Impact action of a projectiles on special protective structures and ways to increase their protective capacity

2021 ◽  
pp. 95-100
Author(s):  
A. Andrukhiv ◽  
A. Baranov ◽  
N. Huzyk ◽  
B. Sokil ◽  
M. Sokil
Keyword(s):  
Soil Layer ◽  
Strength Characteristics ◽  
Protective Structure ◽  
Impact Action ◽  
Dirac Delta ◽  
Wood Flooring ◽  
Protective Element ◽  
Applied Forces ◽  
Protective Structures ◽  
Elastic Elements

A method for studying the reaction of elastic elements of protective structures to a series of impact actions of shells has been developed. In the work, the elastic elements of the protective structure are modeled by homogeneous beams, and the dynamic action of the shells is simulated by instantaneous point-applied forces. A mathematical model of this dynamic process is constructed, which is a boundary value problem for a hyperbolic equation with an irregular right-hand side. The latter is described using Dirac delta functions. Cases of both fixed and free ends of protective elements are considered. The main ideas of perturbation methods are used for the researches carried out in the work. Analytical dependences for the description of elastic deformations of a protective element which are basic for definition of its strength characteristics are received. They and the graphical dependences built on their basis for specific cases show that the dynamic deformations of the protective element for the fixed ends are greater in the case of the projectile closer to its middle, at the same time for the free ends – closer to the end. With regard to the modernization of protective structures, the dynamic effect on their elements can be reduced by using elastic reinforcement or changing the method of fixing the ends of the protective element: elastic or with a certain angle of inclination of the bearing surfaces. It is proposed to use special plastics, soil layer, flexible wood flooring, etc. as elastic reinforcement. The technique used in the work is the basis for determining the strength characteristics of protective elements, and from so – to check the reliability of the protective structure; study of the dynamics of protective and similar types of structures, taking into account the nonlinear characteristics of the elastic elements of protective structures; study of more complex oscillations of elements of protective structures. In the case of a series of impacts, it is obvious that the amplitude of deflection of the protective element after each impact will increase over time, because the model does not take into account the force of viscoelastic friction. These tasks will be the subject of further research.

scholarly journals On ways to increase protection of special structures from impact action

2021 ◽  
pp. 52-57
Author(s):  
Andriy Andrukhiv ◽  
Andriy Baranov ◽  
Nadiia Huzyk ◽  
Bohdan Sokil ◽  
Mariia Sokil
Keyword(s):  
Mechanical Characteristics ◽  
Dynamic Effect ◽  
External Action ◽  
Engineering Structures ◽  
Discrete Function ◽  
Impact Action ◽  
Protective Element ◽  
Protective Structures ◽  
The Impact ◽  
Physical And Mechanical Characteristics

The technique of research of dynamic processes of elements of engineering constructions of special purpose from explosive action of projectiles is developed. Elastically reinforced beams with hinged ends were chosen for the physical model of elements of engineering structures. It is assumed that the elastic properties of the latter satisfy the nonlinear technical law of elasticity. A mathematical model of the process of a series of impact actions of projectiles at different points of the element of the protective structure is constructed. The latter is a boundary value problem for a partial differential equation. Its peculiarity is that the external dynamic action is a discrete function of linear and time variables. To determine the dynamic effect of a series of impacts on the object under study, and thus the level of protection of the structure, the basic ideas of perturbation theory methods are extended to new classes of systems. This allowed to obtain an analytical dependence of the deformation of the elastically reinforced element on the basic physical and mechanical characteristics of the material of the protective element, its reinforcement and the characteristics of the external action of the projectiles. It is shown that the most dangerous cases, given the security of the structure, are those when the impact is repeated at equal intervals, in addition, the point of impact is closer to the middle of the protective element. The obtained theoretical results can be the basis for selection at the stage of designing the main physical and mechanical characteristics of the elements of engineering structures and their reinforcement in order to reliably protect personnel and equipment from the maximum possible impact on it of the shock series of projectiles. The reliability of the obtained results is confirmed by: a) generalization of widely tested methods to new classes of dynamical systems; b) obtaining in the limit case the consequences known in scientific sources concerning the linearly elastic characteristics of the elements of protective structures; c) their consistency with the essence of the physical process itself, which is considered in the work.

scholarly journals NDT Methods Suitable for Evaluation the Condition of Military Fortification Construction in the Field

2020 ◽  
Vol 10 (22) ◽  
pp. 8161
Author(s):  
Zezulová Eva ◽  
Hasilová Kamila ◽  
Komárková Tereza ◽  
Stoniš Patrik ◽  
Štoller Jiří ◽  
...  
Keyword(s):  
Residual Strength ◽  
Fiber Reinforced Concrete ◽  
Protective Structure ◽  
Steel Fiber Reinforced Concrete ◽  
Degree Of Damage ◽  
Materials Used ◽  
Protective Structures ◽  
The Impact ◽  
Non Destructive

