Acta Mechanica Slovaca, 2011 (vol. 15), issue 3
Analysis of Causes Unwanted Dynamical Phenomenon on Output Pipes of Turbocompessor
František Trebuňa, Róbert Huňady, Miroslav Pástor, Michal Binda
Acta Mechanica Slovaca 2011, 15(3):6-13 | DOI: 10.21496/ams.2011.022 
During their operation the pipes of gas compressor stations are influenced by dynamic impacts caused by operating equipments as well as flowing media. Due to the occurrence of excessive vibrations on output pipes of turbocompressor after its modernisation, experimental vibration analysis of the output pipe of turbocompressors was realized, which included experimental modal analysis and vibration measurements during operating of turbocompressors.
Outline of FEM Simulation and Modelling of Hard Turning Process
Ildiko Maňková, Pavel Kovac, János Kundrak, Jozef Beňo
Acta Mechanica Slovaca 2011, 15(3):14-21 | DOI: 10.21496/ams.2011.023
Hard machining, as attractive replacement for many rough and finish grinding operation, generates high cutting forces and temperature that enhance tool wear when act together. Therefore, the tool geometry and machining parameters have to be carefully optimized for a given material. Because of high cost and time consuming experimental work up-to-date advanced software for modeling and simulation brings quick and adequate solution. The aim of this contribution is to study the influence of cutting parameters and material hardness on accompanying phenomena when hard turning process with mixed oxide ceramic inserts. Hardened steel with different hardness...
Research of Selected Acoustic Descriptors of Two-Layer Sandwich Absorbers
Miroslav Badida, Ladislav Bartko, Ervin Lumnitzer, Róbert Szabó
Acta Mechanica Slovaca 2011, 15(3):22-29 | DOI: 10.21496/ams.2011.024
In spite of existing European and national legislation aimed at noise abatement, public interest and concern about noise are high. The EU Directive 70/157/EEC [13] for setting and controlling environmental noise is aimed at creating less noisy and more pleasant environment for European residents within "Sustainable Development in Europe". The authors are presenting a methodology for measuring selected acoustic descriptors (sound absorption coefficient and sound transmission loss) for acoustic materials, which are currently in process of development. Emphasis is put on sandwich structures of absorbers. Verification results of the proposed methodology...
Application of Fast Multipole Boundary Method in Elastostatic Problems
Milan Žmindák, Pavol Novák, Daniel Riecky
Acta Mechanica Slovaca 2011, 15(3):30-37 | DOI: 10.21496/ams.2011.025
The boundary element method (BEM) is a numerical method for solving boundary-value or initial-value problems formulated by use of boundary integral equations. In the BEM, only the boundaries - that is, surfaces for three-dimensional problems or curves for two dimensional (2D) problems - of a problem domain need to be discretized. However the boundary element method (BEM) has been limited to solving problems with a few thousand degrees of freedom (DOFs) on a personal computer. This is because the conventional BEM, in general, produces dense and nonsymmetric matrices. The main idea of the fast multipole (FM) BEM is to employ iterative solvers to solve...
Application of Inverse Vibration Problems to Model Updating
Ladislav Starek, D.J. Inman, Daniel Starek
Acta Mechanica Slovaca 2011, 15(3):38-45 | DOI: 10.21496/ams.2011.026
This paper summarize the authors previous effort on inverse eigenvalue problem and applies the theory to the model updating problem. Comments are made on how their procedure may be used to solve the damage detection problem.
Tensile Tests of Flat Bars at High Strain Rate
Ivo Dohnal, Miroslav Šlais, Milan Forejt, Radko Smek
Acta Mechanica Slovaca 2011, 15(3):46-51 | DOI: 10.21496/ams.2011.027
Plastic deformation of metallic materials and alloys is a complex process that depends on a number of factors with the effect of strain rate being of particular importance. Dynamical tests are used for determination of mechanical properties. Split Hopkinson Pressure Bar Test is often used for these experiments. The paper deals with possibilities of testing device for flat bars adapted at Hopkinson test. The aim of this work is concentrated on strain rate influence on DC 01 steel too.
