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Experimental and Numerical Analysis of Eccentrically Loaded Beam-Columns

Author(s): Jozef Vican,Peter Janik,Ružica Nikolić / Language(s): English Issue: 4/2014

The beam-column subjected to the combination of the axial force and the bending moments is an example of the very complicated task from the viewpoint of the design resistance verification. The general theoretical solution of the resistance assessment of that beam-column is not suitable for practical use due to complicated and non-general form. Then, the standard simplified approach is used. Therefore, the paper deals with the experimental and numerical analyses of the resistances of eccentrically loaded beam-columns and their comparison with the standard approaches. Discussion of results and conclusions related to further research direction are also presented in this paper.

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Correlation of Water Absorption Values of Bitumen Waterproofing Sheets Obtained According to CSN EN 14223 and CSN 503602

Author(s): Jan Plachy,Jana Vysoka,Radek Vejmelka,Zdeněk Caha / Language(s): English Issue: 4/2014

The article deals with the issue of weight water absorption of bitumen waterproofing sheets. It compares two methodologies applicable to examination of water absorption of bitumen waterproofing sheets from the point of view of testing procedures. It compares the results of both the methods for individual bitumen sheets upon experimental measurement and examines mutual relation between the individual results. The experimental measurement was performed on bitumen sheets used for waterproofing of bridge deck [1].

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Groups with the Infinite Non-Quasicentral Nodal Subgroup

Author(s): Ludovit Tomanek,Anna Tomankova / Language(s): English Issue: 3/2014

We present some properties of the groups with the infinite non-quasicentral periodic nodal subgroup. Our main results are formulated in Theorem 1, 2 and Theorem 3, 4. 2000 Mathematics Subject Classification: 20F22, 20F25

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Monomial Curves in Afinne Space and their Associated Prime Ideals with Six Generators as Set-Theoretic Complete Intersections

Author(s): Michaela Holesova / Language(s): English Issue: 3/2014

The paper deals with the problem of the expression of associated prime ideals of monomial curves in the affine space A4 as set-theoretic complete intersections. We describe some associated prime ideals, a minimal generating set of which has six elements and we prove that these ideals are set-theoretic complete intersections. Corresponding monomial curves are intersections of three hypersurfaces and we find the equations of these hypersurfaces.

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Existence of Positive Solutions of a Nonlinear Differential Equation with N Delays

Author(s): Maria Kudelcikova / Language(s): English Issue: 3/2014

...Estimation of positive solutions is given as well. The proof is based on the retract technique.

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Reliability Analysis of Noncoherent Systems by Logical Differential Calculus and Binary Decision Diagrams

Author(s): Jozef Kostolny,Miroslav Kvassay,Stefan Kovalik / Language(s): English Issue: 1/2014

Reliability is the important characteristic of systems. Most of the systems consist of more than one component. Moreover, modern systems are very complex and they include a lot of components. Therefore, effective methods have to be developed for analysis of these systems. The techniques that have been already considered for this purpose are the Binary Decision Diagrams and the Logical Differential Calculus. However, these methods have been considered only for the coherent systems. In this paper, their use in the reliability analysis of the noncoherent systems is considered

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PDMS-Based Nanoimprint Lithography for Photonics

Author(s): Dusan Pudis,Daniel Jandura,Peter Gaso,Lubos Suslik,Pavol Hronec,Ivan Martincek,Jaroslav Kovac,Sofia Berezina / Language(s): English Issue: 1/2014

Implementation of planar surface photonic crystal (PhC) structures leads to improvement of optical properties of optoelectronic devices. Application of such structures can be attractive for overall and local enhancement of light from patterned areas of the light emitting diode surface and for lightwave-guiding devices. We present techniques useful for PhC patterning and for patterning of different optic structures in surface of new promising material polydimethylsiloxane (PDMS). Paper proposes nanoimprint technology for fabrication of PhC in the surface of thin PDMS membranes for possible application in light emitting diodes. By PDMS patterning and its positioning on the device surface one can achieve original optical properties of optoelectronic devices. We also present new technique for fabrication of surface-relief fiber Bragg grating (SR FBG) based on PDMS waveguide.

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Mobility of Multibody Systems in Terms of their Incorrectness

Author(s): Alzbeta Sapietova,Milan Saga,Alexandr Shimanovsky,Milan Sapieta / Language(s): English Issue: 3A/2014

The paper presents examples of incorrectness from the point of view of body and Multibody System (MBS) kinematics. This incorrectness should be kept in mind when modeling Virtual Prototypes (VP) of MBS. During the analysis or synthesis of MBS it is necessary to correctly determine the degree of freedom (DOF) of mechanisms in order to properly design the mechanism. The basic relation for the DOF computation does not include parameters such as special dimensions of links or their mutual configuration and geometric constraints. In many cases, these issues require individual approach, i.e. by analyzing the properties of incorrect MBS to identify the causes of their incorrectness and apply the computation method to the actual mobility. The paper contains samples to illustrate a particular topic.

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Mathematical Model for Prediction of Biomass Ash Melting Temperature using Additives

Author(s): Michal Holubcik,Jozef Jandacka / Language(s): English Issue: 3A/2014

Some types of biomass ash have low ash melting temperature which can result in various problems in combustion processes. Ash slags and sinters can avoid heat transfer in heat exchangers, which can also cause corrosion of heat transfer surfaces. One of the ways of burning fuels with low ash melting temperature is to use additives. Ash melting temperature can be determined in a laboratory on the basis of standard STN ISO 540. Meltability of ash is characterized by the physical state of ash occurring during the heating process under well-defined conditions in the furnace. Experimental determination of ash melting temperature is quite expensive. In this work a prediction method of ash melting temperature is described. The mathematical model uses multiple linear regression where input parameters are the known chemical composition of fuel ash and used additive converted to an amount of SiO2, CaO, K2O, MgO and Al2O3. The mathematical model is relatively accurate with real ash melting temperatures and reaches accuracy about of 90 % compared with ash melting temperatures obtained by STN ISO 540 method in a laboratory.

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The Structure and Mechanical Properties of Domex 700 MC Steel

Author(s): Magdalena Mazur,Robert Ulewicz,Frantisek Novy,Pawel Szataniak / Language(s): English Issue: 4/2013

Nowadays fine-grained, quench and tempered steels are more and more used in design of modern semitrailers constructions. High mechanical properties and durability of this type of steel are its advantage. This paper summarizes the results of research together with the data available by the manufacturer SSAB company. The combination of the special features provided by this material enables construction of lighter semitrailer's components, which would result in a semiauto with a lower weight of its own. This paper presents the results of mechanical properties of Domex 700 MC steel.

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Possibilities of Eliminating the Higher Amount of Iron in Secondary AlSi7Mg0.3 Alloy by Chrome

Author(s): Dana Bolibruchova,Lukas Richtarech,Wladyslaw Orlowicz / Language(s): English Issue: 3A/2014

This paper deals with influence on segregation of iron based phases by chrome. Iron is one of the most common impurities that could be found in Al-Si alloys. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition of some other elements that affect the segregation of intermetallics in less harmful type. Realization of experiments and results of analysis show new perspective on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases. It could be concluded that higher amount of chrome causes the formation of sludge particles.

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Simulation of Roundness, Hardness and Microstructure of Bearing Rings with Thin Cross Sections by Using Sysweld

Author(s): Peter Fabian,Peter Jankejech,Martina Kyselova / Language(s): English Issue: 3A/2014

The roller bearing is a component which helps to reduce friction on relative rotational or sliding movements of the machine parts. Nowadays, there are many kinds of rolling bearings whose production is constantly improving due to increasing demands on the mechanical properties and durability. An important and necessary step in the production of rolling bearings is the heat treatment. Technological heating process must be created rationally for the required mechanical properties such as hardness, toughness and also dimensional accuracy all with respect to the economic efficiency. Because of the economical demands, simulation software is increasingly beginning to be used in the projection of heat treatment. This simulation software can predict metallurgical and mechanical properties of components after heat treatment, and thus it is easier to select the optimal material design, heat treatment process and it can possibly identify construction deficiencies in the selected part. For simulation of the heat treatment the SWYSWELD software from ESI group was used. As the output value after the simulated heat treatment (quenching) was hardness, composition of microstructure, roundness and residual stresses. These results of the simulation were then compared with the real measured values [1, 2 and 3].

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Data Structures Implementation of the Protocol Step-NC at CNC Machines Programming

Author(s): Nadezda Cubonova,Ivan Kuric / Language(s): English Issue: 3A/2014

Standard STEP-NC (ISO 14649) presents a new model for data transmission between CAD/CAM systems and CNC machines. This standard eliminates the shortcomings of the standard G-code and provides new possibilities in their management. At the Department of Automation and Production Systems, Faculty of Mechanical Engineering, University of Zilina in the framework of the research activities was solved a project for the implementation options of STEP-NC format by programming of CNC machines. This paper presents the results of research solutions which focused mainly on the analysis of standard STEP-NC, a methodology on the model data according to the standard STEP-NC using the EXPRESS language as well as the creation of software for the transformation of STEP-NC data - „TERMINAL STEP NC“. The software has been verified in the transmission of STEP-NC data to a particular CNC machine control system. Transfer of STEP-NC data applications gives the possibility of verifying the implementation of the new standard in older types of CNC machines.

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Tension Mechanism Dynamic Analysis

Author(s): Michal Lukac,František Brumerčík,Leszek Krzywonos,Paweł Droździel / Language(s): English Issue: 3A/2014

The aim of the presented article is to show how to create a mathematical model of the tension mechanism working by a spring motion generation and contacting a rigid body at the end of the motion.