The protective structure is designed to protect the live force against the impact of a shock wave and projectiles, it cannot be diagnosed by the destructive method which devalues the protective structure by sampling. The authors are looking for a combination of suitable non-destructive technology (NDT) methods that would be used in the future to prove the degree of damage to cement-based protective structures after an explosion. This article represents the first part of an experiment designed to verify the applicability of NDT methods, to evaluate the degree of damage of the protective structure in the field. The experiment consists of three parts. The first part is a laboratory verification of the initial material characteristics of the materials used. The first test set of structural elements is made of steel fiber-reinforced concrete. The elements are evaluated using NDT methods and for comparison by destructive laboratory methods. The second part is the impact of structures using explosion and evaluation of the condition of structures using NDT methods in the field. The last part is used to verify the results of the NDT method, which ensures the residual strength of the structure in the laboratory and try to find the relationship between changes in the results of NDT methods and the residual strength. Radiography was included in the introductory and concluding parts of the experiment to verify the results. Although this method is not suitable for using in-situ, it is the only standardized method of the NDT methods used.

Research on Protective Performance of Protective Liquid Tank to Shock Wave Generated by Fragment

2020 ◽  
Author(s):  
Yang Hong ◽  
Xiaobin Li ◽  
Yuchen Bao
Keyword(s):  
Shock Wave ◽  
Simulation Method ◽  
Metal Plate ◽  
Protective Effects ◽  
Protective Structure ◽  
Finite Element Software ◽  
Metal Plates ◽  
Basic Parameters ◽  
Protective Structures ◽  
Pressure Changes

Abstract In this paper, the simulation method is used to study the installation of metal plates in the liquid tank as a protective structure. The process of shock wave propagation in the liquid tank is analyzed by finite element software, and the metal plate deformation caused by shock wave is discussed. In addition, the pressure changes of different measuring points are compared when installing aluminum plate, steel plate and no protective structure in the liquid tank, and the effects of different protective structures on weakening shock wave are analyzed. Through the simulation method, the protective effects of the three basic parameters (the layer number, position and angle) of the protective structure are analyzed, and the effects of different forms of protective structures on the ability for weakening shock wave are also discussed. The results of this paper can provide references for the optimal design of liquid tank protection and its application in ship protection.

scholarly journals Design and numerical assessment of a rapid-construction corrugated steel-concrete-steel protective structure

2019 ◽  
Vol 10 (4) ◽  
pp. 470-485 ◽  
Author(s):  
Sangwoo Jeon ◽  
Samuel Edward Rigby
Keyword(s):  
Numerical Study ◽  
Near Field ◽  
Steel Structure ◽  
Steel Structures ◽  
Cost Effective ◽  
Protective Structure ◽  
Rapid Construction ◽  
Numerical Assessment ◽  
Protective Structures ◽  
Harmful Effects

A protective structure should be sufficiently resilient to protect its occupants from the harmful effects of an impact or explosion. In many instances, protective structures are also required to be assembled quickly, and be cost-effective. Steel-concrete-steel (SCS) sandwich structures combine the benefits of steel; ductility and anti-scabbing, and concrete; energy absorption and rigidity. Despite these favourable characteristics, the performance of profiled-plate steel-concrete-steel structures under blast and impact loads has yet to be studied in detail. This article presents the results from a numerical study investigating the efficacy of a newly proposed profiled-plate arched steel-concrete-steel structure under the loading from an extremely near-field high explosive detonation. It is observed that as arch thickness (concrete infill depth) increases, a greater proportion of energy is absorbed through concrete crushing and a larger concrete mass is mobilised. It is shown that a 240 mm arch thickness is adequate to resist the blast load from a 5.76 kg TNT charge, therefore proving the suitability of the proposed protective structure.