Analysis of Water Pollution Indicators with the Use of Selected Statistical Methods
Miriam Andrejiová, Zuzana Kimáková, Dušan Knežo
Acta Mechanica Slovaca 2011, 15(3):52-61 | DOI: 10.21496/ams.2011.028
The need to protect the environment from pollution is still one of the most important issues in modern world. It is generally accepted that the environment covers a broad scale of elements; including air, water, soil, flora and fauna, as well as human health and security, and these are to be protected which is a part of global goal to ensure permanent and sustainable development.Water is the basic substance and condition of human life on Earth. Until recently it has been possible to satisfy humans' requirements for water without any greater difficulties and that is thanks to regenerative and self-cleaning ability of water. The development of industries,...
Cyclic Calculation of Inverse Kinematics for n-link Serial Mechanism
František Trebuňa, Zdenko Bobovský
Acta Mechanica Slovaca 2011, 15(3):62-67 | DOI: 10.21496/ams.2011.029
Inverse kinematics of mechanic system is area of solution at many universities and scientific research institutions. This paper dealt with of solution problem of inverse kinematic by a cyclic coordinate descent method (CCD). This method allows use n-link chain mechanism without complicated changing of control algorithm. The article is focuses on the issue of setting the number of elements and also presents a modified method the incremental CCD, which is compared with this method.
Mathematical Model of Fatigue for Steel Wire Ropes
Dušan Knežo
Acta Mechanica Slovaca 2011, 15(3):68-71 | DOI: 10.21496/ams.2011.030
The steel wire rope is stressed during operation by the tensile and bending forces. This loading state has a relevant impact on mechanical characteristics of the rope. A negative influence on the rope properties has a corrosion of the rope wires, especially. The wires are the basic construction components of the rope. It is necessary to know changes of rope mechanical characteristics with regard to a safety and reliability of the rope operation. In a case that the rope properties are not able to fulfil requirements of the safety and reliability, it is unavoidable to put-off such rope. There is presented in this paper a mathematical model describing...
Experimental Investigations on Cavitation in a Kaplan Turbine
Mouleeswaran Senthil Kumar, S. Chidambara Raja, M. N. Sarath Kumar
Acta Mechanica Slovaca 2011, 15(3):72-78 | DOI: 10.21496/ams.2011.031
An experimental investigation has been carried out in order to evaluate the detection of cavitation in Kaplan turbine. The methodology is based on the analysis of structural vibrations and sound level measured in the turbine. The proposed techniques have been checked in horizontal dispositioned Kaplan turbine suffering from different types of cavitation. Although cavitation within pumps has been the subject of extensive research up to now, as demonstrated by the works from [1], [2], [3], [4] and others, it must be noted that few studies have been published related to cavitation within hydropower turbines. Because of that, the current paper is mainly...
Selection of Wood Waste Chipper Drive Located on Automobile Chassis
Jaroslav Homišin
Acta Mechanica Slovaca 2011, 15(3):80-86 | DOI: 10.21496/ams.2011.032
The aim of every designer is to reduce the size of torsional vibration in any mechanical system. Successful control of torsional vibration can be achieved only if a detailed analysis, computation of system in terms of torsional dynamics. The test results indicate that the intended objective can be achieved only if, some members of the system parameters are properly adapted to the dynamics of the system itself. This means that any torsionally oscillating mechanical system should be properly tuned. Therefore, the aim of Article will be to present and confirm an appropriate choice of wood waste chipper drive located on the automobile chassis based on...
Verification of the Effect of Temperature and Duration of Stamina for Heat Treatment of Zinc Coating on the Formability of Procedural AHSS Steels
Slavomír Pavelčák, Emil Spišák, Attila Herditzky, Peter Svantner
Acta Mechanica Slovaca 2011, 15(3):88-93 | DOI: 10.21496/ams.2011.033
Subject of presented contribution is process formability parameters evaluation of both side coated TRIP and HSLA steels in basic state and after its annealing in order to Fe-Zn coating creation. The samples were annealed at 450, 500 and 550°C for 10 and 60 seconds in argon shielding gas. Obtained values are compared with each other in order to determine whether the influence of temperature and duration after annealing changed the original class inclusion on a scale to measure the quality of steel sheets for deep drawing according to the value of limit drawing ratio. Limit drawing ratio was used as a process formability criterion and were reached by...