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1
Content available remote Modernizacje turbogeneratorów serii TWW realizowane przez EthosEnergy Poland S.A.
Baron D., Maniara R.
Przegląd Elektrotechniczny
|
2017
|
R. 93, nr 11
1--10
PL
W eksploatacji turbogeneratorów zachodzi szereg zjawisk fizycznych prowadzących do pogarszania ich stanu technicznego (np. procesy starzeniowe i zmęczeniowe materiałów konstrukcyjnych) i w efekcie zwiększania ryzyka eksploatacyjnego, które są szczególnie nasilone w okresie eksploatacji zaawansowanej, gdy turbogenerator zbliża się do końca zaprojektowanego czasu życia. Aby turbogenerator mógł dalej spełniać aktualne wysokie wymagania eksploatacyjne, rozwiązaniem może być jego modernizacja. W artykule zaprezentowano wybrane zagadnienia techniczne z zakresu modernizacji turbogeneratorów serii TWW (z chłodzeniem wodorowo-wodnym, np. TWW-200-2, TWW-200-2A, TWW-320-2Y3, TWW-500-2), wdrożone przez EthosEnergy Poland S.A. w turbogeneratorach eksploatowanych w Polsce i za granicą. Modernizacja turbogeneratorów serii TWW jest sprawą istotną, gdyż stanowią one podstawowe jednostki wytwórcze nie tylko polskiego systemu elektroenergetycznego. W artykule przedstawiono udoskonalenia modernizacyjne wybranych węzłów konstrukcyjnych, które umożliwiają podwyższenie mocy znamionowej i wydajności turbogeneratorów, zwiększenie ich trwałości i niezawodności eksploatacyjnej, jak również znaczącą poprawę poziomu ich bezpieczeństwa eksploatacyjnego. Przedstawione zmiany modernizacyjne zostały opracowane w oparciu o liczne analizy, optymalizacje techniczne i dotyczą całego turbogeneratora, tj. jego stojana, wirnika, systemu chłodzenia jak również innych strategicznych komponentów. Wszystkie prezentowane rozwiązania charakteryzują się zastosowaniem wysokiej jakości nowoczesnych materiałów. Wyniki badań i pomiarów zmodernizowanych turbogeneratorów w eksploatacji potwierdziły poprawność i słuszność przyjętych założeń konstrukcyjnych.
EN
Operational phenomena occurring in turbogenerators like deteriorations, ageing and fatigue processes increase operational risk, especially when turbogenerators approach their expected life-time, then an upgrade/modernization of the turbogenerators may become necessary in order to meet the nowadays operational requirements. The paper presents some selected technical designs used in modernized TWW-series turbogenerators (with hydrogen-water cooling, on the example of turbogenerators type TWW-200-2, TWW-200-2A, TWW-320-2Y3, TWW-500-2), successfully implemented by EthosEnergy Poland S.A. in many turbogenerators operated in Poland and abroad. Modernization of TWW-series turbogenerators is important subject, because the turbogenerators are fundamental power units in electric power systems in Poland and some other countries. The paper presents some modernizing improvements of selected designing and constructional areas, which enable to upgrade the turbogenerator nominal power, to rise its operational efficiency, reliability, safety and extend the turbogenerator life-time. The presented modernizing solutions and modifications were developed based on extensive engineering analyses and optimizations and they are applicable to the whole turbogenerator, i.e. its stator, rotor, cooling/ventilation system as well as other strategic components. All the solutions are characterized by application of high-quality modern materials. Tests and diagnostics results of the modernized turbogenerators in operation have confirmed the correctness and accuracy of the predicted modernizing expectations.
2
Content available remote Modernizacja wirnika generatora GTHW-360
Adamek J., Kapinos J., Kardas D., Krok R., Maniara R., Sieradzki S.
Przegląd Elektrotechniczny
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2015
|
R. 91, nr 10
6-10
PL
W artykule przedstawiono zakres modernizacji wirnika generatora GTHW-360 w celu podwyższenia mocy generatora do 396 MW przy cosφ=0,85 ind. oraz przy cosφ=0,95 poj. Wyniki obliczeń cieplnych porównano z wynikami pomiarów wykonanych na kilku generatorach GTHW-360. Na bazie doświadczeń remontowych oraz uzyskanych wyników obliczeń cieplnych przedstawiono propozycję modernizacji uzwojenia wzbudzenia w strefie połączeń czołowych.
