Permissible Load Research Articles

Construction of a prototype of the basic module of a scalable robotic system for simulation of composite surfaces for dynamic tests

The authors of the article developed a mathematical model of Stewart platform management. The angles of rotation of the servo shafts were obtained when setting various laws of motion of the mobile platform, in matrix mode. The hardware part of the prototype of the basic module of a scalable robotics system for modeling composite surfaces for dynamic tests was developed. The results of calculations of the maximum permissible load on the shafts of servos are presented. The CubeIDE settings for programming the STM32 microcontroller are given. The results of software development for the control of this prototype were obtained, namely, a library for controlling 6 servo drives under driver control was written. The problems that may arise during the above-described developments by future developers are considered, solutions to these problems are obtained. Detailed design features of this prototype are described, the control code of the servo drive is given; steps for further development of the final robotic system are considered

Load transfer behavior of 3D printed concrete formwork for ribbed slabs under eccentric axial loads

3D printed concrete (3DPC) has primarily been used for non-structural applications, with limited exploration into its potential for structural load-bearing applications. This is mainly due to the layered structure of 3DPC and the lack of compatibility of conventional reinforcement strategies to be integrated within the 3D concrete printing process. The post-tensioning of 3DPC structures presents an effective solution to improve the load-carrying capacity and cracking behavior of 3DPC. However, understanding the load transfer behavior and failure modes of 3DPC structures under a particular post-tensioning configuration are crucial to determine the permissible post-tensioning load for a structure without premature failure and to understand the distribution of stresses within the concrete structure under post-tensioning loads. The current study aims to investigate the load transfer behavior and failure mode of a 30 mm thick 3DPC formwork designed for one-way ribbed slabs when subjected to end-anchorage post-tensioning. For this purpose, a series of mechanical characterization and load transfer experiments were conducted on ribbed 3DPC formwork. The mechanical characterization investigations involved examining the compressive and flexural strength, as well as the elastic modulus of 3DPC, under various loading orientations relative to the print path. In the load transfer experiments, the end anchorage post-tensioning system was simulated by applying the axial load to the specimen via end plates bonded to the specimen. The variable parameters of the load transfer experiments were the boundary conditions, the eccentricity of the axial load from the neutral axis, and the topology of the ribbed 3DPC formwork. A digital image correlation system was used to study the axial and transverse strain evolution during the load transfer experiments. The experimental results showed that, regardless of the eccentricity of the applied load, the ribbed 3DPC formwork specimens exhibited higher axial load capacity when the load was applied near the bottom flange rather than the top flange. This was because of the reduced effective cross-sectional area for compression when the load was positioned near the top flanges, a consequence of the selected formwork topology, where top flanges were discontinuous to allow for pouring of the cast concrete within the formwork.

Development of a calculation power model of a vacuum automounting device

One of the ways to improve navigation safety during water transport operation is to develop automated devices and systems that reduce the number of tasks for workers. For example, the introduction of vessels with different levels of autonomy into production activities, capable of automatically monitoring the environment or delivering cargo, helps to reduce the size of the vessel due to the absence of a residential superstructure. On inland waterways, one of the limitations of the introduction of autonomous navigation is their safe passage through shipping passages — shipping locks. Mooring a vessel in a lock chamber is very labor-intensive and is usually performed by crew members of the vessel being locked for movable (floating hoops) or fixed (berthing bollards, bollards, hoops) mooring devices, the permissible loads of which are established in regulatory documents. Over the past 10 years, the authors have not found studies describing the results of measuring the loads on mooring devices and ropes arising from the movement of the vessel in the lock chamber. Another constraint to the implementation of autonomous shipping is the lack of requirements for auto-mooring devices that ensure the retention of vessels in the lock chamber. In this regard, the purpose of this study is to compare the standard and actual values of the load on mooring eyes and ropes for the theoretical calculation of the holding forces of the vacuum automooring device model, taking into account the operating conditions in the shipping lock chamber. The measurement results presented in the article were obtained in the course of the research work “Development of scientifically based recommendations for establishing hydraulic modes for filling and emptying the chambers of locks No. 1–8 of the Federal State Budgetary Institution “Volga-Balt Administration” based on in-kind studies of the conditions of ship mooring in lock chambers” commissioned by the Federal Agency for Maritime and River Transport using a strain gauge installed in the mooring rope cut. As a result of the theoretical calculation of the holding force of the vacuum auto-mooring device, the holding forces of the vacuum gripper from the radius of one vacuum suction cup were obtained.

