O.I. Demidov
An Elastic-Plastic Stressed-Deformed State of a Thin Unclosed Toroidal Shell
Donbas National Academy of Civil Engineering and Architecture
Abstract. The work is devoted to the application of the earlier developed methods of determining an elastic-plastic stressed-deformed state of arbitrary shape shells in terms of the theory of small elastic-plastic deformations. There are considered the problems under a simple shell loading. The problem linearization is done by the method of elastic solutions. In every approximation, there are considered the problems of the theory of thin elastic shells by the method of d finite differences in terms of the Lagrange variational equation in the median surface points travel. When writing the Lagrange variational equation, the relation between stresses and deformations is given in the form of the Hooke’s law but with additional terms considering plastic deformations. Geometrical equations are accepted in the linear formulation in the form of Саuсhу’s correlations. The material is characterized by a corresponding tension diagram of a cylindrical specimen, by the standard modulus of elasticity, and by the Poisson’s ratio. The equations of a toroidal shell medium surface are written in a parametric form. The shell inner and outer edges are absolutely rigidly packed, and the sides are jointed. There is given a numerical design of a thin unclosed elastic-plastic toroidal shell of a constant thickness under the action of an equally distributed normal load in the in the median surface points travels. There is applied a method of elastic solutions together with the variational- differential method in the median surface points travels. The problem solution is brought to numerical results. There are presented the fields of intensity of tangential stress through the shell thickness at an elastic-plastic solution of the problem for the whole net domain for three values of an equally distributed load. There was determined the load value under which there appear the first plastic deformations. In the figures there is shown a development of plastic zones as an equally distributed standard load grows. The work is devoted to an urgent question of the shells structural mechanics at their elastic-plastic deformation in terms of a shell simple loading.
Key words: an unclosed toroidal shell, the variational-differential method, boundary conditions, the method of elastic solutions, an intensity of a shift deformations, an intensity of tangential stresses, the function of plasticity.
Ye. V. Horokhov, S. G. Kuznetsov
Mechanism of the Interference Effect on Determination of Wind Loads
Donbas National Academy of Civil Engineering and Architecture
Abstract. Wind loads on buildings are mainly evaluated by using the building codes and specifications for the most part based on the wind tunnel tests carried out for the open terrain structures. But as shown by some researchers, wind loads on a building in an actual environment can greatly differ from those measured on an isolated building. Adjacent structures can either decrease or increase the wind flow induced actions on a building depending mainly on the geometry and location of these structures, their orientation relative to the flow direction and characteristic properties of the adjoining territory. Hence, this effect known as interference should be taken into account by designers and planners. In this article, there are considered and analyzed the researches into the field of the interference effect. The article mainly deals with the wind load modifications under the interference effect influence. To give common practical recommendations to designers and planners, a systematic approach to study the problem of interference is needed to describe, compare and evaluate the experimental data available, to specify common points of contact and spheres under consideration, and on this basis to formulate common recommendations and limiting conditions. The interference mechanism has been explicitly described on the basis of experimental results.
Key words: interference effect, a tall house, wind loads.
S. A. Gorozhankin
Determination of the Actual Cycles Parameters of the Stirling Engine on the Basis of their Adiabatic Model
Donbas National Academy of Civil Engineering and Architecture
Abstract. There has been developed a method of calculating and optimizing parameters of Stirling engines on the basis of the adiabatic model of their thermodynamic cycles. An engine generalized scheme is introduced, and the order of calculating its parameters relative to the heat exchange processes in its internal operating contour, external contours of a heater and cooler is determined. Compression and expansion processes in cylinders are considered as adiabatic. Hydraulic losses of a working body energy in the internal contour and external devices are taken into account. Energy losses at heat exchange and heat regeneration are analyzed. Energy expenses to drive auxiliary units, mechanical losses on friction are calculated. Internal and effective efficiency factors of engines are determined. The calculation results by the isothermal and adiabatic models are compared, and their comparison with the experimental data for pilot engines is done.
Key words: Stirling engine, a thermodynamic cycle, an adiabatic model, an internal contour, heat losses, mechanical losses, an efficiency factor.
V. G. Kolesnichenko, A. M. Yugov
On the Calculation of Metalwork for Assembly Loads and Effects
Donbas National Academy of Civil Engineering and Architecture
Abstract. There are considered the issues of the design estimation of the parameters of a metalwork stress-deformed state when assembling buildings and structures. On realization of the technologies of metalwork assembly, there generally occur a lot of design states that are characterized by permanently changing parameters of a structure design scheme. The existing design codes of metalwork do not contain any postulates on the rules and procedures of estimating a structure behavior when being assembled. There are analyzed the types of the assembly states and design schemes of structures under different assembly conditions. As the types of the assembly states there are considered the stages of transportation, storage, enlarged assembly and installation of structures or assembly units into a design position. There are put forward the approaches of estimating a metalwork stress-deformed state parameters on their assembly. It is suggested here to work out recommendations to be added to the existing design and assembly codes for metalwork and structures to design their assembly states.
Key words: metalwork, transportation, enlargement, assembly, design states, stress-deformed state.
V. M. Kushchenko
Dangerous States and Reinforcement of Building Structures of Sloping Head-Frames
Donbas National Academy of Civil Engineering and Architecture
Abstract. In the article there are given the results of studying the processes of physical wear of building structures of sloping head-frames. The main types of aggressive influences are corrosion and abrasion media; mechanical influences, such as impulses and impacts; operational imperfections. For head-frame structures, there have been fixed three operational zones, all of them being homogeneous by the composition and aggressive media intensity. Four basic stages of physical wear have been determined and their dangerous states have been classified. There have been also stated principles of reinforcing for different stages of physical wear. The cross-section losses of constructive elements being up to 30%, the latter can be reinforced by the built-up method. The cross-section losses of constructive elements more than 30%, head-frame structures, it’s a good idea to reinforce head-frames by internal and external duplication of basic carrying structures. While reinforcing the structures of head-frame beds installed on the fangs, air-tightness should be taken into account. A rational constructive form of the head-frame bed structures are laminated structures reinforced by stiffening ribs located on the outside.
Key words: sloping head-frames; aggressive influences; physical wear; reinforcement of building structures.