EN
The article presents the scope of GTHW-360 generator rotor modernization in order to raise the generator power up to 396 MW at cosφ=0.85 (inductive) and cosφ=0.95 (capacitive). There are presented results of thermal calculations in comparison with results of the measurements of some GTHW-360 generators. On the basis of the repairing experiences and the thermal calculations, the article presents a proposal of modernization of excitation winding in the end winding area.
3
Content available remote Modernizacja wentylacji turbogeneratorów dużej mocy
Adamek J., Kardas D., Maniara R., Sieradzki S., Prysok E.
Przegląd Elektrotechniczny
|
2015
|
R. 91, nr 10
11-18
PL
Zwiększanie mocy znamionowej turbogeneratorów wymusza intensyfikację systemu ich chłodzenia W artykule opisano założenia projektowo-konstrukcyjne zmodernizowanych przez firmę EthosEnergy Poland S.A. (dawniej TurboCare Poland S.A.) wentylatorów turbogeneratorów dużej mocy typu TWW-230, TGHW-63, TGW-200. Na podstawie parametrów punktów pracy przed i po modernizacji wentylatorów, wykazano zwiększenie intensywności chłodzenia przedmiotowych turbogeneratorów.
EN
Rated power increase of turbogenerators forces to intensify the cooling system. The paper describes the designing assumptions made for blowers of high-power turbogenerators type TWW-230, TGHW-63, TGW-200 modernized by EthosEnergy Poland S.A. (formerly TurboCare Poland S.A.). Based on the parameters of working points before and after modernization of the blowers, there is confirmed increase of the turbogenerator cooling intensity.
4
Badania własności dynamicznych czół uzwojenia stojana generatora
Maniara R., Kardas D.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2014
|
z. 103
131--132
PL
Jednym z ważnych zagadnień techniki są drgania elementów maszyn, wynikające bezpośrednio z własności sprężystych zastosowanych materiałów konstrukcyjnych. W badaniach częstotliwości drgań własnych połączeń czołowych, podstawowym celem jest określenie charakterystyk amplitudowo-częstotliwościowych. Struktura widma drgań wyznaczana podczas badań własności dynamicznych czół uzwojenia określa indywidualne cechy konstrukcji maszyny elektrycznej oraz obrazuje dyssypację energii drganiowej, związanej między innymi ze stanem obciążenia oraz stanem technicznym obiektu.
5
Content available remote Wpływ modernizacji wentylatorów osiowych z tylnymi łopatkami kierowniczymi na wzrost mocy znamionowej generatorów typu TWW-230
Adamek J., Krok R., Prysok E., Kardas D., Maniara R.
Przegląd Elektrotechniczny
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2014
|
R. 90, nr 1
232--235
PL
W artykule przedstawiono zakres modernizacji wentylatorów osiowych do generatorów typu TWW-230 z tylnymi łopatkami kierowniczymi w osłonach. Na wybranych przykładach zastosowań zaprezentowano wyniki obliczeń cieplnych zweryfikowanych pomiarami generatora typu TWW-230 przed i po modernizacji wentylatorów oraz określono wpływ modernizacji wentylatorów z tylnymi łopatkami kierowniczymi na wzrost mocy znamionowej generatora.
EN
This article presents the scope of axial-flow fans modernization with back guide blades in shields for the generators type TWW-230. Based on the selected examples of applications, there are presented results of thermal calculations that were verified by measurements of the generator type TWW-230, before and after the fan modernization. Additionally there are described the influence of fan modernization with back guide blades on the increase of generator rated power.
6
Content available remote Badania własności dynamicznych czół uzwojenia stojana generatora
Maniara R., Kardas D.
Przegląd Elektrotechniczny
|
2012
|
R. 88, nr 4a
42-46
PL
W artykule przedstawiano wyniki obliczeń numerycznych oraz analiz doświadczalnych przeprowadzonych dla stojanów generatorów dużej mocy. Przeprowadzone obliczenia umożliwiły wyznaczenie wartości częstotliwości drgań własnych czół uzwojeń. Wyniki obliczeń numerycznych w dużym stopniu korelują się z danymi pomiarowymi. Przeprowadzone obliczenia pozwalają na optymalizację właściwości dynamicznych zawieszenia czół uzwojenia.
