The Control and Data-Acquisition System of the СПРУТ-VI Instrument Package

The control and data-acquisition system of the -VI instrument package mounted on board the Mir space station in 1999 is described. The system was based on two onboard microcomputers installed both inside and outside a pressurized compartment. The system unified the operation of various sets of equipment (radiation monitoring, radiometric, wave, materials science, and magnetic) and allowed the transfer of large data arrays from detectors located on the outer surface of the station. It was possible to reprogram the entire system under space flight conditions. An off-line data-recording unit, which was later brought back to Earth, was used.     

The Mathematical Simulation and Study of the Electrical Resistance of the Friction Zone of the Hip Joint Endoprosthesis with a Metal–Metal Friction Pair

The paper has described a model of the static load on the hip joint that takes into account the anthropological parameters and a mathematical model of the change in the resistance of the endoprosthesis under the influence of an external load at different rotation angles of the cup component. The theoretical studies have revealed the character of the changes and assessed the possible ranges of variations in the diagnostic parameter that are required to develop diagnostic equipment and methods for testing and interpreting diagnostic information during the tribotesting of individual types of implants.     

Surface roughness prediction for the milling of Ti–6Al–4V ELI alloy with the use of statistical and soft computing techniques

This study focuses on Ti–6Al–4V ELI titanium alloy machining by means of plain peripheral down milling process and subsequent modeling of this process, in order to predict surface quality of the workpiece and identify optimal cutting parameters, that lead to minimum surface roughness. For the purpose of accomplishing this task a set of experiments were performed on a CNC milling centre and design of experiments based on Box Behnken Design (BBD) for a three factor and three level central composite design concept was conducted. Depth of cut, cutting speed and feed rate were selected as input parameters and surface roughness was measured after each experiment performed. At first, Response Surface Methodology (RSM) was employed for establishing a quadratic relationship between input and output parameters. Analysis of variance (ANOVA) was then conducted for the evaluation of the proposed formula. RSM was also used for the optimization analysis that followed for the determination of milling cutting parameters for minimum surface roughness. The analysis indicates that the use of BBD can reduce the number of experiments needed for modeling and optimizing the milling operation of Titanium alloys. Furthermore, this method is able to provide models that can reliably be used for any cutting conditions within the limits of the input data. Finally, Artificial Neural Networks (ANN) models were developed to allow for a more robust simulation model to be built and comparison between ANN and RSM models to be performed. From the presented results, for RSM, the mean square error and the correlation coefficient were determined to be 8.633 × 10⁻³ and 0.9713, respectively; for ANN models, the corresponding values were 2 × 10⁻³ and 0.9824, for the test group of the optimum model. Simulations indicated that, although input data were too few, a considerably reliable ANN model was able to be built and despite of its complexity compared to RSM model, it was proven to be superior in terms of prediction accuracy.     

Lubrication of aluminium–silicon surfaces with ZDDP and detergents

Abstract

A review of the lubrication of aluminium–silicon (Al-Si) substrates by zinc dialkyldithiophosphate (ZDDP) and detergent engine oil additives is presented. Greater attention has been paid to understand the interactions of ZDDP, rather than detergents, with the aforementioned non-ferrous substrates. Zinc dialkyldithiophosphate generates tribofilms on both aluminium and silicon regions of aluminium–silicon alloys. However, film formation is believed to occur on silicon grains within the alloy, and those layers observed on aluminium regions are material transfer or the product of ZDDP thermal decomposition. There were many similarities in terms of film thickness, reduced elastic modulus, tribochemistry and topography of ZDDP derived tribofilms on both ferrous and Al–Si substrates. Calcium carbonate based films were observed on silicon grains when the aluminium alloys were lubricated with overbased calcium sulphonate, the tribochemistry and topography of which were similar to layers formed on ferrous substrates. When lubricated with either fully formulated oil or lubricants containing both detergent and ZDDP, the subsequently generated films were of varying chemistry, but often contained zinc or calcium phosphate compounds. The antiwear characteristics of ZDDP and calcium sulphonate tribofilms on ferrous and aluminium–silicon substrates are discussed, with the mechanical and film thickness data for such layers presented.     

Influence of microstructure and texture on the corrosion and tribocorrosion behavior of Ti–6Al–4V

In this paper, the corrosion and tribocorrosion behaviors of Ti–6Al–4V alloy having different phase composition, texture and microstructure was investigated. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were performed to evaluate the corrosion behavior. Sliding wear tests under anodic and cathodic polarization conditions were made to assess the tribocorrosion properties. SEM, OM, and XRD were used to characterize the microstructure, texture, and morphology of the samples. The corrosion resistance was found to depend on to the microstructure, as well as the texture of the surface. A bi-modal microstructure and prismatic texture showed the best corrosion behavior. However, when corrosion was coupled to sliding wear (tribocorrosion), the hardness was found to be the controlling factor.     

