


Vol 39, No 9 (2019)
- Year: 2019
- Articles: 23
- URL: https://journal-vniispk.ru/1068-798X/issue/view/14044
Article
Change in Limiting Channel Dimensions during Pneumatic Shaping of Multilayer Structures
Abstract
A mathematical model is developed for determining the inert-gas pressure within rectangular channels in multilayer structures. The model permits calculation of the pressure, stress, and damage in the shaping of materials with different properties. The influence of the relative channel height on the relative limiting rounding radius of a corner element and the membrane thickness and also on the failure time for titanium (VT6S) and aluminum (AMg6) alloys is investigated. The deformation processes are described by the energetic and kinetic theories of creep and damage for viscous flow.



Modal Diagnostics of Lathe Designs with Composite Bases
Abstract
The basic damping properties of composite lathe structures are analyzed by modal diagnostics. New experimental results and literature data from non-Russian research are employed. The damping properties of cast-iron and composite lathe structures are compared. The composites considered are ferrocement, polymer concrete, and metal concrete.



Influence of Input Acceleration of Broad-Band Random Vibrations on the Amplitude–Frequency Characteristics of Hydraulic Bearings
Abstract






Influence of the Properties of Machining Fluids on the Frictional Coefficient in Alloy Turning
Abstract
Abstract—In the cutting of four different alloys, the effectiveness of two machining fluids is investigated as a function of their composition and physical properties. An index characterizing the influence of each chemical element in the fluid on its effectiveness is proposed.



Production of Large Disks from Cylindrical Blanks by Plastic Deformation. 4. Deformation of a Protrusion by an Annular Punch
Abstract
The deformation of a protrusion by a peripheral annular punch is mathematically described. The protrusion is formed as a result of central-punch introduction in the manufacture of large disks or hard-to-deform disks by plastic deformation. The maximum force at the end of deformation is found. The relative radius of the annular punch ensuring equal stamping forces for the central and annular punches is determined.



Pore Formation in the Laminar Structure of Wear-Resistant Modified Powder Coatings
Abstract
The open porosity of wear-resistant modified coatings is investigated, and their macrostructure is analyzed. A statistical method is proposed for describing the formation of porosity in the laminar structure of a powder coating. The matrix of transition probabilities is determined for a uniform Markov chain. The porosity of a coating on a smooth substrate is calculated.



Surface Microhardness of Parts Machined by Asymmetric Uninterrupted Lapping
Abstract
To improve the wear resistance of high-precision machine parts, a new technology has been developed: asymmetric uninterrupted lapping. The influence of its basic parameters on the surface microhardness is investigated. The optimal parameter values corresponding to maximum surface microhardness are determined.



Selection of a Cutting Tool by Means of a Digital Model
Abstract



Current Regulation in Contact Welding
Abstract
Algorithms for current stabilization in the control of contact welding are considered. The proposed method for specifying and maintaining the welding current permits correction of the thyristor firing angle by means of an approximate formula taking account of the measured current-pulse parameters in phase regulation. The proposed method simplifies the equipment and increases the efficiency of regulation.






Energy-Efficient Actuator for the Control System of Promising Vehicles
Abstract



Verification of Feasibility Studies at High-Technology Enterprises
Abstract
Innovation and investment in the development of high-technology enterprises must be preceded by thorough feasibility studies. The potential errors in the associated management decisions may be categorized. In the light of such potential errors, feasibility studies must be verified by qualified and impartial experts, with a final verdict regarding the presence or absence of significant errors and perhaps recommendations for improvement. In the present work, the most common approaches to expert verification are categorized, and proposals are made regarding the development and synergetic combination of such methods.



Mutual Influence of Capillary Pumps in Heat-Pipe Systems with Different Evaporator Loads
Abstract
Thermal management systems that are not hermetically sealed have been developed for use in spacecraft; in such systems, scientific equipment and instruments operate in open space. Accordingly, new methods of thermal regulation have been developed: axial and loop heat pipes; and honeycomb thermal panels with embedded axial heat pipes. Heat transfer in heating systems with heat pipes is based on evaporation and condensation in a two-phase loop. The working fluid moves under the action mainly of capillary forces that appear in capillary channels or honeycomb structures for axial heat pipes and in the porous heated medium (capillary pump) of the loop heat pipes.



Manufacture of the Transceiver Housing for an Active Phased Array Antenna with Built-In Cooling Channels by Selective Laser Melting
Abstract
A cooled transceiver housing of an active phased array antenna is produced by 3D printing from aluminum, on the basis of selective laser melting (SLM). The housing walls contain cooling channels, whose geometry ensures effective heat transfer from the active electronic components of the transceiver and also permits the manufacture of high-quality samples on existing 3D printing systems and facilitates cleaning of the channels after printing. The housing is made of AlSi10Mg aluminum, with an acceptable content of closed pores (no more than 1%). Its physicomechanical properties correspond to those of regular aluminum alloys used in the traditional manufacturing technology for such components. This housing may be used in advanced radar systems. The research permits recommendations for further development of the technology.



Preliminary Geometric Verification of the Electronic Model in Additive Manufacturing
Abstract



Stability of Panels of a Thermoelastic Shell Heated at the Edge by a Mobile Point Source
Abstract
The thermostability of thin-walled structures is considered by means of a thermoelasticity problem in a three-dimensional quasi-static formulation. Finite-element models of panels in the form of a circular cylinder and a plate reinforced by ribs are constructed. Numerical solutions are obtained for the stability loss of thermoelastic thin-walled reinforced structures with intense edge heating by a mobile heat source.






Composite Heat Shields in Intense Energy Fluxes with Diffusion
Abstract
A method is proposed for bench testing of reusable composite samples under intense thermal and ionizing radiation. Tests are conducted under intense energy fluxes. As a result of the tests, the temperature field and the displacement field at the surface of heat-shielding composite and in its depth are determined at different times. The proposed mathematical model adequately determines describes the temperature distribution in the composite shield under the action of intense energy and radiation fluxes. The influence of diffusion and the temperature field on the displacement field in the composite is studied. The theoretical results are compared with experimental data.



High-Temperature Protective Coatings on Carbon Composites
Abstract



Ultrasonic Application of Nanostructured Coatings on Metals
Abstract
A method is developed for applying metallic, intermetallic, or ceramic coatings to a metal surface by means of ultrasound (high-frequency acoustic vibrations). The method may also be used to reinforce metallic surfaces by means of particles of another metal or ceramic. Under the action of ultrasound, chemical reactions and solid-phase diffusion are accelerated. That is accompanied by strong adhesion of the metal matrix to the particles; solid-phase transformations; and the formation of intermetallides, oxides, carbides, nitrides, and other compounds, depending on the surrounding gas and the powder composition. As a result, a composite coating or layer with nanostructure or microstructure is formed on the surface.



Creating an Atmosphere within Spacecraft
Abstract
In space flight, the creation of an artificial atmosphere for those on board represents a serious challenge. New approaches produce environmentally and physiologically satisfactory conditions for prolonged human residence and optimize the heat and mass transfer in the spacecraft. That reduces the impact of space flight on human passengers and thereby minimizes health hazards. This is especially important in regard to plans for piloted flights to other planets, in the light of their duration and the demands placed on those on board.



Environmental Impact of Paints in High-Tech Production
Abstract
Assessment of the environmental impact of paints and varnishes is based on life-cycle analysis. A method is outlined for calculating the index and coefficients of environmental safety of the paints. Such assessments not only permit optimization of the paint composition in environmental terms but also selection of the safest coating from those available.