EN
In the article numerical calculation and experimental results of natural frequencies for end-winding of synchronous of generator stator are presented. The numerical model was draw up using the finite element methods. This calculations allow for designing the end-winding out of work scope in the resonance and for extending the of electric machines life.
7
Content available remote Microstructure evaluation of the Al-Ti alloy with magnesium addition
Labisz K., Dobrzański L. A., Maniara R., Olsen A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2011
|
Vol. 47, nr 1
75--82
EN
Purpose: Effects of magnesium additions to Al alloy with 2% Ti addition on the microstructure, phase morphology and distribution and mechanical properties were investigated. Here are presented mainly microstructure changes after solution heat treatment concerning mainly grain uniformity and intermetallic phases of the aluminium - titanium alloy with a content of 2 and 4 % of magnesium addition. The purpose of this work was also to determine the solution heat treatment conditions of the investigation alloys. Design/methodology/approach: The reason of this work was to determine the heat treatment parameters influence, particularly SHT temperature and time onto the changes of the microstructure of the investigated material, as well to determine which intermetallic phases occur after the heat treatment performed, and how is the particles morphology in as cast state compared to structure after heat treatment. Findings: After solution heat treatment for 4 hours the structure changes in a significant way. The grains are larger and no more uniform as in the as cast state. The most stable intermetallic in the Al-Ti system is the Al3Ti phase. The solution heat treatment time should be greater than 4 hours to ensure a proper solution of titanium and magnesium in the Al-a solid solution. Research limitations/implications: The investigated aluminium samples were examined metallographically using optical microscope with different image techniques, scanning electron microscope and also analyzed using a Vickers micro-hardness tester, also EDS microanalysis was carried out. Practical implications: As an implication for the practice an alloy can be developed with increased properties, which could be of great interest for the automotive or aerospace industry. There are existing many different investigation areas and the knowledge found in this research shows one of interesting investigation direction. Originality/value: The combination of light weight and high strength achieved in the Al-Ti alloys is very attractive for aerospace and automotive industries. Addition of magnesium into the Al-Ti alloy could help also to reveal the existence new unknown phases.
8
Content available Postacie drgań własnych czół uzwojenia stojana generatora
Maniara R., Kardas D.
Maszyny Elektryczne : zeszyty problemowe
|
2010
|
Nr 87
119-126
EN
In the article numerical calculation results of natural frequencies for end-winding of synchronous of generator stator are presented. The numerical model was draw up using the finite element methods. This calculations allow for designing the end-winding out of work scope in the resonance and for extending the of electric machines life.
9
Content available remote Microstructures of Mg-Al-Zn and Al-Si-Cu cast alloys
Tański T., Dobrzański L. A., Maniara R.
Journal of Achievements in Materials and Manufacturing Engineering
|
2010
|
Vol. 38, nr 1
64-71
EN
Purpose: The aim of this paper was to investigate the structure of the MCMgAl6Zn1 magnesium and ACAlSi9Cu aluminium cast alloy in as-cast state. Design/methodology/approach: The following results concern the microstructure of the cast magnesium and aluminium alloys using ZEISS SUPRA 25, Opton DSM-940 scanning and LEICA MEF4A light microscopy, X-ray qualitative microanalysis as well as X-ray analysis. Findings: The analysis of the structure magnesium alloy consists of the solid solution á – Mg (matrix) of the secondary phase g – Mg17Al12 evenly located in the structure. The structure creates agglomerates in the form of needle precipitations, partially coherent with the matrix placed mostly at the grain boundaries. The AC AlSi9Cu and AC AlSi9Cu4 cast aluminium alloys are characterised by a dendritic structure of the á solid solution - as the alloy matrix, as well are characterised by a discontinuous â–Si phase forming the á+â eutectic grains, with a morphology depending on the silicon and copper mass concentration. Research limitations/implications: Taking into account the fact that some of the properties are of great importance only for the surface of the material, the future investigation will concern modelling of the alloy surface using surface layers deposition methods like physical vapour deposition methods. Practical implications: A desire to create as light vehicle constructions as possible and connected low fuel consumption have made it possible to make use of magnesium and aluminium alloys as constructional material in automotive industry. Originality/value: Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The above mentioned requirements and expectations regarding the contemporary materials are met by the non-ferrous metals alloys used nowadays, including the magnesium and aluminium alloys.
