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1
Únavové vlastnosti hořčíkové slitiny AZ31
Zapletal J., Gejdoš P., Podrábský T., Věchet S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2008
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z. 92
83-84
EN
Magnesium alloys are desirable for their low densities and high specific strength to structural use. That is why determining of fatigue properties magnesium alloys are desirable. Here was examined fatigue properties on squeeze casting magnesium alloy AZ31 with 0.5 wt% Ca.
2
Influence of homogenizing on structure and mechanical properties of AZ91 alloy
Němcová A., Zapletal J., Podrábský T., Provazníková A., Věchet S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2008
|
z. 92
77-78
EN
This paper deals with the influence of homogenizing on mechanical properties of magnesium alloy AZ91. The experimental material was made squeeze casting. Results of tensil test of the sample without heat treatment and samples with homogenizing (405°C/5, 10, 15 and 24 hours) were compared. To study of microstructure light microscopy was used.
3
Vliv rychlosti ochlazování a tepelného zpracování na mechanické vlastnosti hliníkové slitiny AlSi7Mg0,6
Zapletal J., Věchet S., Kohout J.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2007
|
Vol. 321, z. 89
51-52
EN
This article describes the influences of cooling speed and head treatment on the microstructure and mechanical properties of aluminium alloy AlSi7Mg0,6 (trade description – Anticorodal 72). Results of tensile test (strength, yield strength, ductility, etc. ) to both method heat processing (T6 and T 64).
4
Kvantitativní hodnocení degradace struktury niklových superslitin pomocí obrazové analýzy
Němec K., Podrábský T., Věchet S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2007
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Vol. 321, z. 89
35-35
EN
Nickel-base superalloys, strengthened by the ´ phase dispersion, presents the typical precipitation strengthened alloys. In creep testing conditions, particles of secondary phase can be effectively blocks of dislocations movement at high temperatures as well. However, particles must be sufficiently stable with respect to coalescence, it means the average distance between them increases very slowly during creep. The aim of this work is the study of structural changes of the material Inconel 7I3 LC by image analysis. It is focused on short-time creep tests at temperatures 850°C and 950°C.
5
Estimation of tolerance bands of S-N curve
Kohout J., Věchet S., Zapletal J.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2007
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Vol. 321, z. 89
29-30
EN
A precise determination of tolerance bands of S-N curves is very difficult problem; therefore simple approximate constructions of these bands are often used. Castillo et al. suggested sophisticated and at the same time easy procedure for their estimation which, however, is based on a special type of regression function for describing S-N curve. This type of regression function called the Castillo function is suitable only for high-cycle fatigue region close to fatigue limit. The paper focuses on the Kohout and Vechet function with wider usability applied in the Castillo procedure.
6
The comparison of cyclic deformation curve determination for ADI
Zapletal J., Obrtlík K., Věchet S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2005
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z. 86
303-309
7
Regression functions for transition curves
Kohout J., Věchet S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2005
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z. 86
241-246
8
Vliv polohy zkušebního tělesa v kýlovém bloku na únavové vlastnosti ADI
Hanzlíková K., Věchet S., Kohout J.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2004
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z. 78
147-152
9
Únavové vlastnosti izotermicky zušlechtěné litiny s kuličkovým grafitem se strukturou bainitickou
Zapletal J., Věchet S., Kohout J.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2004
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z. 78
201-206
10
Simple geometrical description of the dependence of steady-state creep rate on temperature and applied stress
Kohout J., Věchet S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2004
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z. 78
153-158
11
Q-learning: from discrete to continuous representation
Věchet S., Krejsa J.
Elektronika : konstrukcje, technologie, zastosowania
|
2004
|
Vol. 45, nr 8-9
12-14
EN
Q-learning algorithm in its standard form is limited by discrete states and actions. In order to improve quality of the control the algorithm must be modified to enable direct use of continuous variables. One possible way, presented in the paper, is to replace the table, by suitable approximator.
PL
Algorytm metody Q-learning w swej standardowej formie jest ograniczony przez dyskretne stany i działania. W celu ulepszenia jakości sterowania algorytm ten trzeba zmodyfikować, aby umożliwić bezpośrednie wykorzystanie zmiennych ciągłych. Jednym z możliwych sposobów jest przedstawione w artykule zastąpienie tablicy odpowiednim aproksymatorem.
12
Global versus local approximation in inverse problems
Krejsa J., Věchet S., Pulchart J.
Elektronika : konstrukcje, technologie, zastosowania
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2004
|
Vol. 45, nr 8-9
57-60
EN
The paper compares global end local approximation methods used in inverse problems. Global approximators are represented by feedforward multilayer neural network (FFNN); local approximators are represented by Locally Weighted Regression (LWR) and Receptive Field Weighted Regression (RFWR).
