Vol 20, No 6 (2018)

The article discusses approaches to optimizing the organizational structure of the technological service to improve the effectiveness of the processes of the quality management system; proposed approaches to the analysis of the functions (operations) performed by technologists; describes the method of redistribution and valuation of functions to determine the required number of technologists.

The article describes the results of analysis models of planning and preproduction of additive manufacturing by determining the optimal SLM technological parameters that provide the required quality, surface properties and dimensional accuracy, the minimum production cost.

The paper presents the results of an analysis of the effectiveness of the implementation of a two-circuit active control system and the early detection of a “special” cause of variability in mechanical processing operations.

Article describes the adoption of the Taguchi method in selective laser melting process of sector of combustion chamber by numerical and natural experiments for achieving minimum temperature deformation. The aim was to produce a quality part with minimum amount of numeric experiments. For the study, the following optimization parameters (independent factors) were chosen: the laser beam power and velocity; two factors for compensating the effect of the residual thermal stresses: the scale factor of the preliminary correction of the part geometry and the number of additional reinforcing elements. We used an orthogonal plan of 9 experiments with a factor variation at three levels (L9). As quality criterias, the values of distortions for 9 zones of the combustion chamber and the maximum strength of the material of the chamber were chosen. Since the quality parameters are multidirectional, a grey relational analysis was used to solve the optimization problem for multiple quality parameters. As a result, according to the parameters obtained, the combustion chamber segments of the gas turbine engine were manufactured

In the article the model to generate the level of outstanding orders. The model takes into account the values of the velocities of the incoming stream of orders of magnitude speed outbound shipment of products. This model is implemented using Matlab software package using Simulink dynamic system modeling tools.

The research of the open porosity of the wearproof modified coverings depending on composition of powder materials and the technological modes of drawing is. The method of hydrostatic weighing has determined levels of open porosity of gas-thermal coatings with the modifying additives, the interrelation of open porosity with roughness of surfaces of wearproof coatings is established.

Method of combined deformational processing of carbon steel wire is presented in the paper. The essence of the method consists in applying on the continuously moving wire the deformation of tension and compression at drawing, bending and torsion kinds of deformation when passing the four-rolls system. Advantages of the method consist in using tools of metal ware manufacturing and simplicity of the equipment. The scheme of the laboratory setup which makes it possible to apply on the wire different kinds of plastic deformation (tension, compression, alternate bending, torsion) is presented. Pearlite carbon steel wire with 0.5 %C was chosen as an object for investigation as the in-demand metal product. Modes of the carbon steel wire combined deformational processing are presented. The effect of deformational processing on texture, mechanical properties and residual stresses in carbon steel wire with 0.5% C was found studied experimentally. Texture and residual stresses were investigated by X-ray analysis using Кα - radiation of chromium anode of SHIMADZU XRD-7000 diffractometer. The accuracy of residual stresses and texture measurement during X-ray analysis was improved by special sample preparation when pieces of the carbon steel wire after deformational processing were tightly pressed in the special polymer. The axial texture was investigated by diffractometer I(α) curves. Residual stresses were estimated along the (211) line of α-phase (double diffraction angle 2θ ≈ 156°). It was shown that crystallographic texture after all kinds of deformational processing by drawing, alternate bending and torsion and their combination became doublecomponent: <110> + <111>. This promotes the increase of carbon steel wire strength and ductile properties after combined deformational processing and proves the high importance of texture in ensuring the mechanical properties level. The obtained experimental results showed that the method of combined deformational processing by drawing with alternate bending and torsion has significant advantage as compared with industrial technology of carbon steel wire manufacturing due to possibility to improve its mechanical properties in a wide range.

A method for determining the hypersonic airplane pressurized compartment thermal state is developed based on the use of a mathematical model of the compartment with metal honeycomb constructions thermal state. The mathematical model of the system of the pressurized thermal-insulated compartment with a surface cooling system is represented by a system of differential and algebraic equations describing the convective and radiation heat transfer of the skin outer surface, convective heat transfer in the cooling system channel, and heat exchange by direct conduction of the honeycomb structure. The development of a stochastic method for solving the direct heat exchange problem of a metal honeycomb construction using stochastic differential equations by the Euler method and random walk by spheres method is carried out. The random process trajectories simulation was carried out using the parallel sensor of Gaussian random variables from the Intel MKL library. To solve the stiff set of ordinary differential equations the implicit Rosenbrock method of second-order is used. The inverse problem for the metal honeycomb construction is solved by a stochastic quasigradient algorithm with a variable metric. In addition, parametric identification of the compartments thermal state model is proposed to be carried out by the composition of the steepest descent method, Newton’s method and the quasi-Newton method of Broyden-Fletcher-Goldfarb-Shanno. The product vector of estimated coefficients errors of a nonlinear mathematical model is determined by the expression that is a quantile function χ2 - distributions and the Gram matrix. At the same time, the method of joint confidence evaluation region projection on the coordinate axes of the coefficients space is used. Investigations of the hypersonic aircraft were conducted in accordance with the Airworthiness standards. The required thickness of the metal honeycomb construction of the pressurized compartment, the temperature and the refrigerant consumption of the hypersonic airplane surface cooling system are obtained. Optimization of the metal honeycomb structure of the hypersonic aircraft pressurized compartment and the surface cooling system was carried out to ensure the reliability of the aircraft and its on-board equipment operation, comfortable conditions in the cockpit and passenger cabin.