10
Content available remote Microstructure and mechanical properties of the Al-Ti alloy with cerium addition
Dobrzański L. A., Labisz K., Maniara R., Olsen A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
|
Vol. 37, nr 2
622-629
EN
Purpose: In this work there are presented the investigation results of mechanical properties and microstructure concerning mainly intermetallic phases of the aluminium – titanium alloy with a defined content of 2 and 4 % of cerium addition. The purpose of this work was also to determine the heat treatment conditions for solution heat treatment of the investigation alloys. Design/methodology/approach: The reason of this work was to determine the heat treatment influence, particularly solution heat treatment time to the changes of the microstructure, as well to determine which intermetallic phases occur after the heat treatment performed, and how is the morphology of these particles. Findings: After solution heat treatment for 4 hours the structure changes. The grains are larger and no more uniform as showed before. The most stable intermetallic in the Al-Ti system is the Al3Ti phase. The solution heat treatment time should be greater than 4 hours to ensure a proper solution of titanium and cerium in the Al-á solid solution. Research limitations/implications: The investigated aluminium samples were examined metallographically using optical microscope with different image techniques, scanning electron microscope and also analyzed using a Vickers micro-hardness tester, also EDS microanalysis was made. Practical implications: As an implication for the practice a new alloy can be developed, some other investigation should be performed in the future, but the knowledge found in this research shows an interesting investigation direction. Originality/value: The combination of light weight and high strength Ti-based alloys is very attractive for aerospace and automotive industries. Furthermore, the presence of calcium cerium into existence new unknown phases as well can enhance the thermal stability of ternary Al-Ti-Ce alloy because of its higher melting point then Al-Ti.
11
Content available remote Effect of cooling rate on the solidification behaviour of MC MgAl6Zn1 alloy
Dobrzański L. A., Król M., Tański T., Maniara R.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
|
Vol. 37, nr 1
65-69
EN
Purpose: The goal of this paper is to present the thermal characteristics of magnesium alloy using the novel Universal Metallurgical Simulator and Analyzer Platform. Design/methodology/approach: The objective of this work is determine the liquidus, solidus temperature and beginning nucleation temperature to understanding crystallization of magnesium alloys. Findings: The research show that the thermal analysis carried out on UMSA Technology Platform is an efficient tool for collect and calculate thermal parameters. It was determined that the higher solidification rate decreases the solidus temperature. In addition, it was observed that the beginning of nucleation of .(Mg)-ß(Mg-Mg17Al12) eutectic temperature constituent increases when the solidification rate increases. Research limitations/implications: This paper presents results for one alloy – MC MgAl6Zn1 only, cooled with three different solidifications rate i.e. 0.6, 1.2 and 2.4oC/s, for assessment for the liquidus, solidus temperatures and describe a beginning of nucleation of .(Mg)-ß(Mg-Mg17Al12) eutectic. Practical implications: The parameters described can be applied in metal casting industry for selecting magnesium ingot preheating temperature for semi solid processing to achieve requirements properties or to predict how to prepare parameters to heat treatment. Originality/value: The paper contributes to better understanding and recognition an influence of different solidification condition on non-equilibrium thermal parameters of magnesium alloys.
12
Wpływ naprężeń wstępnych na wybrane obliczane parametry drganiowe maszyn elektrycznych
Maniara R., Kardas D.
Energetyka
|
2009
|
nr 9
592-598
PL
Duże siły i amplitudy drgań występujące w pobliżu lub stanie rezonansu są niebezpieczne dla maszyn elektrycznych. Naprężenia dynamiczne towarzyszące drganiom przy częstotliwościach rezonansowych prowadzą do zniszczenia zmęczeniowego. Dlatego maszyna elektryczna powinna być tak zaprojektowana, aby uniknąć pracy w pobliżu rezonansu, a więc jej częstotliwości drgań własnych powinny znajdować się w bezpiecznej odległości od częstotliwości sił wymuszających. Zaprezentowano wpływ naprężeń wstępnych na częstotliwość drgań własnych wybranego węzła konstrukcyjnego maszyny elektrycznej.
