Vol 17, No 2 (2018)

Full Issue

AIRCRAFT AND SPACE ROCKET ENGINEERING
Backstepping synthesis of the height control system of an unmanned aerial vehicle
Akhramovich S.A., Barinov A.V., Malyshev V.V., Starkov A.V.
Abstract

Synthesis of the height control system for an unmanned aerial vehicle (UAV) with a soft wing, like a paraglider or a powered parachute, is considered in the article. An UAV is described, its scheme is shown, the forces and moments acting on it in the longitudinal plane are examined. A mathematical model of UAV motion is described in a body-axis coordinate system. Direct control is provided by the thrust motor. The thrust motor is mounted on the UAV so that the thrust is directed along the OX axis in the OXY plane. It is proposed to form the height control law on the basis of the thrust moment, which gives the advantage of stabilizing the angular velocity and the pitch angle. To synthesize the control and stabilization systems, the backstepping method is applied. According to this method, the task of developing a control law for the entire system is divided into a sequence of respective subtasks to lower-order subsystems. The algorithm of backstepping consists in making each integrator of the object stable by adding the feedback computed from this algorithm. The resulting control takes into account the nonlinearity of the object and depends on the entire state vector. The main advantages of the regulator obtained are: the system is stable within a broad range of input values; by varying the regulator coefficients, you can easily select the desired characteristics of control quality. The results of numerical simulation of UAV motion with the regulator obtained in the MATLAB environment are presented in the article.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):7-22
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Optimization of space vehicle combined orbital plane change maneuver on the basis of the successive linearization method
Balakin V.L., Ishkov S.A., Khramov A.A.
Abstract

The task of optimizing the space vehicle combined orbital plane change maneuver with the aim of maximizing its final mass is considered in the paper. Burst of power is used for the vehicle’s exit from the initial low earth orbit and subsequent re-entry. Starting from atmospheric entry till the end of the orbital plane change with the entry in the final orbit the angle of attack, the air-path bank angle and the fuel-flow rate are used as controls. Limitations for the angle of attack, fuel-flow rate, adiabatic recovery temperature, longitudinal and vertical load factor are introduced. The successive linearization method is used to determine the optimal control programs. Solving the optimization task is exemplified by a hypothetical space vehicle. The results of modeling space vehicle motion are presented. The changes in the determined “aerodynamic” (angle of attack and air-path bank angle) and “motion” (fuel-flow rate) controls with increasing the angle of orbital plane change are discussed with and without account of the key limitation on the modes of motion – maximum adiabatic recovery heating temperature.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):23-36
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Forecasting low-cycle fatigue life of gas-turbine engine parts by the method of equivalent tests for specimens with stress concentrator under extension-compression
Bukatyy S.A., Pakhomenkov A.V., Solntsev G.A., Bukatyy A.S.
Abstract

A method of low-cycle fatigue equivalent tests based on the application of test specimens whose stress-strain state shall be similar to the stress-strain state of the part to be investigated is proposed in the paper. The stiffness ratio of the stressed state is used as the similarity criterion of stress and strain state of the specimens and the part. The method was successfully applied on the low-pressure compressor disk of a gas turbine engine. Specimens with a circular cross section and a V-concentrator were used as equivalent specimens. The tests were carried out as follows: the specimens were tested under stretching and compression for the zero-to-compression stress cycle; the disks were tested on a dedicated test bench with the spin-up of up to 5000 rpm. The proposed method of equivalent tests makes it possible to forecast low-cycle fatigue life of large-sized critical parts whose full-scale tests cannot be carried out. The method can also be used to assess the high-cycle fatigue life of parts and to forecast their long-term strength. The obtained equations make it possible to design and optimize the construction of aviation parts: the permissible value of strain rate in the most strained area of the part can be determined by the specified fatigue life.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):37-46
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Accuracy of autonomous navigation by the mutual method in the case of a group flight of space vehicles
Golyakov A.D., Richnyak A.M.
Abstract

