Acta Mechanica Slovaca, 2018 (vol. 22), issue 2
Key areas of research at the Department of Production TechnologyEditorial, Editorial article
Peter Demeč
Acta Mechanica Slovaca 2018, 22(2):4-5 | DOI: 10.21496/ams.2018.010 
Manufacturing machines and devices are involved in creating virtually every product. The main developmental trends in machine tool construction stem from customers' demands to shorten the production process in all its phases. For the machine tools design, this is an increasing demand for machine dynamics while maintaining their high working accuracy, flexibility and machine re-configurability based on modularity principles. Are being sought a new kinematic structures of machines, light and rigid constructions of moving machine nodes. Considerable time savings can be achieved at the development stage of the new machine by eliminating the need to manufacture...
Ultrasonic Quasi-Rayleigh Waves - Propagation Properties and Detection of Mechanical Damage
Michal Hlavatý, Miloš Musil, Branislav Hučko
Acta Mechanica Slovaca 2018, 22(2):6-15 | DOI: 10.21496/ams.2018.011
This article examines the propagation of quasi-Rayleigh waves and their trial application to detect defects in plate structures. With their specific propagation properties, quasi-Rayleigh waves have the potential to extend the scope of conventional ultrasound defect detection methods. This would enable detection across longer distances and with higher sensitivity, with earlier identification of surface defects in plate structures as a result. The article contains a basic description of quasi-Rayleigh waves, together with their propagation properties, with respect to a particular isotropic material (steel). The propagation of quasi-Rayleigh waves is...
Estimation of Complexity of Field Contours of Layer Building with the Use of Cell Method of Determining the Fractal Dimension
Yaroslav Garashchenko
Acta Mechanica Slovaca 2018, 22(2):16-23 | DOI: 10.21496/ams.2018.012
The results of estimating the geometric complexity of contours in layered building of a product by additive manufacturing are presented. The contour complexity was evaluated on the basis of a statistical analysis of their fractal dimension obtained the cell method. To determine fractal dimension of the contour, measures commensurate with the geometric limitations of layered building were used. Such limitations exist because of layered building peculiarities and technological capabilities of used equipment. Software has been developed to implement a layer-by-layer analysis of the original triangulation 3D model. Approbation of the software was carried...
Heat Pump Application at Hydrogen Compression While using Metal Hydride Materials
Tomáš Brestovič, Natália Jasminská, Marián Lázár
Acta Mechanica Slovaca 2018, 22(2):24-29 | DOI: 10.21496/ams.2018.013
This paper discusses about the possibility of using a heat pump when compressing hydrogen with metal hydride materials. Hydrogen is absorbed into the alloy at low pressure and temperature. Increasing the temperature of the alloy by absorbed hydrogen results in a significant increase in pressure, with hydrogen desorption being carried out at an increased equilibrium pressure. A compressor working with MH materials requires cyclic heating of the reservoir from which hydrogen will be desorbed and absorbed.
The Possibility of Using Adhesive for Bonding Steel with Ceramics
Ivan Jandrlić, Stoja Rešković, Tin Brlić, Damir Hršak
Acta Mechanica Slovaca 2018, 22(2):30-33 | DOI: 10.21496/ams.2018.014
Nowadays many different systems use elements that are constructed from different materials. There are various solutions for joining different kinds of materials into one part. Whether we are talking about mechanical or adhesive bonding, both types of joints have their advantages and disadvantages. In certain cases, preference is given to the adhesive bonding. It is primarily from the inability of constructing a mechanical connection, or the possibility of cracking due to the technical nature of the mechanical joints. Such case occurred when a ceramic cylinder was needed to be connected to the metal spindle. This paper presents determination of the...
Measurement of Surface Roughness of Volleyball
Jan Dumek, Jan Urban
Acta Mechanica Slovaca 2018, 22(2):34-37 | DOI: 10.21496/ams.2018.015
Main investigations are focused to measurements of all forces and moments acting on the rotating volleyball, such as drag FD, lift FL, side force FS, moment of roll MX, pitch MY and yaw MZ. Based on previous first results roughness of surface is an important quantity to study. Description of measurement of surface roughness of volleyball is presented in the article. Devices used in the measurement are noted. Results of the measurement are discussed and meaning of the results for aerodynamic forces acting on volleyball is taken in consideration.
Development of Fuel Maps in Hexadecimal Format for Reduction of NOX Emissions and Application in Real HCCI Engine
Michal Puškár, Melichar Kopas, Dušan Puškár
Acta Mechanica Slovaca 2018, 22(2):38-47 | DOI: 10.21496/ams.2018.016
The newest generation of the electronic control systems, which are determined for the combustion engines, is characterised by a complex structure of the control algorithm. Modification of these systems is performed using a data field editing in order to reach the maximal output parameters. The active algorithms of the control units gained a remarkable participation and mutual relation. The control software is operating with the numerical combinations, which are described in a hexadecimal format. There were suggested various types of the fuel maps and they were tested by means of measurement realised during four sequences of a powerful engine. At the...
Heat loss Calculations of Underground Central Heating Pipelines
Pavel Sláma, Jiří Nožička
Acta Mechanica Slovaca 2018, 22(2):48-53 | DOI: 10.21496/ams.2018.017
The article subject is the experimental temperatures measurements on the thermal areas surrounding the preinsulated district heating pipes, located below the ground surface. The heating pipes are located in to the sand filling. The results of the mentioned experiment are applied for supplementation and modification proposals of the equations used for determination of the heat losses from the heat pipelines. The article copes with the thermal conductivity of the pipe insulation material in dependence on the temperature, the thermal conductivity of the non-homogeneous surrounding filling material in the space around the pipe and the periodic function...
Working Precision of the Machining Centre
Dominika Palaščáková, Peter Demeč
Acta Mechanica Slovaca 2018, 22(2):54-59 | DOI: 10.21496/ams.2018.018
The aim of the article is to analyse the precision of the machining centre using numerical and experimental quantification. The identification of the effects of the machining process itself as well as the impact of machine design features will allow it to predict and subsequently optimize its construction in terms of its working accuracy. Measurement of dynamic forces and geometric tolerances was also carried out. The practical importance of virtual machining is primarily the reduction of financial costs and acceleration of machine design without the need to produce a physical prototype. Using simulation models, it is possible to repeatedly analyse...