EN
High vibration forces and amplitudes occurring in the resonance state or close to it, are dangerous for electric machines. Dynamic stresses, accompanying the vibrations close to resonance frequencies, lead to fatigue failure. That is why an electric machine must be designed in order to avoid occurring of working vibrations close to the resonance state – it means that the frequency of its free vibrations must be in a safe distance from frequencies of exciting forces. Presented is an influence of initial stresses on free vibration frequency of a selected constructional node of an electric machine.
13
Content available remote Effect of cooling rate on the solidification behavior of magnesium alloys
Dobrzański L.A., Król M., Tański T., Maniara R.
Archives of Computational Materials Science and Surface Engineering
|
2009
|
Vol. 1, nr 1
21-24
EN
Purpose: The goal of this paper is to present the thermal characteristics of magnesium alloy using the novel Universal Metallurgical Simulator and Analyzer Platform. Design/methodology/approach: The objective of this work is determine the liquidus, solidus temperature and beginning nucleation temperature to understanding crystallization of magnesium alloys. Findings: The research show that the thermal analysis carried out on UMSA Technology Platform is an efficient tool for collect and calculate thermal parameters. The formation temperatures of various thermal parameters and hardness are shifting with an increasing cooling rate. Research limitations/implications: This paper presents results for one alloy. MCMgAl12Zn1 only, cooled with three different solidifications rate i.e. 0.6, 1.2 and 2,4 �°C/s, for assessment for the liquidus, solidus temperatures and describe a beginning of nucleation of �α(Mg)-β(Mg-Mg17Al12) eutectic and its influence on the mechanical properties. Further investigations should be concentrating on assessment an influence of different solidification rate on microstructure. Practical implications: The parameters described can be applied in metal casting industry for selecting magnesium ingot preheating temperature for semi solid processing to achieve requirements properties. Originality/value: The paper contributes to better understanding and recognition an influence of different solidification condition on non-equilibrium thermal parameters of magnesium alloys.
14
Content available remote Thermal analysis of the MCMgAl9Zn1
Dobrzański L. A., Król M., Tański T., Maniara R.
Archives of Materials Science and Engineering
|
2008
|
Vol. 34, nr 2
113-116
EN
Purpose: The goal of this paper is to present the new methodology to determine the thermal characteristics of magnesium alloy using the novel Universal Metallurgical Simulator and Analyzer Platform. Design/methodology/approach: The experiments were performed using the novel Universal Metallurgical Simulator and Analyzer Platform. Material used in this experiment is experimental magnesium alloy made as-cast. Findings: The research show that the thermal analysis carried out on UMSA Technology Platform is an efficient tool for collect and calculate thermal parameters. The formation temperatures of various thermal parameters are shifting with an increasing cooling rate. Research limitations/implications: This paper presents results for one alloy . MCMgAl9Zn1 only cooled with two different solidifications rate i.e. 0.6 and 2°C/s, for assessment for the liquidus, solidus temperatures and describe a beginning of nucleation of α(Mg)-β(Mg-Mg17Al12) eutectic. Further investigations should be concentrating on assessment an influence of different solidification rate on microstructure and mechanical properties. Practical implications: The parameters described can be applied in metal casting industry for selecting magnesium ingot preheating temperature for semi solid processing. Originality/value: The paper contributes to better understanding and recognition an influence of different solidification condition on non-equilibrium thermal parameters of magnesium alloys.
15
Effect of cooling rate on the solidification behavior of MC MgAl6Zn1 alloy
Dobrzański L. A., Król M., Tański T., Maniara R.
Archives of Materials Science
|
2008
|
Vol. 29, nr 3
110-117
EN
In this work effect of cooling rate on thermal characteristic results of MC MgAl6Zn1 cast alloy have been described. The solidification process was studied using the cooling curve and crystallization curve at solidification rate ranging from 0.6 degree C/s up to 2.4 degree C/s. It was determined that the higher solidification rate decreases the solidus temperature. In addition, it was observed that the beginning of nucleation of alpha(Mg)-betha(Mg-Mg17Al12) eutectic temperature constituent increases when the solidification rate increases.
16
Content available remote Modelling of mechanical properties of Al-Si-Cu cast alloys using the neural network
Dobrzański L. A., Maniara R., Sokolowski J. H., Krupiński M.