Influence of the Addition of Vanadium Nitride on the Structure and Specifications of a Diamond–(Fe–Cu–Ni–Sn) Composite System

This article discusses the influence of the addition of vanadium nitride on the mechanical and operational properties of diamond composite material based on metallic bond comprised of iron, copper, nickel, and tin obtained by sintering in a mold at 800°C for 1 h with subsequent hot repressing. It has been established that the addition of vanadium nitride in the amount of 2 wt % to diamond–(51Fe–32Cu–9Ni–8Sn) increases the ultimate compressive strength from 846 to 1640 MPa and bending strength from 680 to 1120 MPa, as well as decreases the wear intensity of the composite material from 0.0069 to 0.0033 g/km. The mechanism of improving the tribological properties has been revealed.     

Justifying Calculations of the Security of Promising Machines and Man–Machine Systems on the Risk Criteria of Accidents and Disasters

Further development of calculation and experimental analysis methods and ensuring their security against risk criteria for the prevention of accidents and disasters is considered. Of particular importance in this direction are the methods and technologies of both computational and physical modeling and analysis of the limiting states of structures leading to catastrophic failure. It is shown that the most promising direction of creating an effective apparatus for risk assessment and analysis of the security of technical systems can be considered the use of hybrid methods that allow taking into account both stochastic and interval uncertainties of the risk parameters in determining the safety and security conditions of man, the technosphere, and nature from manmade accidents and disasters.     

An experimental study of the hadron calorimeter module response to protons and pions with energies of 1–5 GeV

The design of the hadron calorimeter module is discussed. Such modules are expected to be used in the forward calorimeters of the Multi Purpose Detector (MPD) (Dubna, Russia) and Compressed Barionic Matter (CBM) (Darmstadt, Germany) experiments. The module has transverse dimensions of 20 × 20 cm² and is composed of 60 16-mm-thick lead layers interleaved with 4-mm-thick scintillator plates. Light from scintillator plates is captured by wavelength-shifting optical fibers. The module has longitudinal segmentation and consists of 10 sections. Light collected from each section is read out by micropixel photodiodes with a sensitive area of 3 × 3 mm². Test measurements of the energy resolution and linearity of the calorimeter module response in the hadron momentum range of 2–6 GeV/c have been performed. The longitudinal profiles of the hadron shower, obtained in the measurable energy range both for pion and proton beams, are discussed. The measured energy resolution and the linearity of the calorimeter module response at low energies are presented and compared to the data obtained at high energies.     

Comparative study of the tribological behavior of self-lubricating W–S–C and Mo–Se–C sputtered coatings

Transition metal dichalcogenides (TMD) have been one of the best alternatives as low friction coatings for tribological applications, particularly in dry and vacuum environments. However, besides their deficient behavior in humid containing atmospheres, their extensive application has also been restricted due to their low load-bearing capacity. In order to overcome these problems, recently the alloying with C has been tried with the expectation of simultaneously improving the coatings hardness and reaching sliding contacting phases more convenient for achieving low friction in humid environments.The practical application of this concept was extensively studied with the W–S–C system, with the C addition being achieved either by reactive or co-sputtering processes. The best tribological results were obtained by co-sputtering from a C target embedded with an increasing number of WS₂ pellets. Excellent results were reached from the more than one order of magnitude increase in the coatings hardness up to friction coefficients which are close to those of the references of self-lubricating coatings: TMD for dry or vacuum atmospheres or C-based coatings for terrestrial sliding conditions.Following the good results achieved with W–S–C system, other TMDs systems have been envisaged to be studied. The main focus was placed on the Mo–Se–C system.In this paper, the general comparison between W–S–C and Mo–Se–C coatings is presented. The main effort is pointed on the tribological behavior of both systems when tested by pin-on-disk against steel counterpart balls under different testing conditions: applied normal loads, temperatures and relative humidity of the atmospheres. Both coatings were deposited by co-sputtering from a C target with a varying number of TMD pellets which could lead to C contents in the films in the range from 30  up to 70 at.%. A Ti interlayer was interposed between the films and the substrates for improving the adhesion.Typically, W–S–C films are harder than Mo–Se–C films. From the tribological point of view, W–S–C films are more thermally stable than Mo–Se–C films although the friction coefficients of these last ones are lower when tested in humid containing atmospheres.     

Antifriction and Wear Characteristics of Electrolessly-Deposited Ni–P with PTFE Composites

This aim of this study was to investigate the tribological properties of a self-lubricating Ni–P–polyfluorotetraethylene (PTFE) composite coating prepared by the electroless plating method. The effects of PTFE contents in the coating, load and rotation speed on the tribological behaviors were evaluated using a ring-on-disk wear machine. The results show that there was a distinct decrease in the average value of the friction coefficient from 0.33 to 0.12 at 70 N with an increase in PTFE content from 4.2 to 15.2 wt%. The coating of Ni–P–4.2 wt% PTFE had good antifriction and wear properties at a load of 30–70 N, and that of Ni–P–10.6 wt% PTFE had passable wear resistance and better antifriction at <50 N. Antifriction and wear mechanisms of Ni–P–PTFE are discussed in detail based on the results from micrograph and element analyses of the worn surface, subsurface stratum and wear debris analysis by scanning electronic microscopy (SEM), and energy-dispersive X-ray analysis (EDAX), respectively. The lubricating film (LF) generated during wear played a key role in the antifriction effect, which in turn was dependent on the integrity and thickness of the film determined by the PTFE concentration and wear conditions. The formation, fracture, and delamination course of the LF during wear were also analyzed and characterized.     

