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  1. 20 Inżynieria Materiałowa
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  1. 10 Dobrzański L. A.
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1
Content available Selection of materials for repairing punctures of metal skin of semi-monocoque structures using composite patches
Godzimirski Jan, Rośkowicz Marek, Barca Iga
Technologia i Automatyzacja Montażu
|
2023
|
nr 2
19--32
EN
For repairing punctures of skin of semi-monocoque structures under field conditions, simple methods are sought to guarantee the reliability of the repaired structure. Therefore, adhesive joints and composite materials are being increasingly used in repairs. During repairs using adhesion, an important aspect that affects the quality of the joint is the selection of the adhesive and the quality of surface preparation of the parts to be joined. This is necessary to get the right bond strength and durability of the joint in working environments characterized by extreme temperatures and exposure to chemicals and moisture. The purpose of the study was to select an adhesive with good strength properties for bonding AW2024T3 aluminum sheets to carbon and glass composites, and to analyze the effect of metal surface preparation on the strength of adhesive joints (grinding, sandblasting and chemical surface preparation). The tests were carried out on overlap (metal-composite) specimens. For selected adhesives, strength tests were also carried out on specimens replicating the repaired damage with a diameter of 20 mm of metal skin repaired by different methods, including composite patches and adhesive joints. The specimens were loaded in tension and loss of stability. The tests made it possible to determine the requirements for composite patches used for repairing upper and lower airframe wing skins.
PL
Do napraw przebić pokryć konstrukcji półskorupowych w warunkach polowych, poszukuje się prostych metod, które zagwarantują niezawodność naprawianej struktury. Dlatego coraz częściej w naprawach wykorzystuje się połączenia adhezyjne i materiały kompozytowe. Podczas napraw z zastosowaniem klejenia ważnym aspektem, który wpływa na jakość połączenia, jest dobór odpowiedniego kleju oraz jakość przygotowania powierzchni klejonych elementów. Jest to niezbędne do uzyskania odpowiedniej siły wiązania i trwałości połączenia w środowisku pracy, które cechują ekstremalne temperatury oraz narażenie na działanie chemikaliów i wilgoci. Celem badań był dobór kleju o dobrych właściwościach wytrzymałościowych do łączenia blach AW2024T3 z kompozytami węglowymi i szklanymi oraz analiza wpływu przygotowania powierzchni metalowych na wytrzymałość połączeń adhezyjnych (szlifowanie, piaskowanie i chemiczne przygotowanie powierzchni). Badania przeprowadzono na próbkach zakładkowych (metalowo-kompozytowych). Dla wybranych klejów wykonano również badania wytrzymałościowe próbek imitujących naprawione uszkodzenie o średnicy 20 mm pokrycia metalowego naprawianego różnymi metodami, w tym z zastosowaniem łat kompozytowych i połączeń adhezyjnych. Próbki obciążano na rozciąganie i utratę stateczności. