R.К. Prilepskij, E.S. Sаvеnко, S.V. Krakhin, R.I. Rybalko
Questions of pneumatic perforators dynamics
Donbas National Academy of Civil Engineering and Architecture
Abstract. In the article the results of pneumatic perforators dynamics researches have been stated on the basis of differential equations system of variable mass body thermodynamic and the dynamic piston. The detailed analysis shows that the changeability of thermodynamic body mass takes place in the working process of pneumatic perforator and undoubted by influences on the character process, which determines the initial equalization system choice. The given equations systems do not have the general solution, but they have private of solution, being of interest in theoretical research of working process. The method of pneumatic perforators comparison has been worked out on the principle of similarity (the criteria of similarity are obtained), allowing to spread the single researches results on all types of the size row. At present calculation the methods of air distributed devices for perforators have been worked out not in enough detail, and the static’s questions have mainly been considered, that does not allow to analyze workings processes taking into account the dynamics and thermodynamics of air distributed devices, and hence from the point of the similarity theory.With the purpose of the method elaborations, which allows calculating of the supposed graph of valve motion the differential equations have been suggested, characterizing the working process of the most widespread types of air distributive devices of pneumonic hammers, and indicated the methods of their solution.
Key words: perforator, piston, dynamics, equalization, criterion, valve, thermodynamics, pressure, mass.
R.N. Pavlovskiy, S.G. Kuznetsov
Modelling of atmospheric ground boundary layer in short air dynamic tubes wind tunnels
Kiev’s national University
Donbas National Academy of Civil Engineering and Architecture
Abstract. The paper represents a new method of modeling overground athmospheric boundary layer for air dynamic tubes with the short working part to adapt laboratory installations for constructions tests. Classic air dynamic tubes have short working sections (not less than the section height) with the low turbulence. From the wind engineering modeling requirements it is clear that to obtain exat results it is necessary to model the atmospheric boundary layer. When designing, the strong wind is subjected to tire insignificant influence of thermal stratification is the most important factor. That is why the running is flow is usually isothermal, which models thermally neutral atmospheric boundary layer. Aerodynamic tubes, elaborated for sush a flow type are classified as the aerodynamic pipes with boundary layer. The new generator vortex gives the opportunity to provide the steeples regulation of boundary-layer thickness, the same vortex-generators using and at the expense of this experimental possibilities of the numerous existing aviation aerodynamic tubes with short operating section, enables to carry out the meteorological investigations in them.
Key words: atmospheric boundary layer, aerodynamic tubes, wind engineering, modelling wind flow.
V.V. Stoyanov, A.I. Davidenko
Increasing durability and deformability of wooden beams
Odessa state Academy of civil engineering and Architecture
State Scientific Research Institute of Building Constructions
Abstract. The article is devoted to the known calculation approaches to wooden beams at the cross bending. Taking into account the work peculiarities of timber at different stress states, new methods are based to increase bearing capacity of wooden bent elements. Thereupon the wood is considered as natural polymer composed of tubular fiber system. The attention is paid to new plastic kind of work of the timber under pressing where the main role is determined by the amorphous part of the cellulose fibers which may be modified that leads to the enhancing of durability and rigidness while compression.
Key words: wood, cellulose, automated icing monitoring system, the increase of hardening and stiffening.
M.U. Mazanik, A.A. Redko
Burning of coal methane in the diffusion bottom burner
Kharkiv State Technical of Civil Engineering and Architecture
Abstract. The article the burning process of features of low calorific value of gases in the diffusion bottom burners, on the basis of which the modeling mechanism of carbon monoxide and nitrogen oxides have been assumed. The results of numerical researches as for the burning of coal methane production in the retrofit bottom burner and modificated for combustion of coal methane. The results on temperature fields and velocity fields, the distribution of СО, О2, Nox, СН4 and other components have been obtained. On the basis of the value speed calculation and temperatures of the modified burner is lower than in the series one, as well as the ecological parameters have lower values.
Key words: coal methane, diffusion burner, energy and economical characteristics.
A. A. Petrakov, N.A. Petrakova, N. G. Lobacheva
Practical methods of the limited conditions analysys of the foundations and the bases
Donbas National Academy of Civil Engineering and Architecture
Abstract. Methods of limiting conditions analysis of the bases, the foundations and the ground masses, based on the the mixed problem solution of the theory of elasticity and plasticity are considered. Problems of numerical realization of algorithms of such methods nave been analyzed. The information about features of numerical methods realization of the limited conditions analysis by the step-by-step method considering the structure destruction scheme in the computer complex «Nonlinear Polyfem». The essential Puasson’s coefficient influence on the solution of the elastic and plastic problem. The methods numerical realization is illustrated by examples of calculation of the wall landfall and foundations, the LPT Recommendations of the algorithms elaboration based on the solution of an elastic-plastic problem, with application of the relaxation factor providing the group transition of final elements in limited conditions and allowing to avoid of the machine cycling.
Key words: nonlinear analysis bases and foundation, mixed problem of the theory of elasticity and plasticity.
М.К. Pakter, А.I. Sereda, V.I. Bratchun, V.L. Bespalov, L.А. Gorbanova
Photo and oxide ageing of polyamide
Ukrainian Scientific Research Institute of plastic masses
Company «Netlayn»
Donbas National Academy of Civil Engineering and Architecture
Abstract. Using the complex of experimental researches methods (the devise artificial weather of IP1-3, machine being under test on axial tension UTS-10 with diagram «tension (?р) construction is deformation (?в)», the method of DSK is a scanning calorimetry (the temperature increasing speed 10/K minute), infra red spectroscopy, electronic microscopy) a photo oxidation ageing of polyamide polymers. It is set that for the initial stabilized and unstabilized polyamide specimens of (before photoamyde ageing) the depence diagram ?-? has three natural areas: the first area is the linear dependence between ? and ?; the second area is the plastic flow; the third area is the brittle destructions of polyamide. While the increasing of light display intensity, that is light quantity H at Н=2,02·106 lk hour both stabilized and non-stabilized PA-6,6 becomes rigid and brittle. It’s essentially, that while polyamide radiation with ultraviolet rays in presence of oxygen of air with temperature of 60°C, the durability of specimens of PA-6,6 increases at first, and then goes down. It has been confirmed that shortly waved U.V. radiation in combination with oxygen of air, the temperature and moisture causes the serious changes in the surface layer. In this case photochemical reaction leading to the brittleness first of all of amorphous areas of polymer, which is the factor of decreasing relative elongation while breaking. It ha been set that the quantity of oxidating products decreases from the surface into the film depth. While the increasing the radiation duration amount of cracks increases in specimens, turning yellow no stabilized polyamide. For PA while radiation action of small wave-length U. V. (<300 нm) the break of chain is dominant between the atoms of carbon and nitrogen. Because of high reaction ability of nitrogen containing end radicals there is formation of amynogroups and the oxide of carbon is emussed.
Key words: a photo is the oxidizing ageing, polyamide, nonstabilized and stabilized PAS-6,6, radiation of polyamide, Ultra Viole is radiation, temperature, photo chemical reactions.