consolidation and press molding is described making it possible to obtain consolidated plates, which are blanks for thermoforming. PubDate: 2024-03-01
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Abstract: The paper describes in general the approaches to optimizing the technological process of manufacturing the large-sized products made of polymer composite materials by vacuum infusion. In particular, the possibility was considered for optimizing the system of lines for supplying the binder to the preform in the manufacture of single-curvature products. An option was proposed for optimizing the technological process of vacuum infusion based on the porosity criterion. A block diagram of process data was presented. This diagram can be a part of the operation algorithm of the intelligent production equipment, which allows ensuring the optimal technological parameters in real time. PubDate: 2024-03-01
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Abstract: A test bench was developed to study the electromagnetic resistance of technical systems and experimental studies were carried out on the electromagnetic interference induced on a microstrip communication line, when it simultaneously was exposed to several sources of external electromagnetic effects. PubDate: 2024-03-01
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Abstract: The paper investigates the dynamic behavior of an unevenly heated thin-walled parabolic shell of rotation with additional mass under conditions of high-intensity shock wave loading in a gaseous medium. The stress-strain state of the shell resulting from the preliminary uneven heating of its surface is determined from the solution of the equations of thermoelastic equilibrium. The solution to the problem of dynamic behavior of a shell involves integrating the nonlinear motion equations of the shell, as well as the additional mass that is attached to it, under given the initial displacements, initial velocities of zero, and boundary conditions that correspond to the attachment of the shell. PubDate: 2024-03-01
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Abstract: The flutter of a cylindrical shell of finite length, a non-axisymmetric case, is under consideration. A modern algorithm without saturation is presented, specific calculations are considered that have demonstrated its high efficiency. It is demonstrated also that the critical flutter speed has a weak dependence on the number of circumferential waves. PubDate: 2024-03-01
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Abstract: The paper presents an analysis of the influence on the performance of multi-spool axial turbines of aircraft engines of the factors that are traditionally not taken into account when calculating the characteristics using the three-dimensional numerical modeling as well as the mutual influence of spools on each other. By the example of a two-stage cooled turbine of an aircraft engine, the influence of these factors on the efficiency and throughput of the turbine spools was evaluated. An approach to the correction of characteristics to improve their accuracy when transferring them to the thermodynamic model of the engine was taken. PubDate: 2024-03-01
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Abstract: The paper is dedicated to investigating the comparative tribological characteristics of the AlSi10Mg aluminum alloy obtained by the selective laser melting with and without NiP coating on the surface. Studies were conducted under various friction conditions. Research was conducted to assess the possibility of applying the NiP coatings on the surfaces of thin internal channels of parts for aircraft engines and power plants. PubDate: 2024-03-01
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Abstract: The study examines the problem of detecting cracks in gas turbine blades during engine operation. A series of finite element calculations of the destructive pressure in the capsules of the crack detection system were carried out using the example of a turbine blade of the R-2617A profile. The influence of geometric characteristics is analyzed, such as the width of a turbine blade crack opening, the angle of inclination of the crack to the radius, and the crack opening angle, on the pressure value, at which capsules with the active substance are destructed in the system for detecting damage of gas turbine blades. PubDate: 2024-03-01
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Abstract: A numerical model and results of calculations of convective-film cooling of a plate with a double-sided flow around it by high-temperature gas and cooling air are presented. The mathematical model is based on the hybrid 2-D RANS method in a nonstationary formulation for a viscous compressible heat-conducting gas using velocity and thermal wall functions with conjugation of fluid dynamics and heat transfer problems. PubDate: 2024-03-01
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Abstract: The paper considers the optimal control methods of a gyro-stabilized platform stabilization loop in the presence of disturbances with the known power spectral densities or with known bounded L∞-norms. To simplify the practical implementation, the controller order is reduced. Advantages and possible shortcomings of the considered methods are discussed. PubDate: 2024-03-01
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Abstract: An approach to modelling the unsteady axisymmetric vortex flows of a gas-dispersed mixture with an incompressible carrier phase is developed. Numerical modelling of formation of a vortex ring, its capture of dispersed particles and particle transfer is carried out, taking into account the influence of the dispersed phase on the vortex structure of the flow. For numerical simulations, the unsteady Navier–Stokes equations for a viscous incompressible fluid are used. The movement of particles is described based on the discrete-trajectory approach of sample particles. The calculation results make it possible to establish the features of the transfer and behavior of particles of different inertia in vortex rings, as well as changes in the characteristics of the vortex ring in the presence of particles of different sizes and concentrations. PubDate: 2024-03-01
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Abstract: The mechanism of erosive combustion of gunpowder and its consideration in solid propellant rocket engines are analyzed. The issues of the influence of erosive combustion of a solid fuel on changes in the thrust of a jet penetrator engine are considered. A mathematical model is presented for calculating changes in parameters of the intra-chamber process over time, taking into account their changes along the length of the charge for an engine with a freely inserted tubular charge. The obtained calculation results confirm the significant influence of the charge temperature on the intra-ballistic parameters of the penetrator. PubDate: 2024-03-01
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Abstract: On the basis of a hardware-in-the-loop prototype test bench of an integrated diagnostic system for assessing the technical condition of the main functional systems and units of the rotary-wing aircraft, the authors present a promising scheme for the use of artificial neural networks and form a methodological approach to the introduction of neural network technologies to assess the lifetime of each component of the performance monitoring system determining the flight characteristics of the rotorcraft. PubDate: 2024-03-01
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Abstract: The paper presents a technique for determining the area of destruction of sheet materials using the combined deep drawing process. Using a linear diagram of the stress-strain state on the workpiece flange, the critical relative thickness was obtained at the moment, when a cone is formed from a flat workpiece, which makes it possible to determine the area of workpiece destruction at the initial wrinkles. PubDate: 2024-03-01
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Abstract: The paper presents the results of an experimental and numerical study of the operating process of a valveless airbreathing pulsating jet engine. The possibility of boosting the engine by changing the internal aerodynamics and accelerating the combustion process is discussed. The results are compared to the Rayleigh stability theory and an assumption is made about the feasibility of matching the combustion rate with the gas exchange wave process. PubDate: 2024-03-01
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Abstract: A new class of exact solutions of the Navier–Stokes equations was found to describe the multilayer incompressible media with Joule energy dissipation. The velocity field is described by the linear forms with respect to two spatial coordinates (the class of exact solutions of Lin–Sidorov–Aristov). The pressure field and temperature field are quadratic forms with a similar dependence on coordinates and coefficients as in the Lin–Sidorov–Aristov class. PubDate: 2024-03-01
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Abstract: A model is presented for the layer-by-layer finite element stress and strain analysis of sandwich cylindrical shells. The influence of the angular dimension of rectangular cutouts on the stress and strain state of sandwich cylindrical compartments was studied. PubDate: 2024-03-01
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Abstract: The research results are obtained on the basis of a technique implementing the finite element method for solving problems of strength and stability of discrete-reinforced cylindrical shells made of the composite material, taking into account the momentness and nonlinearity of their subcritical stress-strain state. The stability of an anisogrid circular cylindrical shell made of a composite material under pure bending with internal pressure is investigated. We determine the effect of deformation nonlinearity, reinforcing set stiffness, reinforcement layup angles, shell thickness, and internal pressure on the critical loads of the shell instability. PubDate: 2024-03-01
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