Communications - Scientific Letters of the University of Zilina, 2000 (vol. 2), issue 3
Articles
Experimental investigation of the strength of anisotropic solids under biaxial loading oblique to the principal material directions
Josef Eberhardsteiner, Manfred Gingerl, Lubomir Ondris, Rudolf Beer
Communications - Scientific Letters of the University of Zilina 2000, 2(3):4-7 | DOI: 10.26552/com.C.2000.3.4-7 
Realistic finite element ultimate load analyses of structural details as well as of shell structures made of anisotropic materials require suitable constitutive equations for the prediction of the deformational behavior and ultimate strength of biaxially loaded solids. However, there is a lack of adequate biaxial experimental data, particularly if loading situations are considered where the principal loading directions do not coincide with the principal material directions. From the theoretical point of view one has to obey the stress-strain relationship. There is no principal difference in dealing with different kinds of anisotropic materials, such...
Metallothermy in the cast iron "out of the furnace treatment "process
Stanislaw Borkowski
Communications - Scientific Letters of the University of Zilina 2000, 2(3):8-14 | DOI: 10.26552/com.C.2000.3.8-14
Production of high-quality cast irons in a batch production is topical current problem. Existing technologies of melting cast iron are not very progressive. The basic theoretical knowledges of obtaining of alloyed cast iron (Cr, Ti) by using metalothermy are presented in this work. The oxides are sources of this elements. The metalothermy treatment process is running without decrease of liquid metal temperature, comes to increase of quantity addition elements and reduction of quantity of carbon and sulphur.
Heat distribution when titanium alloy vt9 grinding
Dusan Steklac, Miroslav Neslusan
Communications - Scientific Letters of the University of Zilina 2000, 2(3):15-19 | DOI: 10.26552/com.C.2000.3.15-19
Heat distribution in machining is one of phenomenological characteristics of this process because it significantly influences functional properties of machined surfaces. The paper deals with heat distribution in the cutting zone when grinding titanium alloy VT9 based on experimental measurement of surface temperature and tangential component of cutting force. Heat distribution when grinding titanium alloy VT9 differs from heat distribution when grinding conventional roll bearing steel 14 209.4 as a typical representative of ground hardened steels first of all because of low heat conductivity of titanium alloys.
A new method for durability dependance of a cutting tool on a cutting speed
Karol Vasilko
Communications - Scientific Letters of the University of Zilina 2000, 2(3):20-29 | DOI: 10.26552/com.C.2000.3.20-29
In the entire history of the development of the metal cutting theory Taylor's whhich appeared in 1905, has been used to describe the relation between a cutting tool durability and a cutting speed. This relation was established in 1905. This work presents the analysis of the up to now attempts carried out to improve the mentioned relation. The submitted proposal results in the method of creation of the Tvrelation, which provides a much better identity with the experiment. In the second part of the work the method is verified experimentally on aseries of experimental results.
Contribution of modelling to the optimization of forming and heat treatment of structural steels
Jaroslav Koutsky
Communications - Scientific Letters of the University of Zilina 2000, 2(3):30-35 | DOI: 10.26552/com.C.2000.3.30-35
New laboratory of technological processes modelling, equipped with two Silicon Graphic Indigo R 5000 stations, one 500au DEC OSF/1 station with software systems Forge 2D and 3D, Hypermesh, Systus and Sysweld, was built up at the Department of Material Science and Technology at WBU Plzeň. Some research projects aimed at the modelling and optimization of technological processes, e. g. simulation of cold deformation influence on the structure of P900 steel, or simulation of free forging of shafts manufactured from CrMo steel were carried out. Partial results give a good agreement between experimental results and simulation.
A contribution to the optimization of wear behaviour of steel used for railway wheels
Werner Mombrei, Peter Ottlinger
Communications - Scientific Letters of the University of Zilina 2000, 2(3):36-38 | DOI: 10.26552/com.C.2000.3.36-38
In the next chapter the paper deals with the influences in the state of heat treatment of the wheel steel related both to the wear resistance and to the reason of the runout.
Flux coating enhanced absorption of al surfaces at the characteristic wavelength of co2 laser irradiation
Janos Takacs, Peter Gal, Antal Lovas, Joachim Belt
Communications - Scientific Letters of the University of Zilina 2000, 2(3):39-43 | DOI: 10.26552/com.C.2000.3.39-43
Aluminium brazing is a method for joining Al-parts in close proximity by introducing liquid alloys which melt above 577 °C. On the basis of an applied heat source, conventional (flame) and energy-beam brazing (laser) can be distinguished. The laser is capable to result in rapid local melting around the surface to be joined. In spite of the high energy density (represented by laser irradiation) the melting of Al is often unsuccessful. The reason is the low absorption ability of Al at around the wavelength characteristic to the CO2 laser. Coatings with a high absorption ability have to be used in order to facilitate the energy absorption. In the present...
The rheological properties of cement pastes containing fly ash with different particle size distribution
Stefania Greszczyk, Grzegorz Lipowski
Communications - Scientific Letters of the University of Zilina 2000, 2(3):44-47 | DOI: 10.26552/com.C.2000.3.44-47
The paper presents the analysis of fly ash influence on rheological properties of cement pastes with content different type of fly ash concerning particle size distribution. It was pointed that rheological properties of cement pastes containing fly ash from bituminous coal (hard coal) depend mostly on content fly ash in cement and on the quantity of fine fraction in fly ash as well as on the shape of fly ash particle.
Model of earthen foundation with reinforcement in a deep excavation
Andrzej Surowiecki, Zenon Zamiar
Communications - Scientific Letters of the University of Zilina 2000, 2(3):48-51 | DOI: 10.26552/com.C.2000.3.48-51
In this paper, the results of model investigation of strength characteristics are discussed for the case of horizontally reinforced loose soil medium. The characteristics are then employed to create a model with vertical reinforcement. The vertical reinforcement has been proposed for the model of earthen foundation in a deep excavation whose bottom is subjected to displacement.
Independent formation of longitudinal forces in bent beams
Sylwester Kobielak, Grzegorz Troszczynski
Communications - Scientific Letters of the University of Zilina 2000, 2(3):52-61 | DOI: 10.26552/com.C.2000.3.52-61
This paper deals with the phenomenon of horizontal constraints being strutted by bent beams. This phenomenon takes place when rotating ends of beam sections encounter the resistance of horizontal constraints. Consequently, reactions occur between the constraints and the beam horizontal which induce a longitudinal compression force. Equations for two load cases: a uniformly distributed and concentrated force applied to the span centre, allowing to determine the value of this force and its influence on deflection and load capacity on the on the basis of the linear and non-linear theory were derived. The analysis carried out on this base showed an advantageous...