The article is devoted to the design and research of the thermal state of the recuperative exchanger. The results of calculations of convergence of thermal balance, graphic dependences of consumables and thermal characteristics of the objects of research.

The article is devoted to the creation of an auxiliary power plant for the implementation of the concept of an “electric aircraft”. A number of promising projects of aircraft, from a number of so-called “more electric aircraft”, presuppose the regular operation of an auxiliary power plant (APU) throughout the entire flight to generate electricity. It is assumed that the autonomous operation of the APU at the nominal mode during the whole flight is more energetically more favorable than the selection of the mechanical power from the engines with the subsequent transformation into electric power. Further realization of the concept of an “electric aircraft”, associated with the increase in energy consumption on board even with simultaneous increase in the energy efficiency of electromechanisms and other consumers, will lead to an increase in the unitary equivalent (total for electricity and air) of APU power. Another problem is related to the fact that the long-term requirements for civil and military aircraft require the search for ways to significantly increase the fuel efficiency of the aircraft as a whole. One of the main reserves to achieve these goals is a comprehensive increase in the efficiency of the propulsion system and APU as a source of secondary heterogeneous power for the aircraft users. At the present time, in the world aircraft industry, constructive solutions for the schematic redistribution of consumption and power generation are tested through the transition to electric power mechanisms and the generation of electricity in auxiliary installations. Fuel cells are considered as one of the main means of further improving the economy and improving the environmental performance of prospective aviation APUs. The basis of all circuit solutions for aviation hybrid APUs is a combination of a fuel cell (FC) battery and a turbocharger group that provides the necessary level of parameters of working bodies with respect to pressure and temperature required for the efficient operation of fuel cells. The weight of the design of the advanced aviation APU being created should not be greater than the mass of the APU structure, compared to the base one for the gas turbine aviation APU. The paper presents a methodology for estimating the main energy and mass-dimension characteristics of a power plant for conducting a comparative analysis of variants of hybrid auxiliary power plants with fuel cells for prospective civil aviation aircraft.

The article presents the results of studies of the dynamic characteristics of acoustic dampers of oscillations of the liquid at the longitudinal distribution of parameters. It is shown that to improve the characteristics of dampers it is advisable to make them multi-section.

The article describes the results of multi-criteria optimization of a three-stage axial uncooled low-pressure turbine. The purpose of optimization was to improve the turbine operating process according to three criteria: the angle of flow at the turbine output, the value of the residual twist of the flow at the turbine output, the value of the turbine efficiency. To solve the problem, complete re-profiling of all turbine blades was performed. Re-profiling included changing both the shape of the blade sections and the relative position of the sections relative to each other in the radial direction (3D profiling).

The article indicates the sources of possible energy risks and ways to eliminate them. The necessary elements for building a system for managing energy costs have been proposed and described. Recommendations for the most rational use of energy management tools are proposed. The conclusions about the requirements and the need to develop and implement energy policy in the enterprise are given.

The article is devoted to the development of theoretical justification and practical implementation of the acoustic method of control of geometrical parameters of pipes as the main object of pipeline transport used in systems of production, transport and consumption of thermal energy. The method is based on the mathematical processing of the acoustic signal reflected from the open end of the pipe and allows to obtain information simultaneously about the length, diameter of the pipe with quality control of the inner cavity. The proposed algorithm for measuring the diameter extends the functionality of the measuring equipment and allows you to automatically calculate the phase shift of the acoustic signal when reflected from the open end of the pipe, thus fully automates the process of measuring the length of pipes of arbitrary diameter. Experimental studies carried out using the developed algorithm have shown that the relative error in measuring the length of the pipe length of 3 m was not more than 0.15%, the error in measuring the diameter of the pipe equal to 110 mm was not more than 7%.

A method for ensuring the survivability of an attitude control system for a land-survey satellite and algorithms for digital control of a minimally redundant cluster of the rotor drives and magnetic actuator at the faults of any reaction wheels are presented.

Algorithms for control of a space robot-manipulator during its approaching and mechanical capturing a passive satellite in the conditions of uncertainty and incompleteness of measurement are presented, results of computer simulation are given.

The article is devoted to the management system optimization of the training facilities of workshops maintenance. The purpose of the research is to study the behavior of complex objects, such as training tools and their management systems, to develop the mathematical model of the management system of training tools, oriented to the framework of simulation models usage. The authors have developed the mathematical model describing the process of performing the operation by the trainee, with the functioning of the training tool of the maintenance workshop, the application of which would allow the implementation of modern approaches in the control systems for such type of simulators. The system of linear equations with variable coefficients is presented in the article, which is the basis for developing the simulation model that is programmable in the MATLAB / Simulink and which would allow analyzing the system conduction taking into account the factors influencing the simulated system and with the purpose of further optimizing the design solutions. As a result, the application of modern approaches, in particular optimization, to the design of the management system of the training and training facility of the maintenance workshop helps to improve the rates of mastering military equipment.