The article presents the results of an investigation of the accuracy of estimating errors in the determination of the motion parameters of the center of mass of a small spacecraft performing a group flight together with other small spacecraft, among which there is a small spacecraft that acts as the leader of the group.  The angles between the directions to the small spacecraft-leader, and navigational stars, one of which is in the plane of the orbit of the small spacecraft, and the direction to the second one coincides with the binormal of this plane are chosen as the primary navigation parameters measured by the onboard facilities of the small spacecraft. When estimating the errors in determining the parameters of the motion of the center of mass of a small spacecraft, assumptions are made about the central gravitational field of the Earth, the normal law of error distribution of on-board navigation measurements with known constant variances. The research was carried out on the basis of the method of analytical estimation of the accuracy of autonomous navigation of space vehicles. As a result of the studies, analytical expressions of covariance matrices are obtained that allow one to estimate the maximum achievable accuracy of the solution of the problem posed, depending on the altitude of the orbit of a group of small space vehicles, the displacement of the slave small spacecraft relative to the small spacecraft-leader by the latitude argument, the variances of measurement errors and the number of measurements during a navigation mode. The presented results can find application when it is necessary to substantiate ways of improving the accuracy of autonomous navigation of small spacecraft performing group flights.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):47-57
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Assuring performance characteristics of gas-turbine engine parts and assemblies using electrospark doping
Denisov L.V., Boytsov A.G., Siluyanova M.V.
Abstract

The article describes surface hardening of aircraft engine titanium-alloy hydraulic cylinder face using the method of electro-spark doping by low-energy discharges. Graphite electrodes were used to provide functional behavior of the cylinder surface layer. The carbon oxide layer formed has a highly dispersed structure of a complex composition (with particles of titanium carbide, titanium oxide, graphite), 3-10 micron thick, characterized by high hardness and sliding properties. Graphite electrode alloying practically does not change the part dimensions. Subsequent diamond burnishing of the hardened surfaces decreases the value of the friction coefficient and surface roughness. Healing of defects and micro-cracks improves the fatigue resistance of the part. The developed technology makes it possible to assure the characteristics required of hydraulic cylinder work surfaces and increase their life.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):58-67
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Computational investigation of aerodynamic and acoustic characteristics of an ultrahigh-bypass ratio counter-rotating fan
Druzhinin Y.M., Mileshin V.I., Rossikhin A.A.
Abstract

A computational investigation of aerodynamic characteristics of a model ultrahigh-bypass ratio counter-rotating fan (= 20) developed at CIAM within the framework of the European Project COBRA (Innovative Counter Rotating Fan System for High Bypass Ratio Aircraft Engine), is presented in the work. The unsteady nature of the flow in a counter-rotating fan was studied; the rotor-rotor interaction intensity and unsteady viscous wake propagation through the axial gap and second rotor blade were analyzed. The results of numerical investigation of the fan tonal noise in the approach mode are also presented. The acoustic calculations were performed using the in-house CIAM code 3DAS. Far-field directivity diagrams for the first 16 harmonics of tonal noise in the front and rear hemisphere, obtained in the calculation, are shown. The results were compared with the respective results of calculation for a model high-bypass ratio counter-rotating fan with a high-bypass ratio = 10 (designed in VITAL project). Additionally the results were compared with the experimental results for a fan with = 20.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):68-79
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Biological module “BiNOM” for cubesats of the SamSat family
Zakharov V.P., Konyukhov V.N., Bakhtinov P.I., Molchkov E.V., Kornilin D.V., Konovalov S.G.
Abstract