Calculation of Maximum Permissible Load of Underground Power Cables–Numerical Approach for Systems with Stabilized Backfill

The maximum permissible load of underground power cables (known in U.S. engineering as “ampacity”) is a function of many parameters, in particular, the thermal resistivity of the native soil. If this resistivity is relatively high, thermal/stabilized backfill is applied, i.e., another material is placed around the cables, providing favourable conditions for heat transfer to the environment. It has a positive impact on the reliability of the power supply and favours the operational durability of the cables. In design practice, however, there is a difficult task—correct determination of the ampacity of the cable line depending on the thermal parameters and the geometry of the backfill. Therefore, this article presents the results of a numerical analysis to determine the ampacity of cable lines in which stabilized backfill is used. A new mathematical relationship is proposed that allows the correction of the ampacity of cable lines depending on their cross-section as well as the thermal and geometric parameters of the cable surroundings.

Methods for ice crossings load capacity calculation

Introduction. The article deals with a problem relevant to the territory of our country – the calculation of the bearing capacity of ice crossings and winter roads. This problem is becoming more and more urgent in connection with the development of the northern territories, an increase in the carrying capacity of road transport and the volume of cargo traffic. At the same time, the construction of permanent roads and bridge crossings requires very large capital expenditures, which are not yet available for the Russian Federation.Methods and materials. A critical analysis of methods for determining by calculation the bearing capacity of ice cover at crossings (the maximum permissible load on the axle of a single car or road train) was carried out.The recommendations of normative and methodological documents on this issue are considered. The presented analysis of domestic and foreign publications made it possible to evaluate mathematical models of different levels of complexity and detail, with a different set of factors influencing the final result.Results. As a result of the research, a summary table, which contains formulas for calculating the bearing capacity of the ice cover, the parameters that are taken into account in these formulas, as well as the values of the bearing capacity calculated using these formulas for two temperatures: 0 °C and minus 20 °C has been compiled.Conclusions. According to the results of the analysis, it can be seen that the largest number of parameters is taken into account in M.M. Kazansky-R.A. Shulman; Q. Wang; ODM 218.4.030-2016 Methodological recommendations for assessing the carrying capacity of ice crossings’ dependencies. At the same time, the value of the bearing capacity, calculated according to the 11th formulas, varies by 2-3 or more times presented. Consequently, the presented mathematical models for predicting the carrying capacity of ice crossings require experimental verification on real objects by dragging the control cargo (with some refinement of this method).

Long-Term Permissible Load Currents of Single-Core Cables with a Voltage of 10 kV with Cross-Linked Polyethylene Insulation of Various Designs

Long-Term Permissible Load Currents of Single-Core Cables with a Voltage of 10 kV with Cross-Linked Polyethylene Insulation of Various Designs

Assessment of the impact of agricultural tractor wheels on soil compaction

Abstract This article presents the results of an experimental study on the impact of leading wheel tires 15.5R38 and 16.9R38 on soil. Specifically, the study analyzed the influence of vertical load on the maximum tire pressure (MTA) and internal air pressure on soil. The variations in maximum soil pressures of 15.5R38 and 16.9R38 tires at different internal air pressures depending on corresponding loads were investigated. The characteristics of changes in permissible pressure and loading of tires on soil are graphically depicted, and the permissible standards for their use in agricultural work are determined. Recommendations are provided for using tires at the minimum and maximum permissible internal air pressures. Using values smaller than the recommended values can lead to a decrease in the useful life of the tire.