Journal of Achievements in Materials and Manufacturing Engineering
|
2007
|
Vol. 20, nr 1-2
347-350
EN
Purpose: The paper presents some results of the research connected with the development of new approach based on the neural network to predict the chemical composition and cooling rate to the mechanical properties of Al-Si-Cu cast alloys. The independent variables in the model are chemical composition of Al-Si-Cu cast alloys and cooling rate. The dependent parameters are hardness, microhardness, yield strength and apparent elastic limit. Design/methodology/approach: The experimental alloy used for training of neural network was prepared at the University of Windsor (Canada) in the Light Metals Casting Laboratory, in a 10 kg capacity ceramic crucible. Thermal analysis tests were conducted using the UMSA Technology Platform. Compression tests were conducted at room temperature using a Zwick universal testing machine. Prior to testing an extensometer was used to minimize frame bending strains. Compression specimens were tested corresponding to each of the three cooling rate. Rockwell F-scale hardness tests were conducted at room temperature using a Zwick HR hardness testing machine. Vickers microhardness tests were conducted using a DUH 202 microhardness testing machine. Findings: The results of this investigation show that there is a good correlation between experimental and predicted dates and the neural network has a great potential in mechanical behavior modeling of Al-Si-Cu castings. Practical implications: The worked out model can be applied in computer system of Al-Si-Cu casting alloys selection and designing for Al-Si-Cu casting parts. Originality/value: Original value of the work is applied the artificial intelligence as a tools for designing the required mechanical properties of Al-Si-Cu castings.
17
Content available remote Microstructure and mechanical properties of AC AlSi9CuX alloys
Dobrzański L. A., Maniara R., Krupiński M., Sokolowski J. H.
Journal of Achievements in Materials and Manufacturing Engineering
|
2007
|
Vol. 24, nr 2
51-54
EN
Purpose: In order to gain a better understanding of how to control the as-cast microstructure, it is important to understand the evaluation of microstructure during solidification and understanding how influence the changes of chemical concentration on this microstructure and mechanical properties. In this research, the effect of Cu content on the microstructure and mechanical properties of AC AlSi9CuX series alloys has been investigated. Design/methodology/approach: The experimental alloy used in this investigation were prepared at the University of Windsor (Canada) in the Light Metals Casting Laboratory, by mixing the AC AlSi5Cu1(Mg) commercial alloys and two master alloys AlSi49 and AlCu55, in a 10 kg capacity ceramic crucible. Optical microscope, transition electron microscope and scanning electron microscope were used to characterize the microstructure and intermetallic phases. Secondary dendrite arm spacing measurements were carried out using an Leica Q-Win(TM) image analyzer. Compression tests were conducted at room temperature using a Zwick universal testing machine. Rockwell F-scale hardness tests were conducted at room temperature using a Zwick HR hardness testing machine. Vickers microhardness tests were conducted using a DUH 202 microhardness testing machine. Findings: It was found that the increase of Cu content to 2 wt% leads to change of the Al+Si eutectic morphology, resulting in a grate increase in the ultimate tensile strength and ductility values compared to the alloys include 1 and 4 wt % of Cu. Based on the X-ray phase analysis was found, that change of Cu content don't influences on the phases composition of investigated alloy. Practical implications: The aim of this work is describe in detail the solidification process in a number of AC AlSi9CuX foundry alloys. In investigated alloys there were identified five phases, which can suggest together with thermal analysis, that in these alloys occur four solidification reactions. Originality/value: The carried out work confirmed the solidification reaction of AC AlSi9CuX foundry alloys and shown influence of Cu content on the microstructure and mechanical properties.
18
Content available remote Computer aided method for quality control of automotive Al-Si-Cu cast components
Dobrzański L. A., Krupiński M., Maniara R., Sokolowski J. H.
