Actual number: 4/2020

ISSN 1339-5017 (Online)

Archive:


No. 2

QUASI-STATIC NANOINDENTATION STUDY OF PHERITE-MARTENSITE DUAL PHASE STEEL

Author: Igor BARÉNYI, Jozef MAJERÍK

Abstract: The paper of authors deals with the quasi static nanoindentation technique of the DP 600 steel. It is dual phase steel consists of martensite and ferite. The phases have different mechanical properties where their optimal combination gives benefit final mechanical properties of the steel. Nanoindentation testing is a method that consists essentially of touching the material of interest whose local mechanical properties as are hardness and elastic modulus are unknown. Nanoindentation testing is simply an indentation test in which the length scale of the penetration is measured in nanometres (10-9 m) rather than microns (10-6 m) or millimetres (10-3 m), the latter being common in conventional hardness tests. Both load and depth of penetration are recorded at each load increment (ultimately providing a measure of modulus and hardness as a function of depth beneath the surface). The presented paper also quantifies the difference in hardness and elastic modulus of both present phases.

Keywords: quasi-static nanoindentation, TI 950triboindenter, dual phase steel, scanning probe microscopy.

Vol. 12, 2018, No. 2, p. 1-5

Initiates file downloadDownload PDF

TRIBOLOGICAL CHARAKTERISTICS OF POLYMER MATERIALS

Author: Lenka BARTOŠOVÁ

Abstract: The paper deals with the tribological properties of selected polymeric materials. It communicates with particular selected polymers and their slip properties. It also describes the Tribolab tribological device and the test methodology. In the end, it evaluates the measured values and possibilities of using selected polymeric materials in practice.

Keywords: Tribology, friction, polymer, measurement, friction coefficient.

Vol. 12, 2018, No. 2, p. 6-9

Initiates file downloadDownload PDF

MIXING OF AMMUNTION AND EXPLOSIVES IN STORAGE

Author: Alena BREZNICKÁ

Abstract: Ammunition and explosives of different hazard divisions may be stored together if compatible. The required quantity-distances and the permitted quantities must be determined in accordance with from the security principles for the storage of military ammunition and explosives AASTP-II.

Keywords: Military ammunition, explosives, different hazard divisions.

Vol. 12, 2018, No. 2, p. 10-13

Initiates file downloadDownload PDF

SIMULATION ALGORITHM OF A SUPPLYING PROCESS WITH A VARIABLE TIME STEP

Author: Alena Breznická, Alexej Chovanec

Abstract: This technique bootraping has been successfully used in various applied statistical problems, although not many applications have been reported in the area of time series. In this paper we present a new application of Bootstrap to time series. A fundamental aspect of supply chain management is accurate demand forecasting. We address the problem of forecasting intermittent (or irregular) demand, i.e. random demand with a large proportion of zero values. Items of spare parts with sporadic consumption can make a significant, up to 60% portion of the value of supplies in service and workshop inventory areas of many industrial segments. An understanding of key features of demand data is important when developing computer systems for forecasting and inventory control.

Keywords: Simulation algorithm, supplying process, simulation modelling variable time step, sporadic demand

Vol. 12, 2018, No. 2, p. 14-17

Initiates file downloadDownload PDF

SIMULATION MODEL OF A SPORADIC DEMAND

Author: Alexej Chovanec, Alena Breznická

Abstract: This technique bootraping has been successfully used in various applied statistical problems, although not many applications have been reported in the area of time series. In this paper we present a new application of Bootstrap to time series. A fundamental aspect of supply chain management is accurate demand forecasting. We address the problem of forecasting intermittent (or irregular) demand, i.e. random demand with a large proportion of zero values. Items of spare parts with sporadic consumption can make a significant, up to 60% portion of the value of supplies in service and workshop inventory areas of many industrial segments. An understanding of key features of demand data is important when developing computer systems for forecasting and inventory control.