ESTIMATION OF STABILITY OF LATERAL ROCKS IN A COAL MASSIF WITH INTRODUCE DEFORMATION CHARACTERISTICS OF PROTECTIVE CONSTRUCTIONS

2021 ◽  
pp. 64-74
Author(s):  
Leonid Bachurin ◽  
◽  
Ihor Iordanov ◽  
Olha Kohtieva ◽  
Vitaliy Dovgal ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Deformation Modulus ◽  
Bending Stiffness ◽  
Practical Significance ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Protective Structure ◽  
The Stability ◽  
Protective Structures ◽  
Supporting Structures

Purpose. Evaluate the stability of lateral rocks in the coal massif containing the workings, with introduce count the deformation characteristics of security structures. Methods. To achieve this goal, laboratory studies of the deformation characteristics of security structures located between the simulated roof and the sole of the coal seam, which were subjected to uniaxial compression. Results. It is proved that the deformation characteristics of protective structures affect the stability of lateral rocks in the coal massif containing the workings. The nature of the deformation of security structures under the action of external forces is determined by their rigidity. All other things being equal, when the roof and sole rocks have a constant bending stiffness, their stability depends on the rigidity of the supporting structures and the direction of the load applied in the tangential (wooden cogs, rolling cogs) or radial (riser bushes) direction. For the simulated security structures with an increase in the compressive load, a simultaneous linear increase in their stiffness and deformation modulus is recorded. Moreover, for wooden pillars, when the load is applied across the fibers, the clamped struts of wooden structures are compacted, as a result of which the convergence of the lateral rocks is limited. There is no such pattern for rigid structures in the form of bushes made of wooden risers. After the loss of stability of the protective structure, the modulus of deformation decreases, which is accompanied by an increase in the convergence of the side rocks to the complete destruction of the structure. It is recommended to abandon the rigid and at the same time fragile protective structures designed to support the side rocks. Scientific novelty. The stability of the roof in the carbonaceous massif containing the workings is estimated by the maximum relative deformation of the supporting structures as a result of uniaxial compression using a coefficient characterizing the ratio of the rigidity of the working protective structure and bending stiffness of the side rocks. Practical significance. To ensure the stability of the side rocks in the coal massif and the operational condition of the workings adjacent to the clearing face at the extraction site of the coal mine, it is necessary to focus on the use of flexible structures.

Research of Interaction of Landslide Soil with Protective Constructions of Support of Platforms

10.12737/341 ◽  
2013 ◽  
Vol 1 (1) ◽  
pp. 49-53
Author(s):  
Сергей Маций ◽  
Sergey Maciy ◽  
Дарья Лейер
Keyword(s):  
Finite Elements ◽  
Laboratory Testing ◽  
Structure Calculation ◽  
Calculation Scheme ◽  
Soil Deformation ◽  
Protective Structure ◽  
Proper Place ◽  
Loamy Soil ◽  
Straight Line ◽  
Protective Structures

Designing protective structures for trestle bents from deformations caused by landslides faces the problem of proper place- ment of pile elements. For developing effective landslide barriers for every single trestle bent, the calculation scheme is being proposed. It simulates interaction between landslide soil and the piles of straight line protective structure. Calculation scheme carried out using finite-elements method with geotechnical software Plaxis. In the process of analyzing the interaction between landslide’s loamy soil (with low strength characteristics) and single protective structure some of the most distinctive relationships were estimated: graphical characte­ristics of soil deformation in dependence from pile space and loa­ded force and also relationships between limited soil displacement as well as landslide pressure and structure’s configuration. The achieved results were compared with the ones from laboratory testing. Effective placement of pile elements in single protective structures was estimated on the basis of complex analyzing.

scholarly journals Fitting and testing roll-over protective structures on self-propelled agricultural machinery

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Domenico Pessina ◽  
Davide Facchinetti
Keyword(s):  
Lateral Stability ◽  
Protective Structure ◽  
Agricultural Machinery ◽  
Protection Level ◽  
Centre Of Gravity ◽  
Real Risk ◽  
Mass Dimension ◽  
Different Dimensions ◽  
Protective Structures ◽  
State Of Art

Roll-Over Protective Structure (ROPS) represents the state of art for the driver’s protection in case of tractors roll-over. Despite their real risk of overturning, the ROPS approach for the Self-Propelled agricultural Machinery (SPM) is quite recent. Due to the several SPM categories available on the market, characterized by very different mass, dimension and working functions, the fitting of a ROPS and consequently the ascertainment of its protection level is quite complicated. SPM could be preliminarily divided into at least two categories: - large SPM: combine, forage, potato, sugar-beet and grape harvesters; sprayer; etc.; - small SPM: ride-on tractor, mower, comb side-delivery rake, etc. The most followed approach at present is to check preliminarily the overturning behavior of the SPM considering its longitudinal and lateral stability; if a real risk of overturning is ascertained, in order to minimize the likelihood of driver’s injury the manufacturer often installs a ROPS. The consequent need is to provide some test criteria of them. Sprayers between large SPM, and comb side-delivery rake between small SPM were the machine types on which ROPS were tested, adopting in both cases the procedure provided by Code 4 issued by the Organization for Economic and Cooperation Development (OECD), dedicated to ROPS fitted on conventional agricultural and forestry tractors. Notwithstanding the very different dimensions of these two SPM, this standard was selected considering the predictable roll-over behavior, also in relation with the front and rear track values. On the 4950 kg mass sprayer was fitted a closed cab, while on the 690 kg mass comb side-delivery rakes a 3-pillars frame was applied. In both cases the response of the tests was positive, so indicating a general suitability of OECD Code 4 to assure a ROPS good driver’s protection level in case of overturning. On the other hand, to ascertain more in detail the roll-over behavior of the SPM, some further questions need to be deeply examined, such as the driver’s place location, the height of the centre of gravity from the ground in different machine configurations (i.e. with crop tanks empty or full), the external silhouette, the axles mass distribution of the laden/unladen machine, etc.

