Acta Mechanica Slovaca, 2014 (vol. 18), issue 3-4
Virtual Prototyping - advanced Instrument of Increasing the Quality of Machine Tools DesignEditorial, Editorial article
Peter Demeč
Acta Mechanica Slovaca 2014, 18(3):4
Mechanical Joining of Steel Sheets in Automotive Industry
Emil Spišák, Ľuboš Kaščák
Acta Mechanica Slovaca 2014, 18(3):6-12 | DOI: 10.21496/ams.2014.025 
Various ferrous and non-ferrous materials and their combinations are used in car body production in automotive industry. These materials need to fulfil several criteria before being approved. Some of the criteria are the results of regulation and legislation with the environmental and safety concerns and some are the requirements of the customers. In many occasions different factors are conflicting and therefore a successful design would only be possible through an optimized and balanced solution. The most commonly used method for joining the materials is resistance spot welding. Some materials or their combinations are very difficult or even impossible...
Proposal of Methodology and Calibration of Dynamometers for Quantification of Forces in Anchor Bolts
Miroslav Pástor, František Trebuňa, František Šimčák, Marián Buršák, Patrik Šarga, Ľubomír Gabáni
Acta Mechanica Slovaca 2014, 18(3):14-19 | DOI: 10.21496/ams.2014.026
Anchor bolts in heavy machines of metallurgical plants are often, from the point of view of their carrying capacity, limiting factor in increasing productivity. This paper presents some possibilities of increasing strength of anchor bolts using numerical and experimental methods of mechanics. Proposed and verified procedures allow determining the actual stress states during tightening the anchor bolts and nuts and reduce dynamic loads in bolts as well as in operating machines.
Evaluation of Friction Coefficient of Stamping
Emil Evin, Stanislav Németh, Marek Vyrostek
Acta Mechanica Slovaca 2014, 18(3):20-27 | DOI: 10.21496/ams.2014.027
This In order to define the friction coefficient the simulator of strip drawn test between flat dies and cup test were applied. To evaluate the coefficient between flat dies the modified Coulumb law was used and for defining the friction at drawing edge of die the modified Ouehler formula was applied. Due to these both evaluation processes it was enabled to point out the difference of friction coefficient values in various contact areas of rolling product and the tool. In his paper there are presented the measurement and evaluation processes of friction coefficient by applying the cup test. For experimental research the following types of materials...
Analysis of Combustion Noise in Diesel Engines
Sunny Narayan
Acta Mechanica Slovaca 2014, 18(3):28-34 | DOI: 10.21496/ams.2014.028
Injection process in diesel engines is a key to control engine performance parameters such as torque and power as well as to control noise and emissions from engine. Condition monitoring of injector is an important methodology for obtaining information about fuel injection process. However it is difficult to monitor the injector motion using air borne engine acoustic signals. In this work adaptive filtering has been used to study the injector impacts using condenser microphone located at a distance of 0.25 m from the engine rig on a array structure. The data obtained was filtered and processed in MATLAB 7 software. Various injection pressures were...
Verification of Safety of Containers for Spent Nuclear Fuel by Thermal and Pressure Tests
František Trebuňa, František Šimčák, Jozef Bocko, Miroslav Pástor, Peter Frankovský, Patrik Šarga
Acta Mechanica Slovaca 2014, 18(3):36-43 | DOI: 10.21496/ams.2014.029
During safety verification of containers for transport spent nuclear fuel is useful to use a combination of experimental and numerical methods of mechanics. According to present regulations, they have to comply with prescribed tests realized on real containers or their models that have the same basic properties as evaluated object. In the paper are given experimental as well as numerical treatments for safety verification of containers under thermal and pressure loading together with presentation of reached results.
Critical Aspects of the Cracked Brazilian-disc test Explored by the Method of Caustics
Stavros K. Kourkoulis
Acta Mechanica Slovaca 2014, 18(3):44-55 | DOI: 10.21496/ams.2014.030
Some critical aspects of the cracked Brazilian-disc test are explored in the light of recently introduced analytic solutions for the stress- and displacement-fields developed in a centrally cracked cylindrical disc under uniform pressure (acting along two finite arcs of its periphery symmetric with respect to the disc's center). The study is focused to the reliable determination of the respective Stress Intensity Factors (SIFs) and also to the role of the actual boundary conditions along the disc-jaw contact arc (assuming that the disc is compressed between the curved jaws of the device suggested by the International Society for Rock Mechanics (ISRM)...
Environmantal Ipact of Mining
Vojtech Dirner, Eliška Kulová, Kateřina Polínková
Acta Mechanica Slovaca 2014, 18(3):56-67 | DOI: 10.21496/ams.2014.031
This paper deals with the impact of mining on the environment. Coal mining is still among the most widespread and most intense mining activity, which disturbs the landscape around us. For many countries, including the Czech republic, deposits of raw materials play an important role, especially for purposes of producing electricity and thermal energy. Part sof these problem are: the monitoring, environmental impacts assesment of exploration and mining activities and waste disposal mining, which may significantly contribute to the environmental protection in the future.
Educational Model of Four Legged Robot
Alexander Gmiterko, Michal Kelemen, Ivan Virgala, Ľubica Miková
Acta Mechanica Slovaca 2014, 18(3):68-73 | DOI: 10.21496/ams.2014.032
The paper deals with four legged walking robot Youpy. The robot has been designed as educational model. It has 8 degree of freedom in legs. Control of locomotion is based on reposition of centre of gravity. Standard servomechanism is used as actuator, which is frequently used for radio controlled models. After the simulations realized on 3D model, the functional model has been constructed. Designed flowchart of the forward locomotion has been verified on functional model. Maximum velocity for forward locomotion is 25 cm/s. Next part of the paper deals with conception of the feedback control of legs motion.
Stress Analysis Performed in the Near Surrounding of Small Hole by a Digital Image Correlation Method
Martin Hagara, Róbert Huňady, František Trebuňa
Acta Mechanica Slovaca 2014, 18(3):74-81 | DOI: 10.21496/ams.2014.033
The paper deals with the description of the whole process of stress fields identification performed in the near surrounding of a small hole using digital image correlation. At first the authors simply describe the principles and possibilities of modern optical devices working on digital image correlation principle. After then they focus on the analysis of strain fields as well as investigation of the influence of some correlation parameters such as facet size, virtual grid, smoothing and size of the calibration target on the accuracy and quality of the obtained results. As the correlation systems usually serve only for strain analysis, the stress analysis...