Keywords: Simulation modelling, sporadic demand, bootstrapping, forecasting

Vol. 12, 2018, No. 2, p. 18-22

Initiates file downloadDownload PDF

EFFECT OF MATERIAL FRICTION BALL ON COEFFICIENT OF FRICTION STEEL E335

Author: Michal KRBAŤA, Maroš ECKERT

Abstract: This work examines the influence of the ball of the material on the friction coefficient of the selected sample. AISI 1010 steel beads, AISI 420 / C stainless steel, polypropylene and ZrO2 were selected for the experiment. A sample of E335 was selected as the sample material according to EN 10025. The friction coefficient was measured using the "Ball on disk" method. The device parameters were set to three radii of 18, 20 and 22 mm, after which the ball of the selected material rotated. Measurement was performed at room temperature 23 ° C and lasted 4 min. The load parameter was selected at 10 N. Finally, metallographic analysis of the sample was carried out, and Vickers hardness was also measured to determine the effect of the hardness of the bead material on the resulting coefficient of friction.

Keywords: coefficient of friction, ball, steel, tribology, microhardness

Vol. 12, 2018, No. 2, p. 23-27

Initiates file downloadDownload PDF

METHODOLOGY FOR COMPUTATION OF INTRABALLISTIC PARAMETERS AND A RESISTANCE PRESSURE

Author: Peter LIPTÁK, Ivan KOPECKÝ

Abstract: Please take into consideration the fact that the full text of an abstract should contain no more than 1000-2000 characters (including spaces). In the abstract provide information on how the objectives were achieved, which was the main method(s) used, what was the approach to the topic etc. Please provide information on the main conclusions. What are the suggestions for a future research? What practical implications are identified? 

Keywords: Thermodynamic interior ballistic model, ammunition, weapon system, aimed at a detailed solution of energy losses.

Vol. 12, 2018, No. 2, p. 28-37

Initiates file downloadDownload PDF

HIGH-ENERGETIC MATERIALS AS A PRECONDITION TO PROLONG A LIFETIME OF EXPLOSIVES

Author: Peter LIPTÁK, Ivan KOPECKÝ

Abstract: High-energetic materials involve operations with special equipment. An application of new non-traditional materials – composites and nano-materials makes this field highly up-to-date and from a research point of view it is needed to pay attention to it. The paper presents current characteristics of such materials, their classification and supposed trends of their development.

Research in the field of high- energetic materials makes a mutual progress conditional on mechanical and electrical engineering, which includes special equipment. The paper also deals with issue of mutual interaction of weapon and ammunition systems containing energetic materials. Work with high-energetic materials is not only a part of work for defence industry as well as a part of work in crisis management, mining, building and other parts of the life of a society.

Keywords: High-energetic materials, explosives, special equipment, nano-materials, composites, crisis management.

Vol. 12, 2018, No. 2, p. 38-43

Initiates file downloadDownload PDF

HAZARD CLASSES OF AMMUNITION AND EXPLOSIVES AND THEIR CHARACTERISTICS

Author: Štefan PIVKO

Abstract: In order to promote the safe storage and transport of dangerous goods, an International System for Classification has been devised. The system consits of 9 classes (1-9) of which Class 1 comprises ammunition and explosives. Class 1 is divided into divisions. The hazard division indicates the type of hazard to be expected primarily in the event of an accident: mass explosion (Division 1.1), projection effects (Division 1.2), fire and radiant heat (Division 1.3), no significant hazard (Division 1.4), mass detonation with very low probability of initiation (Division 1.5) and detonation of a single article, with low probability of initiation (Division 1.6). Ammunition and explosives must be classified in accordance with STANAG 4123. National authorities competent for the classification of ammunition and explosives are given in AASTP-3.

Keywords: Transport, hazard division, classification code.

Vol. 12, 2018, No. 2, p. 44-46

Initiates file downloadDownload PDF