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Biodegradation Properties Of Az31 Magnesium Alloy Coated by Dicalcium Phosphate Dihydrate

Author(s): Filip Pastorek,Miroslav Omasta,Lenka Bukovinova,Pavel Dolezal,Branislav Hadzima / Language(s): English Issue: 3A/2014

Biodegradation properties of magnesium and its alloys that can be used for implants are not satisfactory and cause serious problems. These problems can be solved by biodegradable surface coatings. Evaluation of biodegradation process of Mg-3Al-1Zn alloy surfaces after grinding and grinding followed by potential controlled electrodeposition of dicalcium phosphate dihydrate (DCPD) was investigated by electrochemical impedance spectroscopy measurements in this study. The potentiostatic electrodeposition treatment process was performed in water solution of Ca(NO3 )2.4H2 O, NH4 H2 PO4 and H2 O2 . The corrosion process on treated and nontreated samples after various exposure times was evaluated in 0.9% NaCl solution simulating body fluid environment at 37 °C.

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Corrosion Properties of Various Copper Pipes Joints

Author(s): Tatiana Liptakova,Monika Halamova,Ayman Alaskari,Martin Lovisek,Maxim Puchnin / Language(s): English Issue: 3A/2014

The paper presents the experimental results of various Cu pipes joint corrosion behavior. Joining of copper pipes used for liquid media transport can be made as demountable and fixed joints. The object is to study corrosion resistance of the joints created by soft soldering, hard soldering and fitting. Corrosion properties were investigated by long-term experiment in two identical experimental devices in stagnant and flowing conditions. The experimental environment was water solution of the 3% NaCl, temperature was kept 20° C for 16 hours and 8 hours 80° C per day. In one of the devices for 8 hours the experimental solution was flowing by the input speed 0.27m.s -1. In the second one no flow was applied. Evaluation of the joints corrosion attacks was performed visually, by light and scanning electron microscopy.

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Influence of Tool-Workpiece Interface on Surface Integrity after Turning

Author(s): Jaroslav Dubec,Miroslav Neslusan,Anna Micietova,Maria Cillikova / Language(s): English Issue: 3A/2014

This paper deals with influence of flank wear on decomposition of cutting force in turning roll bearing steel. The decomposition is carried out to evaluate the components of cutting force in the tool-chip as well as tool-workpiece interface. The decomposition enables evaluation of the shear and normal forces in the both interfaces. The results of experiments and the following calculations show that while conditions for chip separation in the tool-chip interface stay nearly untouched due to progressive development of flank wear, mechanical load of machined surface associated with components of cutting forces progressively increases with flank wear. The paper also reports about influence of flank wear on surface integrity expressed in such parameters as residual stresses, surface topography, structure transformation and microhardness.

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Meshless Analysis of an Embankment Using Local Galerkin Radial Point Interpolation Method (LGRPIM)

Author(s): Juraj Muzik,Karel Kovarik,Dana Sitanyiova / Language(s): English Issue: 2/2013

The paper deals with use of the meshless method for slope stability analysis. There are many formulations of the meshless methods. The article presents the Local Galerkin Radial Point Interpolation method (LGRPIM) – local weak formulation of the equilibrium equations. The main difference between meshless methods and the conventional finite element method (FEM) is that meshless shape functions are constructed using randomly scattered set of points without any relation between points. The shape function construction is the crucial part of the meshless numerical analysis in the construction of shape functions. The article presents the radial point interpolation method (RPIM) for the shape functions construction. The numerical example of the slope stability was calculated using meshless computer code and compared with FEM results.

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Comments on the Power of Kolmogorov Test

Author(s): Andrzej Rogowski / Language(s): English Issue: 3/2013

This paper presents the results of estimating the power of Kolmogorov test and its modifications for testing hypothesis about an exponential distribution against the alternative hypothesis (population has a Weibull distribution). The power of test was calculated based on a distribution of empirical cumulative distribution function and limiting distribution, as well as computer-simulation methods. Some important properties and limitations were given that are related to power simulation study of goodness-of-fit tests.

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Behaviour and Strength of Headed Shear Stud Connectors

Author(s): Patricia Duratna,Jan Bujnak,Abdelhamid Bouchair,Frantisek Bahleda / Language(s): English Issue: 3/2013

Headed stud shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface in composite structures. This paper is focused on the experimental and numerical study on the behaviour of this type of connectors. The push-out tests of headed studs, 10 mm in diameter and 50 mm in length, in normal C25/30 concrete with transverse reinforcement were carried out. The experimental study also treated the influence of the connectors spacing, in the longitudinal and transversal directions, and the thickness of the concrete slab on the shear resistance.

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