The biological module BINOM is a platform for multi-purpose biomedical space experiments with a wide range of biological objects (bacteria, algae, fungi, plants, multicomponent ecosystems). It was designed as a payload for SamSat nanosatellites and can be easily mounted on any other space vehicle. The module consists of three main blocks – a sealed chamber for biological objects, a life support system, a system of control and measurement supporting scientific data acquisition and pre-processing. The BiNOM interacts with the electronic systems of the nanosatellite with the help of a single four-pin connector. The life support system maintains the required temperature, pressure, humidity and gas mixture composition in the chamber of the biological object. The control system makes it possible to carry out biomedical experiments in the automatic mode according to a specified program or by commands from the ground control post. The control system is designed to measure the parameters of the environment and the biological object. The module supports visualization of objects in the UV-VIS-IR spectral range, fluorescence analysis, temperature and humidity measurement at several points, pressure, concentration of oxygen and carbon dioxide. Additional sensors can be used depending on the goals of the experiment. A module prototype was made and a number of tests were carried out to confirm the adequacy of the engineering solutions proposed. In particular, the vacuum chamber tests showed that the pressure loss in the pressure hull does not exceed 20% per year. A number of biological experiments demonstrated the possibility of initialization, growth and life support of various biological objects during a long, up to two months, period.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):80-90
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Problematic issues of assessing the strength of axisymmetric parachute systems by conducting breakdown tests in flight experiments
Ivanov P.I., Kurinnyy S.M., Krivorotov M.M., Shmerova G.V.
Abstract

The article deals with problematic issues of assessing the strength of axisymmetric parachute systems in flight tests. One of the main tasks in preparing for flight tests is the choice of conditions for carrying out an experiment. Variants of parachute system breakdown tests are considered. Loads occurring in parachute system inflation are analyzed. The specific character and peculiarities of parachute damages and failures are presented in the article. The problem of parachute system destruction under breaking loads considerably smaller than the parachute load bearing capacity is posed. We propose to use methods of experimental optimization and stochastic approximation to reduce the number of experiments. The conclusion is drawn on possible ways of solving the problem of assessing the breaking load and load bearing capacity obtained in assessing the strength of parachute systems in a flight experiment.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):91-99
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Modal analysis of the dynamic mockup of “AIST–2D” small spacecraft
Igolkin A.A., Safin A.I., Filipov A.G.
Abstract

The article describes a methodology of experimental determination of dynamic behavior of rocket and space equipment, using the example of AIST-2D small spacecraft. Experimentally obtained modal characteristics (natural modes and frequencies) are compared with modal characteristics calculated for the said spacecraft using a finite element model (FEM). The natural modes and frequencies of the spacecraft were experimentally obtained using scanning laser vibrometry; the modal analysis was performed using finite elements and the MSC. Patran / Nastran FEM package. The objectives and tasks are formulated; the main stages of modal analysis are described. It is necessary to update the finite-element models of spacecraft parts to obtain precise loads applied to such parts. During the tests target resonance frequencies of the test object were obtained for the 5-130 Hz range, as this range contains the first modes of the structure. Since the spacecraft is characterized by many uncertainties in stiffness parameters, the error of determining own frequencies was as high as 45.75% at the first stage of the research, which confirms the necessity of carrying out modal analysis. Dynamic characteristics of spacecraft structural elements obtained during the research will allow creating more precise and reliable spacecraft dynamic models at the design stage; this, in its turn, will improve precision of load calculations and reliability of the spacecraft in general.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):100-108
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Determination of large-size liner impedance based on numerical simulation of sound propagation in a duct with specified azimuthal modal structure
Korin I.A., Palchikovskiy V.V., Pavlogradskiy V.V.
Abstract

A study of determining impedance of a large-size sound-absorbing liner with azimuthal acoustic modes propagating in a duct was conducted on the basis of numerical simulation. The first stage of the study consisted in developing a method of impedance eduction on the basis of a simple cylinder model with microphones installed outside the sound-absorbing liner section. The full-scale experiment was replaced by numerical simulation of the propagation of a specified azimuthal noise structure in a cylindrical duct with known impedance wall (direct problem). As a result of solving the direct problem, the values of acoustic pressures are determined at those points where microphones are to be installed during the realization of the full-scale experiment. The results obtained are used to find the initial impedance value (inverse problem). The solution of the inverse problem using the procedure of minimizing the discrepancy between the acoustic pressures of the direct and inverse problems showed good accuracy of finding the impedance. It was also found that the accuracy of impedance eduction practically does not vary with the angle of installation of the linear array of microphones. The second stage of the study consisted in applying the developed approach to the model of a facility for testing large-size sound-absorbing liners. Acceptable accuracy of determining the impedance was achieved with certain quality of the finite element mesh. It has also been checked that, to save the computational time, for some acoustical modes acceptable accuracy of impedance eduction is possible in an axisymmetric statement. Thus, the possibility of using the proposed approach based on numerical simulation for the eduction of  sound-absorbing liner impedance was confirmed.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):109-121
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Improvement of friction units of power plants by aplying ceramic composite spray coatings
Siluyanova M.V., Fertikov A.O.
Abstract