Journal of Achievements in Materials and Manufacturing Engineering
|
2007
|
Vol. 24, nr 2
151-154
EN
Purpose: The technological progress in material engineering causes the continuous need to develop product testing methods providing comprehensive quality evaluation. In material engineering it is the images obtained by various methods that have become the source of information about materials. Design/methodology/approach: The presented methodology, making it possible to determine the types and classes of defects developed during casting the elements from aluminium alloys, making use photos obtained with the flaw detection method with the X-ray radiation. The tests indicate to the applicability of neural networks for this task. It is very important to prepare the neural network data in the appropriate way, including their standardization, carrying out the proper image analysis and correct selection and calculation of the geometrical coefficients of flaws in the X-ray images. Findings: In classical computer algorithms even a slight rotation or change in lighting can binder the proper interpretation and alternation of variable input data. To eliminate this hindrance the programming can be converted by specifying such features of the structure element that remain most significant and effect the similarities of the analysed images. In neural networks this particular feature needs not to be specified - if necessary, the neural network spots it automatically. Practical implications: The computer aided methodology of the quality control of the light Al and Mg based alloys may be used by manufacturers of subassemblies and elements of car engines. Originality/value: The value of the applied methodology was to correct identify the casting effects that occurred during the casting process.
19
Content available remote Analysis of influence of chemical composition of Al-Si-Cu casting alloy on formation of casting defects
Dobrzański L. A., Krupiński M., Zarychta P., Maniara R.
Journal of Achievements in Materials and Manufacturing Engineering
|
2007
|
Vol. 21, nr 2
53-56
EN
Purpose: A methodology of the computer-aided determining relationship between chemical composition of aluminium alloy and castings quality was presented in the paper. Design/methodology/approach: To resolve the problem artificial neural networks were used. Classification problems were evaluated by the consideration mainly the values of mistakes and correct answers of networks for test data. On the basis of data analyzed by the neural network, which has the best quality classification of chemical composition of tested material, the concentration of alloying elements range, which have an effect on formation casting defects, were developed to eliminate them in the future. Findings: Combining of all methods making use of chemical composition of aluminium alloy and neural networks will make it possible to achieve a better casting quality. Research limitations/implications: The presented issues may be use, among others, for manufacturers of car subassemblies from light alloys, where meeting the stringent quality requirements ensures the demanded service life of the manufactured products. Originality/value: The correctly specified number of chemical composition of aluminium alloy enables such technological process control where the number of castings defects can be reduced by means of the proper correction of the process.
20
Content available remote The effect of cooling rate on microstructure and mechanical properties of AC AlSi9Cu alloy
Dobrzański L. A., Maniara R., Sokolowski J. H.
Archives of Materials Science and Engineering
|
2007
|
Vol. 28, nr 2
105-112
EN
Purpose: In this work the effect of cooling rate on the size of the grains, SDAS, size of the β precipitation and thermal characteristic results of AC AlSi9Cu cast alloy have been described. The solidification process was studied using the cooling curve and crystallization curve at solidification rate ranging from 0,16 °Cs -1 up to 1,04 °Cs -1. Design/methodology/approach: The experimental alloy used in this investigation was prepared by mixing in suitable proportion the AC AlSi5Cu1(Mg) commercial alloys and two master alloys AlSi49 and AlCu55. Thermal analysis tests were made using the UMSA Technology Platform. Cooling curve thermal analysis was performed on all samples using high sensitivity thermocouples of K type that were protected in a stainless steel sheath and data were acquired by a high speed data acquisition system linked to a PC computer. Each chilled sample was sectioned horizontally where the tip of the thermocouple was located and it was prepared by standard grinding and polishing procedures. The final stage of polishing was done using commercial silicon oxide slurry. Optical microscopy was used to characterize the microstructure and intermetallic phases. Secondary dendrite arm spacing measurements were carried out using a Leica Q-Win ™ image analyzer. The UTM measurements were carried out using a Zwick testing machine. Findings: Increasing the cooling rate increases significantly the liquidus temperature, nucleation undercooling temperature, solidification range and decreases the recalescence undercooling temperature. Increasing cooling rate refines all microstructural features including secondary dendrite arm spacing (SDAS) and intermetallic compounds and improves silicon modification level. Research limitations/implications: The results presented in this paper show results only for the one alloy - AC AlSi9Cu, and for the assessment of the Silicon Modification Level didn't include the arrangement of a Si crystal in a matrix. Practical implications: The aim of this work is describe in detail the solidification process in a number of AC AlSi9Cu foundry alloy. Cooling rates applied in this experiment occur in cross section of a bloc engine. The results shows the effect of different cooling rates on the microstructural features and the characteristic parameters of the cooling curve of ACAlSi9Cu alloy. Originality/value: Original value of the work is applied the artificial intelligence for the assessment of the Silicon Modification Level.
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