Advances in Science and Technology Vol. 170

Abstract: The optimal geometric dimensions and dependencies for gas mask filter boxes have been determined. The geometric dimensions of the filter boxes have been defined using comfort, performance, and efficiency coefficients. These coefficients have been established through computer modeling of airflow movement within gas mask filter boxes using the SolidWorks software. The base models for creating digital copies were two types of filter boxes: cylindrical and flat, which differed in their geometric dimensions.

Abstract: The intensity of neutralization of dangerous gases (chlorine, sulfur dioxide, hydrogen cyanide, phosgene, hydrochloric acid, ammonia) is researching during deposition with small-dispersion water. For this purpose, a mathematical model of neutralization of a dangerous gas, which is lighter than air, with fine water was modified for use in neutralizing a dangerous gas, which is heavy relative to air. The model takes into account the main parameters of sorption (environmental conditions, physical and chemical properties of the dangerous gas, parameters of the liquid flow supplied for deposition), which minimizes the forecasting time and is critical in the elimination of an accident with a release of dangerous gases. It was found that when dangerous gases are deposited in a finely dispersed water stream, the determining parameter is the Henry's constant of the dangerous gas, rather than the intensity of the fine water stream. It is confirmed that for dangerous gases that are poorly soluble in water (have small values of Henry's constant), it is necessary to add additives to the water stream that increase the chemical activity of the solution.

Abstract: The problem of axisymmetric bending of a ring plate, which is under the influence of a constant uniformly distributed transverse load and rests on a non-uniform elastic Winkler foundation, is considered. The inhomogeneity of the elastic foundation is given by a power function with an arbitrary non-negative power exponent . In analytical form, the fundamental functions and a partial solution of the corresponding differential equation are found. These functions are dimensionless and are represented by absolutely and uniformly convergent power series. In turn, formulas for the parameters of the stress-strain state of the plate are expressed through the specified functions. In fact, the calculation of the plate is reduced to the procedure of numerical implementation of explicit analytical formulas. The practical application of the obtained solutions is demonstrated using the example of a concrete slab with both fixed contours, resting on a cubic-variable elastic foundation

Abstract: The problem of bending of a beam of variable stiffness resting on a continuous homogeneous elastic Winkler-type foundation is considered. The exact solution of the corresponding bending differential equation is found for the case when the beam stiffness is an arbitrary continuous function. Based on the exact solution, an analytical method for beam calculation is developed. This method produces accurate results and is computationally efficient. It is implemented in a computer program and demonstrated by the calculation of a truncated wedge-shaped beam. The calculation results are provided in numerical and graphical formats.

Abstract: The purpose of the study is to numerically assess the durability of the glass covering the windows of a house located near the epicenter of an emergency explosion of a gas-air mixture at a hydrogen refueling station. It is assumed that the gas release into the air is a consequence of the failure of a high-pressure hydrogen storage tank. The influence of the height of the protective wall installed on the path of the shock wave propagation from the epicenter of the accident to the house on the degree of destruction of window glass depending on its type (ordinary, reinforced, tempered, laminated, and armored) is considered. Each type of glass is durable up to a certain range of the maximum excess pressure of the explosion wave in its front, which is characteristic of the degree of destruction (cracking, complete destruction). To obtain the distribution of the maximum excess pressure on the surface of the glass covering the windows of the house, the direct problem of the movement of the gas-air mixture through the space of the refueling station, which covers the epicenter of the explosion, the protective wall and the house with windows, was considered. To generate the blast wave, a model of the instantaneous explosion of a hemispherical cloud of a stoichiometric hydrogen-air mixture is used, which is based on the Euler equations with source terms of turbulent diffusion. The system of equations is a reflection of the laws of conservation of mass, momentum, and energy of the mixture, which is closed by the equation of state of the mixture and supplemented by the law of conservation of hydrogen combustion products. The Godunov method is used to solve the system. The solution is a non-stationary three-dimensional pressure field, which is the source of the distribution of the destructive factor (maximum excess pressure) on the window glass. Deterministic analysis of the durability of window glass to the action of the blast wave consists of comparing the obtained distribution of the value of this factor with reference data for each type of glass and the degree of its destruction. The presented methodology can be recommended for choosing the type of window glass and the required height of the protective wall at the design stage of a building of such a dangerous technogenic facility as a hydrogen filling station.

Abstract: The need to study the fire hazard of typical premises of a mobile communications base station was substantiated, in particular, regarding the feasibility of equipping it with an automatic (self-contained) fire-fighting system. Criteria for assessing the fire hazard of a mobile communications base station were developed. It was experimentally established that the greatest fire hazard in the premises of a mobile communications base station was related to the following devices: Alarm Box switching panel, input and distribution board, internal air conditioner unit and 12 V 100 A#2 batteries. Moreover, the latter two ones contribute to the spread of fire inside the premises. During the ignition of the 12 V 100 A#2 batteries, it was established that the surface of the outer wall further heated to a temperature of 80 °C, which did not exceed the critical one. Thus, the fire did not spread beyond the premises. It was established that equipping the premises of a mobile communications base station with a fire-fighting system in order to prevent the fire spreading beyond its boundaries was unreasonable.

Abstract: The article is devoted to the analysis of the operational suitability of the aircraft shelter structure under the action of an explosion, taking into account the nature of their spread through the soil backfills. The intensity of the decrease in the bearing capacity of the covering structure, which depends on the content of reinforcement in the structural element, is considered. Including, preventive measures are proposed for the progressive collapse of the hangar roof slabs in the event of a possible missile hit. The article considers various scenarios of explosive effects, under which the worst-case conditions for ensuring the reliability of the hangar structure during emergency effects were checked. Wave propagation during a ground explosion was analyzed. An example of calculating the arched hangar structure for a blast wave in the LIRA-FEM PC under the action of a surface explosive effect is provided. The results of the nonlinear calculation of the arch and the roofing slabs with an additional impact load of up to 20 tf/m² are presented. The modeling of the nonlinear loading process was carried out taking into account the damping of the soil base of up to 10% on an area of up to 80 m² with a dynamic coefficient of 1.2 in the PC LIRA-FEM, the calculation of the emergency load was performed with the specified TR (type of reinforcement).

Abstract: The paper presents experimental and computer researches of ferroconcrete beams at high-temperature influences. There were conducted the experimental fire tests of ferroconcrete beams. The most promising way of verifying these experimental research data is computer simulation of structures, also during a fire. In order to evaluate the quality of the experiment and the reliability of the received temperature distribution.

Abstract: The article presents the results of the depth of charring of wooden beams with fire-retardant cladding with OSB plates and fire-retardant plywood during fire tests under standard temperature conditions. The aim of the work was to identify changes in the geometric parameters of the charring zone of a wooden beam as a basis for calculating the design data for the strength of these beams. To achieve the aim, the following tasks were set: to determine that the contours of the charred zone in the cross-sections of wooden beams with fire-retardant cladding can be described using isotherms with a critical temperature of charring initiation; to develop a method for mathematically describing the geometric shape of the charring zone in the cross-section of the beam by approximating the contour lines of this zone using Bézier lines.