Comparison between rubber–ice and sand–ice friction and the effect of loose snow contamination

The application of sand particles is a common method to improve the friction of aircraft tires on snow or ice covered runways. Hence, an understanding of the prevailing rubber–ice and sand–ice friction mechanisms is of practical interest. Rubber–ice and sand–ice friction measurements were made with a British Pendulum Tester at temperatures between ?22 and 0 °C and the effect of loose snow contamination on top of the ice was investigated. The results (the response of the instrument) were expressed in a sliding length averaged friction coefficient μ_BP. Close to the melting point the friction of rubber on ice was low and increased with decreasing ice temperature. Below ?5 °C, reasonably high friction levels (0.2<μ_BP<0.5) were obtained between rubber and ice, but the friction level dropped drastically by the presence of a very thin layer of snow. The sand–ice friction level was less dependent on ice temperature and clearly not as much affected by the presence of snow, compared to rubber–ice friction. The micromechanisms involved in rubber–ice and sand–ice frictions were investigated by the application of etching and replicating technique (ERT) developed for the examinations of the dynamics of dislocations in ice during deformation.     

Nondestructive assessment of the cutting properties of wheels with a single-layer diamond–galvanic coating

A new approach to determining the cutting properties of a diamond tool with a single-layer diamond–galvanic coating is proposed. The method is based on determining the concentration of diamond grains in the working layer of the tool.     

Productivity and optimization of section-based automated lines of parallel–serial structure with embedded buffers

Automated production lines of a parallel–serial structure are most productive in the manufacturing area. Designers of automated lines segment into sections with several stations place buffers between the series of sections that enable increasing the productivity rate. The failure of one station leads to stoppage of only one section of the automated line, while other sections continue to work and machine parts are stored or consumed from buffers. In real production condition, the capacity of a buffer is limited, and a buffer can compensate only in part stoppages of sections in an automated line. This article represents a new analytical approach for calculating the productivity rate of the section-based automated line of a parallel–serial action with embedded buffers of limited capacity. It enables to solve the problem of structural optimization of the line by the criterion of a maximal productivity rate, which yields the optimal number of serial and parallel stations, and the number of sections.     

MAGE Spectrometer for the Investigation of Hadron–Nucleus Interactions and the Identification of Final Nuclear States

A combined spectrometer is composed of a wide-aperture magnetic spectrometer with proportional chambers and a -spectrometer based on a Ge(Li) detector. The respective momentum and the angular resolutions of the magnetic spectrometer are FWHM/p(%) = 0.59p (GeV/c) + 1.1 and 0.5–1 mrad; its average efficiency for 0°–5° angles is 85%. The energy resolution of the -spectrometer is 8 and 16 keV for 0.5- and 2.0-MeV photons, respectively; the average angular acceptance is 1.5 msr.     

Operational damage to the structure and failure of the KAMAZ truck spring in the temperature–load conditions of the North

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.     

Relations of counterface materials with stability of tribo-oxide layer and wear behavior of Ti–6.5Al–3.5Mo–1.5Zr–0.3Si alloy

Dry sliding wear tests of Ti–6.5Al–3.5Mo–1.5Zr–0.3Si alloy (TC11 alloy) sliding against AISI 52100 and AISI M2 steels were performed under the load of 50–250 N at 25–600 °C. For two kinds of counterface materials, the titanium alloy presented totally different wear behaviours as the function of temperature. The appreciable variations of the titanium alloy sliding against different counterface materials were attributed the fact that a hard counterface caused unstable existence of tribo-layers by its microcutting action, thus resulting in the increase of wear rate. It is suggested that the hard counterface must be avoided as the counterface for the titanium alloy/steel sliding system.     

Investigation of Die–Workpiece Interface Friction with Lubrication During the Upsetting Process

A thermo-elastic plastic model of a large deformation combined with a hydrodynamic lubrication model is developed in this paper. The former formulation solves the interaction between mechanical load and thermal load using the finite-element method and the finite-difference method in which the flow stress is taken as a function of strain, strain rate and temperature. While the latter one accounts for the different lubrication regions which may occur at different areas of the die–work-piece interface or at different times, and in which the full film lubrication and the mixed and boundary lubrication conditions are included. Thus, a realistic deformation behaviour can properly be modelled. The calculated forging load and the deformed shape of the workpiece are in good agreement with the results obtained from the upsetting experiment.