Actual number: 4/2020

ISSN 1339-5017 (Online)

Archive:


No. 3

SPECIAL OFF-ROAD VEHICLES - SELECTED CHARACTERISTICS

Author: Jiří STODOLA, Alena BREZNICKÁ, Jozef MAJERÍK, Miroslav ČERVENÝ

Abstract: Special off-road vehicles capable of use in difficult terrain conditions are employed in the military, agriculture, forestry, civil engineering, exploration and mining, earthworks, and other operations. Similar principles apply to all these vehicles in terms of the mechanics of movement and the interaction of the vehicle with the terrain. The authors deal only with selected problems including a brief passage about the mechanics of movement in the terrain, environment and its characteristics, obstacles, trafficability as well as the basics of autonomous vehicles.

Keywords: Off-road vehicle. Terrain characteristics. Trafficability. Autonomous vehicle.

Vol. 13, 2019, No. 3, p. 1-7

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METHODOLOGY FOR MEASURING AND ASSESSING STATIC CHARACTERISTICS OF LIQUID ELEMENTS

Author: Beáta KOPILÁRKOVÁ, Ján ZÁPOTOČNÝ, Maroš ECKERT

Abstract: The paper is focused on determination of static characteristics of elements used in hydraulic circuits. The elements for which the given characteristics are created are valves - safety and pressure control, hydraulic distributor and hydraulic generator. Measurements were performed at experimental stations and components created in the authors' workplaces. Wiring verification and hydraulic diagrams were created in FluidSIM Hydraulics simulation software. The methodology and method of obtaining characteristics of the type Δp = f (Q), i.e. the dependence between the pressure drop and the flow rate for given hydraulic elements described in this article, may be applicable to other elements creating local hydraulic resistances.

Keywords: Hydraulic. Pump. Valves. Pressure drop. Flow rate.

Vol. 13, 2019, No. 3, p. 8-15

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VIBRATION SMALL ARM BARREL

Author: Peter PERUN

Abstract: Muzzle vibration of small arm during shoot is caused by projectile motion in navigate part of small arm barrel. Amplitude of muzzle vibration depends on barrel material, barrel production technology, constructional solution of arm automatics, type and quality ammunition. Size variations muzzle at the moment of the shot directly affects the accuracy of fire.
By exchange of inside and outside barrel loading come to exchange of muzzle vibration magnitude during shoot. To small arm muzzle vibration detection was carried out the experiment by shooting. The weapon was loaded with shooting during which the size deflection of the small arm barrel was measured by the vibrodiagnostic device.
To small arm muzzle vibration detection was created model of small arm barrel with accessories in program LS-Dyna. Model of small arm barrel come out of proportions and material of small arm Sa vz.58. Barrel accessory creates front sight carrier and gas chamber. Both components represent addition mass to barrel without accessories, that are change muzzle oscillation character. Model of small arm barrel is loaded by inside forces affect during shoot. There are, press of burning powder gases and reaction of projectile moving in barrel.
Goal is comparison size deflection of muzzle small arm barrel model, versus size deflection of muzzle small arm barrel weapon Sa vz.58 from experiment.

Keywords: Barrel vibration. Muzzle. Small arms barrel model. Simulation.

Vol. 13, 2019, No. 3, p. 16-22

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BASIC MECHANICAL PROPERTIES INFLUENCED BY DRAWING TECHNOLOGY OF COPPER WIRES

Author: Jana KURICOVÁ, Marta KIANICOVÁ, Andrej DUBEC, Daniel KOTTFER, Petra KOVÁČIKOVÁ