A method based on GA solver for optimizing the design parameters of the right frustum resistance frame for indoor earthquake shelters

This paper proposes a new method to enhance the impact resistance of earthquake shelters. Traditional methods for protecting individuals during earthquakes focus on improving or reinforcing the building structures, which is time-consuming and inflexible. The SHELTER project developed an earthquake shelter using a conventional cubic frame. This study builds upon the SHELTER project by optimizing its frame structure to improve the shelter's impact resistance against falling debris during an earthquake. Firstly, a right frustum frame is selected as the basic geometric configuration for optimization (with the cuboid being a particular case of the frustum). Six critical design parameters serve as variables for optimization, establishing a mathematical model. Secondly, to maximize the permissible impact loads in both vertical and horizontal directions (F1 and F2), a multi-objective optimization using the NSGA-II algorithm is performed on the selected parameters, resulting in a Pareto front. Furthermore, to choose a solution from the Pareto front that meets the needs of this study, the relationship between the forces F1 and F2 applied to the shelter frame by falling debris during an earthquake is examined, converting the multi-objective optimization problem into a single-objective optimization problem. Finally, based on the relationship between F1 and F2, a single-objective optimization function is established and solved using the Genetic Algorithm (GA) to obtain the optimal parameters. The shelter frame manufactured with these optimal parameters exhibits better overall impact resistance than the cubic frame. This improvement is attributed not only to the geometric properties of the frustum, which results in a lower centre of gravity, but also to the optimization method, which enhances the frame's vertical impact resistance while maintaining good horizontal impact resistance.

Ensuring durability and reliability of contact rings of current collection devices when working in elastic-plastic state

The reliability of ring current-collecting devices during a given service life plays a decisive role in the opera- tion of power supply systems of various equipment and largely depends on the strength and reliability of all its components, in particular, contact rings. One of the most important characteristics of ring current collectors is the contact resistance, which is reduced by using non-ferrous and precious materials with low resistance, while increasing the downforce between the rings of the current collector. With an increase in the compression force F of the contact ring, the resistance of the contacts decreases to a certain minimum value and practically does not decrease with further growth of the force. The dependence of the contact resistance on the compression force has the form of a power function, the coefficients of which are determined experimentally. However, the operability of the contact rings in such severe conditions can be ensured in the case of low speeds and a small number of loading cycles by using the low-cycle fatigue area on the Weller curve. Having determined the coefficients of the equation of the inclined section on the Weller curve in the area of low-cycle fatigue, it is possible to determine the number of permissible loading cycles at a given stress level or solve the inverse problem of determining the permissible stress level if the number of loading cycles is known. To substantiate the correctness of the selected compressive force and the corresponding stresses, methods for calculating the fatigue margin coefficient, as well as a method for calculating the reliability of the ring material, are proposed. Reliability is estimated by the Gauss curve and is numerically expressed in the form of the probability of failure-free operation and the probability of failure, for which the corre- sponding theoretical dependencies are obtained. According to the proposed methods, calculations of the rings of the current-collection device used in EX- PRESS-type spacecraft were performed, which showed the operability of the methods and allowed to ensure the required service life of the contact rings and their reliability. A very simple analytical formulation of the methods allows us to solve both verification and design calculations of rings, depending on the task at hand.

Geoecological monitoring during mining operations

In recent decades environmental quality assessment has become a fundamentally important task in the operation of mining enterprises. This assessment becomes an integral part of the strategy for determining maximum permissible loads for mining regions and is aimed at reducing geoecological risk in them. Technological processes of mining and processing plants generate emissions of various pollutants into the atmospheric air, lead to violation of adjacent territories. Monitoring, primarily of atmospheric air and soils, is necessary to ensure the ecological balance of such territories. Lebedinsky Mining and Processing Plant is one of the most significant sources of gas and dust emissions from massive explosions in quarries during ore extraction, which form a large dust and gas cloud, creating a risk of deterioration of the life of the population in the surrounding area. The article examines the main pollutants in soils and in the atmospheric air during mass explosions, and determines the areole of their distribution from the work site. The forecast of an increase in the concentrations of detected harmful substances for the next 50 years is given. A methodology for conducting geoecological monitoring during mining operations is proposed. The research results may be useful in assessing geoecological risks and developing measures to reduce them.

