This study contains main views and scientific principles of its authors, used as a basis for mathematical modeling, oriented to the synthesis of kinematically conjugated spatial (hyperboloid) gear drives.
Machines. Technologies. Materials.
Vol. 12 (2018), Issue 5
Table of Contents
The aim of this study is to design a 3 Unit CubeSat structure performing finite element analysis under static, dynamic and thermal loads. The main idea of this process is to construct a 3U CubeSat main frame that can structurally endure launching process and space environment. To accomplish the task, a 3U CubeSat structure is designed and standard loads that a 3 unit CubeSat structure has to endure are obtained. After the selection of a suitable material, modal analysis, quasi-static launch analysis and thermal stress analysis coupled with heat transfer analysis are accomplished in Abaqus environment. Finally, the results are evaluatedand endurance level of the
design is determined.
In this article some of main characteristics of caterpillar vehicle’s straight motion are depict. An analytical method for working out formulas for maximum speed, acceleration and time and route for acceleration is suggested.
The article deals with the process of wave forming on the surface of a liquid in a chamber of a liquid auto-balancing device partially filled with a liquid for rotors with a vertical axis of rotation under non-stationary modes of the system’s motion. In non-stationary processes, the possible wave formation causes a dynamic instability in the operation of the machine and the increase of vibrations under certain operating modes. In the article the problem for the case when the rotor is installed in elastic supports is solved, the joint movements of the rotor – liquid system are considered and their stability is investigated.
NATURALLY ASPIRATED GASOLINE ENGINE UPGRADE WITH TURBOCHARGER – NUMERICAL INVESTIGATION OF CHANGE IN OPERATING PARAMETERSpg(s) 204-207
Numerical investigation of naturally aspirated gasoline engine main operating parameters and engine upgrade with a turbocharger is presented in this paper. Analysis is performed by using numerical 0D (zero-dimensional) simulation model. Turbocharging process with a selected turbocharger increases engine maximum torque for 62.58 % and also increases maximum engine effective power for 58.82 %. One of the main reasons of turbocharging process usage is reduction of engine brake specific fuel consumption. The highest decrease in brake specific fuel consumption for a turbocharged engine, in comparison with naturally aspirated one, is obtained at 4000 rpm and amounts 8.83 g/kWh (from 239.01 g/kWh for naturally aspirated engine to 230.18 g/kWh for a turbocharged engine). Turbocharging process brings several useful benefits to the analyzed gasoline engine, which is also a valid conclusion for internal combustion engines in general.
At the time of exploitation, the geometrical position of the control valve changes as a result of wearing, which leads to a change of residual electromagnetic gap stroke and force of control valve spring. The following study measures the hydraulic characteristic changes, based only on common rail injector increased stroke of control valve and residual electromagnetic gap. The results show that the increasing of control valve stroke and residual electromagnetic gap increase the fuel flow rate and return fuel flow. Increased fuel flow rate and return fuel flow are presented with short injector signal time and lower levels of working pressure. The increasing is lower with longer injector signal time and high level of working pressure. The follow-up results are practically significant by common rail electromagnetic injector diagnosing and repairing.
DEVELOPMENT AND IMPROVEMENT OF TECHNOLOGIES FOR PRODUCING STRUCTURAL MATERIALS WITH ULTRAFINE-GRAINED STRUCTURE BY SEVERE PLASTIC DEFORMATIONpg(s) 212-215
Paper presents an overall analytical review of recent achievements in the field of development and improvement of technologies for producing structural materials with ultrafine-grained structure by severe plastic deformation. Main modern methods of obtaining ultrafine-grained structure by severe plastic deformation are described. Special attention to combined process “helical rolling – pressing” is devoted.
Because of the combination of high specific strength and excellent corrosion resistance in many media, titanium and titanium alloys are used in aerospace engineering, chemical industry, mechanical engineering etc.
The present work introduces results that demonstrate the effect of the thermal cycle on mechanical properties of Grade 1 Titanium welds, produced by hollow cathode arc discharge in vacuum. Dimensions of the welds were established. The mechanical properties of the welds – hardness and tensile strength – were determined. The influence of the thermal cycle on welds structure was investigated.
PECULIARITIES OF CHEMICAL-THERMAL TREATMENT OF SEMI-PERMEABLE POWDER METALLURGICAL MATERIALS IN SEMI-PERMEABLE SATURATION MEDIApg(s) 219-221
The main characteristic of the powder metallurgical materials that distinguishes them from the summer ones is the presence in them of residual porosity. For this reason, the processes of their thermochemical treatment are differ significantly from those occurring at saturation of dense ones. In the present paper the impact of technological processes such as boronizing, chromizing, siliconizing, carburizing, borocarburizing, etc., is monitored on the kinetics of diffusion layer growth in powder materials with a porosity of 5÷35%. The specimens of iron powders NC 100.24 and those doped with 2% Cu were subjected to study. The samples were pressed with an effort of 200 ÷ 800MPa and sintered for 0.5h at 1150°C in dissociated NH3 medium. Thermochemical treatment was conducted at 950°C for 4 hours in semi-permeable saturation media. Graphical dependencies for varying the thickness of diffusion coatings in different thermochemical treatment modes are presented, depending on the porosity of the saturation materials.
Titanium dioxide coatings and zirconium dioxide were deposited on SiO2 underlayers by sol-gel method on stainless steel plates. The samples were treated at two different temperatures (500 and 700oC) in air. The morphology was examined by means of Scanning electron microscopy (SEM) and the phase composition by X-ray diffraction analyses. The corrosion resistance of the coatings were examined by evaluation of the weight loss in NaCl medium. The TiO2/SiO2 coatings possess relatively smooth surface with some crystallites on the surface, while ZrO2/SiO2 coatings are not so smooth. After treatment at higher temperature the ZrO2/SiO2 coatings become rougher. The weight loss measurement have proved that the TiO2/SiO2 coatings exhibit higher corrosion resistance in comparison to ZrO2/SiO2 coatings. The TiO2/SiO2 coatings, treated at 500oC after the corrosion test retain their characteristic grain structure without any cracks and other defects. Similar is the structure of these coatings, treated at 700oC. The better protective properties of TiO2/SiO2 could be attributed to their amorphous dense structure.
In this paper, in order to dimension the position and the number of vertical reinforcement, several numerical linear static simulations of bending circular manhole cover of ductile cast iron (grade EN-GJS-500-7) with 600 mm diameter are performed. The analysis of displacement and stress using the finite element method in the software package Autodesk Simulation Mechanical were conducted. Verification of numerical results for the solution of thin circular plate was performed with analytical bending solutions. After checking the numerical procedure on the thin circular plate, two circular vertical reinforcements were added on the underside: internal and external. Numerical simulations investigated the influence of the inner circular reinforcement position on the strength of the circular manhole cover, while equivalent stresses followed by energy theory of strength (von Mises) were monitored. Since maximal equivalent stresses remain on the plate by varying the position of the inner circular reinforcement, simulations with added radial reinforcements are performed. Finally, by optimizing the number of radial reinforcements, the optimum plate design is chosen.