Modifying the working surface of a product by applying protective and functional coatings makes possible considerable changes in the mechanical, optical, electrical, magnetic, thermal and chemical properties of the original structural material, its real surface, producing articles with protective, for example, anti-corrosion, wear-resistant and other properties. We investigated the possibility of improving the friction units of aircraft power plants by applying nanostructured ceramic composite spray coatings. A heavily loaded bearing forming a part of the gearbox of a turbojet engine is used as a prototype of the friction unit. The advantages and drawbacks of improved friction units as compared to production models and their prototypes made according to an improved technology are assessed. The results obtained during the experimental work are presented. A positive conclusion is made about the use of nanostructured composite materials in the development of friction units; the most favorable method of coating is determined.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):122-131
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MECHANICAL ENGINEERING
Development and research of a device for gas sheet stamping with a piston pressure multiplier
Botashev A.Y., Bayramukov R.A.
Abstract

Traditionally, sheet stamping is carried out in the cold state of the workpiece being processed. At the same time, due to the limited plasticity of the workpiece, stamping parts of complex shape is performed in several operating steps, which significantly increases the cost of production. The article is devoted to the development and research of a device providing stamping of parts with heating of the workpiece being processed. The device comprises a die and a working cylinder between which  the workpiece is placed, as well as a combustion chamber separated from the working cylinder by a piston. The heating of the sheet billet and its punching is carried out in two stages within 1...2 s with its exposure to the action of gas mixture combustion products. At the first stage, the billet is heated and deformed by the combustion products formed in the die cavity and the working cylinder, whereas at the second stage these processes take place due to the energy of the combustion products formed in the combustion chamber. The workflow of the developed device was studied. The regularities of the pressure and temperature changes of the gas that heats and deforms the billet being stamped were established. The optimum proportions of the volumes of the combustion chamber and the working cylinder were determined. The developed device ensures stamping of complex-shaped parts in one process step due to the heating of the workpiece. In this device the pressure on the surface of the workpiece being processed is 2...3 times higher compared with the existing analogues, which ensures stamping of heavy-thickness parts, as well as parts made of hard-to-deform alloys.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):132-143
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Prediction of endurance limit of hardened parts with account of operational factors
Pavlov V.F., Kirpichev V.A., Kiselev P.E., Shvetsova A.A.
Abstract

Fracture endurance limit is one of the main parameters used in calculating the strength of surface hardened parts.  The influence of various operational factors along with hardening should be taken into account in predicting this parameter. Prediction of the endurance limit under stress concentration was carried out according to the criterion that takes into account the influence of residual stresses on the surface of the dangerous section of a hardened part, as well as the criterion of the average integral residual stresses over the thickness of the hardened surface layer equal to the critical depth of a non-propagating fatigue crack. The effect of surface hardening on the endurance limit was analyzed taking into account such operational factors as the type of deformation, working temperature, the asymmetry of the loading cycle of specimens made of steels and aluminum alloys. Fatigue tests of cylindrical specimens with circular notches of a semicircular profile were carried out under torsion, bending and tension-and-compression. It was established that the use of the criterion of the average integral residual stresses is quite a good indicator of the effect of surface hardening on the fracture endurance limit taking into account the operational factors studied.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):144-153
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Comparison of heat generation estimation methods for angular contact ball bearings
Petrov N.I., Lavrentyev Y.L.
Abstract