Expansion of the range of permissible loads of a marine four-stroke diesel engine when using an adjustable turbocharger nozzle apparatus

The paper analyses the influence of the adjustable turbocharger nozzle apparatus on the parameters and criteria determining the thermal and mechanical stress of the main marine four-stroke diesel engine. The methodology of construction of limiting characteristics of mechanical and thermal stress using approximation dependences of parameters and criteria obtained by calculation-theoretical method is developed. The main parameters limiting the range of maximum permissible diesel engine loads on mechanical and thermal stress in the initial variant and in the variant with adjustable nozzle apparatus are revealed. It is established that the increase in the angle of rotation of blades of the adjustable nozzle apparatus up to the maximum permissible value causes a decrease in the parameters of thermal stress, as a result of which the zone of maximum permissible modes of operation of the diesel engine expands. At the same time, the parameters and criteria determining the mechanical stress of the diesel engine increase, but the reduction of the zone of maximum permissible loads on mechanical stress does not reduce the range of maximum permissible loads established by changing the thermal stress parameters.

ECOLOGIZATION OF TOURISM AS A COMPONENT OF THE CONCEPT OF SUSTAINABLE DEVELOPMENT

Topicality. The ecologization of production processes and the transfer of the entire system of economic reproduction of humanity to the principles that meet the objectives of environmental protection are an important condition for sustainable development. The strategy of sustainable development is one of the key and priority in all branches of industry, national economy and economics. Its principles and main provisions are aimed at achieving harmony between the growth of economic indicators, stability in the social sphere and environmental protection. Preservation of natural resources, maintenance of their sustainability and the transition to resource-saving, energy-efficient technologies is almost one of the key tasks on the agenda Aim and tasks. The purpose of the work is the analysis of the basic theoretical provisions of the concept of "ecologization of tourism" and the development of its directions. Materials and Methods. Calculation and compliance with the norm of permissible tourist load on the territory involves the normalization of loads based on quantitative indicators as one of the methods of ecologically-oriented management of the development of tourist activity. Reserch results. Within the framework of the conducted research, we consider it expedient to single out the main directions of ecologization of the tourism sphere at two levels: the first - measures directly related to the implementation of ecological principles in the tourism sphere; the second level does not directly concern the tourism industry, but in general promotes the implementation of the ecological trend in the development of the tourism industry. Conclusion. It is worth noting that the implementation of the areas of ecologization proposed in the work will contribute to the sustainable development of tourism, thanks to which it is possible not only to reduce the negative impact of tourism on the environment, but also to increase the level of ecological safety of the territories, as well as to more effectively implement the strategy of sustainable development.

Ecological assessment of pastures semi-deserts and dry steppes of Azerbaijan

The absence in the scientific literature of criteria for assessing the ecological status of pasture lands, insufficient knowledge of the use of predictive methods and technology for carrying out special agrochemical measures, as well as issues of permissible loads, served as the basis for choosing the topic of research work. For the first time, in the conditions of pastures in Azerbaijan, an environmental and energy assessment of soil-landscape complexes was carried out. A detailed and final quality assessment was drawn up on soil scale, and the coefficient of their comparative merit was determined. A scientifically based system of agrochemical measures for the superficial and fundamental improvement of pastures has been developed. The final bonitet scale, reflecting the level of fertility of soil varieties, showed that the soils of the Jeyranchol massif turned out to be the most fertile at 62 points, compared with them, the pasture soils of Ajinohur on average across the massif received 53 points, Gobustan 51 points, and the Kura-Araz lowland 55 points. On average, pasture lands in Azerbaijan are valued at 55 points, which indicates the need for agro-reclamation measures. The types of forage plants are distributed as follows: i) Cereals 116, 12%; ii) Asteraceae 109, 11.2%; iii) Legumes 82, 8.4%; iv) Brassicas 59, 6.2%; 6%; v) Cloves 50, 5.3%; vi) Lamiaceae 42, 4.6%; vii) Linear 40, 4.2%; viii) Goosefoot 6, ix) Gimletaceae 32 species, 3.4%; x) Umbrellas 38, 4.4%; xi) Other 339 types, 35.5%.