scholarly journals The Effect of Friction on Actuation Torques of Foldable Rollover Protective Structures

2018 ◽  
Vol 24 (4) ◽  
pp. 227-242 ◽  
Author(s):  
Farzaneh Khorsandi ◽  
Paul D. Ayers
Keyword(s):  
Friction Force ◽  
Dynamic Method ◽  
Protective Structure ◽  
Kinetic Friction ◽  
Safety Standards ◽  
Before And After ◽  
Protective Structures

Abstract. The number of fatal tractor rollover accidents with an inoperative foldable rollover protective structure (FROPS) has increased sharply in recent years. Operators frequently leave the FROPS in the folded-down position after lowering the FROPS to pass a low overhead obstacle. One possible explanation for leaving the FROPS in the folded position is that raising and lowering the FROPS is a time-consuming and strenuous process. The actuation torques required to raise and lower a FROPS are not well known and may be influenced by friction. The actuation torques of ten FROPS from four different models were measured. One model FROPS was tested on seven different vehicles, and three models were tested separately. The dynamic and static (initiation and holding) actuation torques were measured to evaluate the effect of static and kinetic friction on actuation torque. The dynamic actuation torques were measured before and after greasing the FROPS. The proposed instruction to measure the actuation torque based on OECD Code 7 was evaluated. Results showed that friction has a significant effect on the measured actuation torque and can increase the actuation torque by up to 212%. The friction varies between FROPS of the same model, which is due to variations in the manufacturing, maintenance, and age of the FROPS. The friction force could be decreased by greasing the FROPS, and decreasing the friction increased the lowering resisting torques and decreased raising torques of FROPS. The measured actuation torque based on OECD Code 7 instruction (static holding) is not a constant value. The dynamic method is recommended for measuring FROPS actuation torques. Keywords: Actuating torque, Foldable rollover protective structure, FROPS, Safety, Standards, Tractor.

The Operator Protective Structures Testing for Mining Machines

2010 ◽  
Vol 165 ◽  
pp. 256-261 ◽  
Author(s):  
Damian Derlukiewicz ◽  
Jacek Karliński ◽  
Artur Iluk
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Simulations ◽  
Computational Models ◽  
Experimental Tests ◽  
Passive Safety ◽  
Protective Structure ◽  
Simulation Results ◽  
Protective Structures ◽  
Element Method

The study presents selected problems concerning the testing of protective structures for the mining machines in the field of passive safety. Such machines equipped with protective structures must meet the requirements of the relevant regulations and standards. Requirements of conducting experimental tests of protective structures: FOPS, ROPS and RSPS are specified. The paper provides the principles of development of computational models for numerical simulations by means of finite element method. A detailed example of comparison of experimental and simulation results for a protective structure is presented.

scholarly journals Protected Culture for Vegetable and Small Fruit Crops: Types of Structures

EDIS ◽  
2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
Shinsuke Agehara ◽  
Gary Edward Vallad ◽  
Emmanuel A. Torres-Quezada
Keyword(s):  
Production Systems ◽  
Protective Structure ◽  
Fruit Crops ◽  
High Quality ◽  
Previous Version ◽  
Small Fruit ◽  
Minor Revision ◽  
Protective Structures

A protective structure is defined as any structure designed to modify the environment in which plants are grown. Protective structures, such as greenhouses, screen houses, and tunnels, are known worldwide as production systems for high-quality vegetable and fruit crops.  This minor revision by Shinsuke Agehara adds updated information regarding 2015 revisions to the Worker Protection Standards in the last paragraph, and removes one former author no longer affiliated with UF.https://edis.ifas.ufl.edu/hs1224 Previous version: Santos, Bielinski, Gary Vallad, and Emmanuel Torres-Quezada. 2013. “Protected Culture for Vegetable and Small Fruit Crops: Types of Structures”. EDIS 2013 (7). https://journals.flvc.org/edis/article/view/121080.

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