Abstract: In the industrial field that manufactures products, which are used in electrical installations, copper is an essential
part in terms of the use of materials. Due to excellent electrical and thermal properties compared to other metallic
materials, copper is mainly used for the manufacture of electrical conductors of various cross-sections depending
on the area of application, from small electronics to high-voltage conductors. In the manufacturing process, copper
is subject to strict operating conditions, especially in terms of chemical purity, in order to ensure the required
mechanical and electrical properties. The copper conductors which are subject of this study are made by cold
drawing technology. In this production process, the input semi-finished product is a copper rod with a circular
cross-section. This copper rod is formed by various number of dies which ensure the final diameter of the wire.
The passage of wire through the individual dies during drawing has a disadvantageous influence and reveals an
uneven distribution of strain intensity for the drawn material and causes the changes of mechanical properties
along the wire cross-section [1]. Despite the various advantages of this manufacturing process, the drawing of
wires leads to a reduction in plasticity, especially in the case of multiple drawing. Wires lose their strength due to
the high presence of residual stresses that have arisen after pulling, which can negatively affect their function under
operating conditions [2]. The above mention structural and mechanical changes are the subject of this study. The
knowledge of this experiment can be beneficial for applications of mechanically loaded electrical conductors.

Keywords: Cold drawing. Mechanical properties. Copper wire. Reinforced structure. Tensile test.

Vol. 13, 2019, No. 3, p. 23-29

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IMPACT OF HARDNESS OF RUBBER COMPOUNDS ON TIRE WEAR

Author: Pavol MIKUŠ, Alexej CHOVANEC, Alena BREZNICKÁ, Igor BARÉNYI

Abstract: This article deals with the effect of mechanical properties of a compound on tire wear. For detection purposes the
samples of 13 kinds of rubber compounds were made, used and processed in practice. The hardness was measured
with durometer of IRHD (International Rubber Hardness Degrees) type; Rapid wear test was conducted on a roller
abrasive machine. All measurements were assessed and compared. The selected original results are listed in this
article.

Keywords: Tire. Wear. Hardness. Effect. Testing samples.

Vol. 13, 2019, No. 3, p. 30-34

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POLYMERIAL NANOCOMPOSITIONS

Author: Lenka BARTOŠOVÁ

Abstract: The constant increase in the production and consumption of polymer materials places increasing demands on
improving their processing and utility properties. In this respect, the dynamic development of nanotechnology, a
science that deals with behavior, properties, and the creation of structures with dimensions approaching atomic
size, is a great help. Polymer nanocomposites are nowadays among the highly developing materials. Significant
advances in this area are documented not only by the substantial increase in funding for nanocomposite research,
but also by the almost exponential increase in the number of scientific publications and patents observed in recent
years.
The result is new nanostructured materials, the building units of which are nanoparticles with defined structure
and properties. Today, not only polymer nanocomposites are known, but also metallic and ceramic
nanocomposites. While polymeric nanocomposites are gradually being used in industrial practice, metal and
ceramic nanocomposites have so far only been prepared under laboratory conditions.

Keywords: Nanocomposites. Nanofillers. Polymer. Structure. Carbon fibers.

Vol. 13, 2019, No. 3, p. 35-39

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PARAMETRIC MODEL OF THERMOELECTRIC GENERATOR

Author: Milan JUS, Jiří BALLA

Abstract: The paper presents the creation of a parametric model and simulation of a thermoelectric generator (TEG), which
should be supplemented by a photovoltaic panel. Such a modification should be used in an Grid-Off system.

Keywords: Thermoelectric effect. Thermoelectric generator. Seebeck effect. Composite material. Multilayer
material.

Vol. 13, 2019, No. 3, p. 40-45

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PROGRESS OF THE WHEELED AND TRACKED UNMANNED GROUND VEHICLES

Author: Miroslava CÚTTOVÁ, Peter DROPPA, Vladimír POPARDOVSKÝ, Eva POPARDOVSKÁ,
Štěpán PAVLOV

Abstract: The article deals with the analysis of the current state of the advancement in the area of the unmanned ground
vehicles (UGVs) at home and abroad. Currently, the army programs are focused on the development of UGVs in
the three areas - light, medium and heavy ground vehicles. Each category has different main aim. The light vehicle
can provide reconnaissance in urban environments. The heavy vehicles will be support the forces with the weapon
systems to engage and destroy the enemy. The multifunction vehicle is vehicle medium size. Based on the obtained
data, the concept of the wheeled and tracked unmanned ground vehicle was realized. This vehicle could be used
in conditions of the Slovak republic.

Keywords: Unmanned ground vehicle. Wheeled vehicle. Tracked vehicle. Advancement.

Vol. 13, 2019, No. 3, p. 46-53

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