PL
W artykule porównano metody globalnej i lokalnej aproksymacji w zagadnieniach odwrotnych. Aproksymatory globalne reprezentuje wielowarstwowa sieć neuronowa ze sprzężeniem do przodu (FFNN), natomiast aproksymatory lokalne regresja lokalnie ważona (LWR) oraz regresja ważona pola otwartego (RFWR).
13
Content available remote Únavové vlastnosti litiny s kuličkovým grafitem v závislosti na asymetrii zátěžného cyklu
Věchet S., Kohout J., Hanzlíková K.
Archiwum Odlewnictwa
|
2004
|
R. 4, nr 11/2
283--287
CS
V předložené práci jsou uvedeny výsledky výzkumu zaméřeného na vysokocyklové únavové vlastnosti litin s kuličkovým grafitem sbainitickou strukturou matrice. Únavové vlastnosti jsou hodnoceny na základě stanovení Wöhlerových křivek a meze úavy. Zvláštní pzornost je věnována vlivu asymetrie zátěžného cyklu na hodnoty meze únavy. Pro studovaný materiál byl stanoven Smithůdv a Haighův diagram.
14
The influence comparison of creep testing and air traffic on microstructure of cast Ni - base superalloy inconel 713 LC
Němec K., Podrábský T., Věchet S., Juliš M., Pospíšilová S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2003
|
z. 76
177-182
EN
In the working conditions of the jet engines gas turbines of supersonic plane blades are loaded by the cycles, this process is the function of the time, temperature and stress. The blade are exposed to influence of degradable processes namely of the high-temperature corrosion, fatigue process and creep. As the result of short overloading as it happens for instance during the starts and landing, eventually in some other irregularities of the jet engine function, the increase of stress and temperature leads to the changes of microstructure and properties. The presented work is aimed at the study of structural changes of the material Inconel 7I3 LC subjected to short-time creep tests at s = 180 MPa and temperature 900°C and after air traffic. The thesis is a part of a complex project aimed at study of mechanical-structural characteristics of the polycrystalline nickel-base super alloy.
15
Optimization in dwell length of adi isothermal transformation
Hanzlíková K., Věchet S., Kohout J.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2003
|
z. 76
157-162
EN
Austempered ductile iron (ADI) is usually obtained by isothermal heat treatment. Owing to its excellent mechanical as well as technological properties, ADI belongs among prospective structural materials. Recently it is applied also to castings for dynamically loaded machine details, e.g. gear and traversing wheels, crankshafts of motor-cars, vans and trucks, swivel pins, rail brakes and pressure pipes in oil industry [1]. Generally said, ADI castings are applied (i) as a substitution of details made of steel (forged pieces, workpieces or weldments), (ii) instead of the castings made of nodular cast iron with lower level of strength properties to increase its loading capacity and/or its service life, (iii) for the details designed specially for ADI application. Microstructure and mechanical properties of ADI can be substantially influenced by the condition of heat treatment. While the austenitization conditions play only marginal role, the conditions of isothermal transformation, i.e. transformation temperature and the dwell at it, influence the resulting structure of ADI and consequently its mechanical properties very substantially [2-6]. Present paper is devoted to the study how the dwell of isothermal transformation in the range of 2 minutes to 9 hours influences the structure as well as the static and fatigue properties of unalloyed ADI transformed at temperature of 380 °C.
16
Lomové chování plynule lité ocelové bramy v intervalu teplot 25 (stopni) C - 1450 (stopni) C
Dobrovská J., Kozelský P., Dobrovská V., Věchet S., Stránský K.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2003
|
z. 76
69-74
17
Walker's approach and its modification in the Haigh diagram construction
Kohout J., Věchet S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2002
|
z. 75
77-80
18
Vliv asymetrie zátěžného cyklu na únavové vlastnosti litiny s kuličkovým grafitem
Hanzlíková K., Věchet S., Kohout J.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2002
|
z. 75
73-76
19
Fatigue behaviour of ferritic nodular cast iron at various asymmetry of loading cycle
Kohout J., Věchet S.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2001
|
Vol. 279, z. 72
89-92
20
Strain and fracture behaviour of austempered ductile iron
Kohout J., Věchet S., Podrábský T.
Zeszyty Naukowe. Mechanika / Akademia Techniczno-Rolnicza w Bydgoszczy
|
2001
|
Z. 50(233)
133-140
EN
Tensile tests of an unalloyed ADI with the matrix created by upper bainite containing from 30 to 35 % of retained austenite were performed in a temperature range -196 to +200 °C. The temperature dependence of true fracture stress, elongation to fracture, and reduction in area is separated into three regions. Unmonotonous temperature dependence of yield points defined by plastic strain from 0.05 to 2 % in the middle region is the evidence of the stress induced phase transformation of retained austenite into martensite before these values of plastic strain are reached.
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