Determination of stresses in dangerous cross-sections of frame spars of minitractor vehicles

Problem. On the basis of the method of initial parameters, it is necessary to determine the mass-dimensional parameters of the frame of the spar type, for the creation of a universal small-sized vehicle UMTZ-26 "Nadia", as well as for the development of a mini-truck of category N1, with a carrying capacity of up to 3.2 tons. Goal. To determine the value of the maximum forces (stresses) and moments acting in the structural elements of the spar frame during the arrangement of the engine with transmission, body, engine compartment and cabin of the UMTZ-26 "Nadia" light vehicle, as well as units and aggregates of the N1 category, which can be used for municipal city or farm purpose. Results. According to the given calculation using the method of initial parameters (for frame structures), the maximum load in the cross section of the selected channel is determined, which does not exceed 106.372 MPa, the latter is used as a spar in the welded frame of the vehicle. The maximum permissible load that this profile of the channel can withstand is 160 MPa. Originality. The drawing and design documentation of the spar type was developed, which was used for the development of new universal small-sized vehicles of the UMTZ-26 "Nadia" type, as well as for the creation of mini trucks of the N1 category. Practical value. The practical value lies in the fact that the values of the maximum forces and moments acting in the side members of the frame when the engine with transmission, the engine compartment and the cabin of the vehicle are arranged on it do not exceed the maximum permissible values and the latter can be used on mini motor vehicles of category N1.

Reliability analysis of steel truss bars with imprecise statistical data

The article describes the probabilistic approach of reliability analysis for steel truss bars with imprecise statistical data. An approach to recovery the probability density of a random variable by the kernel density estimation method is illustrated for a small number of tests/measurements cases. The estimation of the distribution density parameters is presented in an interval form, which makes it possible to form a p-box for the random variable. Evaluation of the probability of non-failure allow to get a quantitative assessment for the safety of steel trusses, to identify the most unreliable trusses for monitoring their technical condition or to calculate the effect of strengthening the truss according to the reliability criterion. The probability of non-failure is estimated in the interval form. If the lower limit of the interval does not allow to get a conclusion about the truss safety level, then it can be increased by obtaining additional statistical data or by strengthening the truss or reducing the permissible load.

A new protocol to evaluate the behaviour and durability of marine structures

Sustained mechanical and environmental loadings on offshore structures result in creep phenomena. Creep and relaxation significantly affects the development of strains and stresses, thus they influence the durability of structures. Creep originates from the behaviour of the phases within the cement matrix. Seawater modifies the phases composition of cement matrix because of the variety of ions and their possible interactions with cement hydration products. This, in turn, affects the mechanical behaviour of structures, including creep. For durability and safety purposes, the design of offshore structures should consider the possible coupling between cement hydration, seawater exposure, and creep. Therefore, there was a need to develop a new protocol to evaluate the behaviour and durability of marine structures. As part of this new protocol, a new rig has been developed to evaluate the creep of cement-based materials immersed in seawater. The obtained results show that the short-term creep of structures in seawater is faster than in tap water. In the long term, even though multiple phases are microscopically formed due to seawater attack, the positive and negative effects of these phases formation and dissolution lead to almost similar creep development in seawater. This protocol can be used to assess the chemo-mechanical durability of multiple structural materials in order to develop low carbon materials. Additionally, it could improve the design of offshores structures by estimating the maximum permissible load based on the rigidity of structures and their chemical degradation level.

Buoyancy effect dualism on drill string axial forces calculation

This paper discusses the use of two buoyancy schools in determining the axial forces in the drill string, which leads to the duality of the solution. The difference in the results in determining the true and effective force and their relationship with each other using the strength of stability were revealed. It is shown that only the true force can be used to calculate the stresses and deformations of the drill string elements, since their actual values correspond to this force. At the same time, taking into account the effective forces, it is possible to more fully use the actual stability of the drill string, increasing the permissible loads on the bit and increasing the penetration rate. Thus, the presence of two buoyancy schools and, accordingly, two types of axial forces, makes it possible to more accurately and comprehensively assess the operability of the drill string.