The article reviews domestic and foreign methods of estimating heat generation in angular contact ball bearings. Models for general-purpose bearings and for aviation angular contact ball bearings are considered. Models adopted at bearing manufacturers FAG (Germany) and SKF (Sweden) are considered for general-purpose bearings. Models developed at the KAI, CIAM named after P.I. Baranov and MTU (Germany) are considered for aviation bearings. The results of heat generation obtained in testing bearings 126206 (30×62×16 mm) and 176126 (130×200×33 mm) are presented. The calculated heat generation values, obtained by various methods, are compared with the experimental data. On the basis of the research the models that yield the calculated values of heat generation in ball bearings closest to the experimental data are specified. They can be used to estimate heat generation in aviation roller bearings with oil jet lubrication.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):154-163
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Evaluating the efficiency of hardening treatment of cylindrical parts made of structural steels
Sazanov V.P., Pavlov V.F., Semyonova O.Y., Prokhorov A.A.
Abstract

The investigated objects are solid and hollow notched cylindrical specimens made of structural steels surface-hardened with the use of two techniques: hydraulic shot blasting and air shot blasting. The subject of the investigation is the residual stresses in the surface layer of the specimens after hardening. The purpose of the work is to investigate the influence of residual stresses on high-cycle fatigue and to establish the possibility of using the developed calculation methods for the evaluation of surface hardening efficiency. Residual stress distribution in the surface layer and high-cycle fatigue resistance of cylindrical specimens were analyzed using calculation and experimental methods. The use of calculation methods for evaluating the efficiency of hardening treatment showed that the difference between the calculated  and experimental values of the endurance limit increments due to hardening of cylindrical specimens with semicircular notches does not exceed 8% in the case of hydraulic shot blasting (steel 40X) and 11% in the case of air shot blasting (steel 20). The use of calculation methods for defining the endurance limit increment makes it possible to evaluate the efficiency of surface hardening with practical accuracy without long- run and expensive fatigue tests.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):164-173
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Heating and melting of bulk lump materials
Fedyaev V.L., Osipov P.P., Belyaev A.V., Sirotkina L.V.
Abstract

Porous materials, including bulk materials, are widely used for cleaning liquid and gaseous media from mechanical impurities, as heat insulating materials, working bodies in various technologies of mechanical engineering, power engineering, metallurgy, chemistry, petroleum chemistry, food industry, pharmacology, etc. The aim of the work is mathematical modeling of heat transfer in disperse bulk media, their melting, engineering assessment of a number of indicators essential in practice. A bulk disperse medium consisting of solid particles (lumps) of different shapes, sizes and composition, randomly arranged relative to each other, is considered. The article provides relationships for determining effective density, heat capacity, thermal conductivity, taking into account radiant heat transfer between particles (lumps) as applied to porous bulk materials. Using the obtained relationships, the model problem of heating and subsequent melting of the disperse medium under consideration is solved. The melting rate and the relaxation time during which the system consisting of melt and lumps comes to thermodynamic equilibrium are assessed. Though only one-dimensional thermal processes are considered in this paper, the proposed approach can be extended to two- and three-dimensional cases and applied for mathematical description of thermal behavior of nonmetallic porous materials. It is these materials that are mainly used for thermal insulation. Their behavior, especially in extreme, abnormal conditions is of great interest.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):174-182
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INFORMATION SCIENCE, COMPUTING TECHNOLOGY AND CONTROL
Development of a multiuser system web-interface as a tool of using mathematical packages for solving engineering tasks
Danilenko A.N., Zhdanov I.A.
Abstract

Creating web-applications is illustrated by an example of developing a multiuser web-interface for the computer-aided search of solving systems of non-linear equations in the Django package. The automated system is implemented in the Python programming language. Creation of a web application is proposed based on the client-server technology, where the client part implements the user interface, forms requests to the server and processes the responses from it. The server part receives the request from the client, performs the necessary calculations, then forms a web page and sends it to the client online. The developed application is designed for solving systems of nonlinear equations. The system has the ability to solve systems of equations of any dimensionality, save the solutions on the server and the PC, and to visualize the step-by-step process of solving and plotting. The system efficiency was tested on real data. For example, gas turbine engine parameters were calculated and the obtained results were used to design a 3D model of a gas turbine engine

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2018;17(2):183-190
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