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1
Content available Comparison of low and high frequency fatigue tests
Vasko A., Belan J., Kucharikova L.
Production Engineering Archives
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2017
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Vol. 17
15--18
EN
The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100; high frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both fatigue tests were realised at sinusoidal cyclic push-pull loading (stress ratio R = –1) at ambient temperature (T = 20 ± 5 °C).
2
Content available A brief overview and metallography for commonly used materials in aero jet engine construction
Belan J., Vasko A., Kucharikova L.
Production Engineering Archives
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2017
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Vol. 17
9--14
EN
Aluminium, titanium, and nickel base alloys are mostly and widely used for aircraft jet engine construction. A proper evaluation of its microstructure is important from working safety point of view. To receive a well prepared sample of microstructure, some important steps have to be undertaken. Except for proper grinding and polishing of a sample, structure developing is a significant step, too. In order to develop microstructure various chemical reagents were used to achieve the best results for microstructure evaluation. The chemical reagents were used according to the previous knowledge and some new ones were also tested. Aluminium AK4-1č, titanium VT – 8, and nickel VŽL – 14 and ŽS6 – U alloys were used as an experimental materials. Alloy AK4-1č is used for fan blade production with working temperatures up to 300°C. It is a forged piece of metal machined down into final shape by five-axe milling machine. Alloy VT – 8 is used for high pressure compressor rotor blade production with working temperatures up to 500°C. Blades are forged as well and finally grinded. Finally nickel base alloys VŽL – 14 and ŽS6 – U are used for turbine blade production with working temperatures up 950°C. Blades for turbine are casted into mould with reducible models.
3
Content available Numerical methods for analysis of mechanical systems with uncertain parameters
Vasko M., Saga M., Vasko A.
Production Engineering Archives
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2016
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Vol. 11, No. 2
18--21
EN
The paper presents new and improved numerical methods designed for analysis of mechanical systems with uncertain parameters. Uncertain parameters in mechanical systems are described using possibility theory. The main representatives of this theory are fuzzy and interval numbers. Algorithms using interval and fuzzy numbers are incorporated into the analysis. The possibilities and efficiency of suggested methods and algorithms are tested by programs created in the environment of the software package MATLAB.
4
Content available Employing various metallography methods at high temperature alloy fatigue tests evaluation
Belan J., Kucharikova L., Vasko A., Chalupova M., Svecova I.
Production Engineering Archives
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2016
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Vol. 13, No. 4
11--15
EN
Microstructures of superalloys have dramatically changed throughout the years, as modern technology of its casting or forging has become more sophisticated. The first superalloys have polyedric microstructure consisting of gamma solid solution, some fraction of gamma prime and of course grain boundaries. As demands on higher performance of aero jet engine increases, the changes in superalloys micro-structure become more significant. A further step in microstructure evolution was directionally solidified alloys with columnar gamma prime particles. The latest microstructures are mostly monocrystalline, oriented in [001] direction of FCC gamma matrix. All microstructure changes bring necessity of proper preparation and evaluation of microstructure. Except for the already mentioned structures have gamma double prime and various carbides form can be seen. These structural parameters have mainly positive influence on important mechanical properties of superalloys. The paper deals with a microstructural evaluation of both groups of alloys – cast and as well as wrought. Micro-structure evaluation helps to describe mechanism at various loading and failure of progressive superalloys. Such an example where micro-structure evaluation is employed is fractography of failure surfaces after fatigue tests, which are examples of metallography evaluation de-scribed in this paper as a secondary objective.
5
Content available Correlation between shape factor and mechanical properties of graphitic cast irons
Vasko A., Vasko M.
Production Engineering Archives
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2016
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Vol. 11, No. 2
11--14
6
Content available The micro-mechanisms of failure of nodular cast iron
Vasko A., Chalupova M.
Production Engineering Archives
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2014
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Vol. 5, No. 4
31--35
EN
The contribution deals with a comparison of the micro-mechanisms of failure of nodular cast irons at static, impact and fatigue stress. Several specimens of ferrite-pearlitic nodular cast irons with different content of ferrite in a matrix were used for metallographic analysis, mechanical tests and micro-fractographic analysis. Mechanical properties were found by static tensile test, impact bending test and fatigue tests. The micro-fractographic analysis was made with use of scanning electron microscope VEGA II LMU on fracture surfaces of the specimens fractured by these mechanical and fatigue tests. Fracture surfaces of analysed specimens are characteristic of mixed mode of fracture. Micro-mechanism of failure of nodular cast irons is dependent on the method of stress.
7
Content available Controlling of the logistic processes
Ulewicz R., Vasko A., Klimecka-Tatar D.
Production Engineering Archives
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2014
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Vol. 3, No. 2
26--30
EN
The paper presents analysis of the controlling application in logistic processes in the foundry of the cast iron. Controlling of quality was introduced in order to raise efficiency of the foundry of the cast iron management. A comparative method was applied to examinations. Two spheres were compared to managing of the organization: managing the quality by the sphere with the zone of management with finances. The purpose of this action is finding common features when supervising tasks in both these zones.
8
Content available remote Applications of methods of quantitative metallography in materials engineering
Vasko A., Belan J.
International Journal of Applied Mechanics and Engineering
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2010
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Vol. 15, no 2
405-410
EN
The paper deals with the comparison of different methods of quantitative metallography, namely: the evaluation of the microstructure by etalons, measurement of structural parameters by coherent test grids and automatical image analysis. The advantages or disadvantages of individual methods are shown on the example of evaluation of the microstructure of graphitic cast irons, carbon steels, silumins and nickel superalloys.
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