РЕСУРСБЕРЕЖЕНИЕ В СИСТЕМЕ УСЛУГ СЕРВИСНОЙ КАСТОМИЗАЦИИ ТРАНСПОРТНО-ТЕХНОЛОГИЧЕСКИХ МАШИН

Transport and technological facilities operated in conditions of fulfilling the versatile tasks of the agro-industrial complex operate in constantly changing road conditions. These factors create problems for the stable operation of all machine systems, which generally requires adjusting the strategy for assessing their residual resource. Designers of transport and technological machines offer new models equipped with security systems, with a given reliability according to the criterion of criticality. Such systems are equipped with protective devices capable of withstanding a limited number of permissible external loads. (Research purpose) The research purpose is substantiating the individualization of the architecture of constructive customization of technological machines operated in the agro-industrial complex at the sites of service organizations that have undergone reengineering of production and technical infrastructure. (Materials and methods) Considered ways to improve agricultural machinery by manufacturers to increase their competitiveness. The problem of replacing machines that have exhausted their service life with new, structurally improved ones was highlighted. In an evidentiary form, it was shown that some of the components have a residual resource and the ability to continue to function effectively. (Results and discussion) It was proposed to use the resource reserves of the machines by justifying the extension of their service life. Recommendations were made for operators on the individualization of the architecture of constructive customization of technological machines operated in the agro-industrial complex. It is proposed to introduce innovative technological processes of machine modernization into the organizational structure of service organizations by reengineering the production and technical infrastructure. It was recommended to compare the time periods of technological progress when assessing the level of technical perfection of machines. As an example, a modal analysis of the undercarriage of technological machines was performed. (Conclusions) The resource-saving effect of the introduction of the service organization’s reengineering methodology with the inclusion of a model of customization of agricultural machinery with the justification of the service life extension period was substantiated.

Шумовое загрязнение территории многоэтажных жилых застроек города Ставрополя

The article provides measurement results and an assessment of the noise load on the territory of the «Perspektivny» and «Rossiysky» residential complexes in Stavropol. Noise measurements were carried out in the spring-summer and autumn-winter periods of 2022–2023. The measurement results are presented as average noise exposure levels. Based on the data obtained, a mathematical model of the propagation of noise from traffic flow during the deciduous and leafless period was built. To conduct a study and assess the noise load in a multistorey building on the territory of the South-Western district of Stavropol. The measurement of the noise load was carried out in accordance with GOST 23337-2014 “Noise. Methods for measuring noise in residential areas and in residential and public buildings”. To analyze and compare the data obtained with the maximum permissible value, SanPiN 1.2.3685-21 “Hygienic standards and requirements for ensuring the safety and (or) harmlessness of environmental factors for humans” was used. The measurement results revealed excess of maximum permissible noise level on the territory of the residential complex «Perspektivny» and «Rossiysky», and the houses within the residential complex «Perspektivny» suffer most from the proximity of the roadway and the absence or partial landscaping. Noise values were recorded near residential buildings in the range of 70 dBA. On the territory of the residential complex “Rossiysky”, high indicators are found on the sidewalk near the South-Western bypass. No excess of maximum permissible noise load level was noticed directly at the houses. The resulting mathematical model reflects the dependence of the noise level on the presence and absence of foliage and the density of traffic flow. Based on the data obtained, we can conclude that the residential complexes «Perspektivny» and «Rossiysky» are subject to significant noise pollution. This can be attributed to shortcomings in the planning of territory development and the increase in the number of vehicles.

Terminological clarification of the concept of truck overload

The article analyzes the concept of overload in relation to freight vehicles in conditions of weight control of vehicles. Based on the results of the analysis of a number of publications in this area, including scientific ones, it is indicated that the term "overload" used in them is identified with exceeding the normatively established permissible mass and (or) loads on the axles of the vehicle, which, in the reasonable opinion of the author, is incorrect. Based on knowledge in the field of terminology theory and guided by existing dictionary definitions of overload in railway and maritime transport, it is proposed to give the term "overload" in truck transport a similar meaning. Keywords freight vehicles, weight control, standard road loads, overload, vehicle axle loads, transport terms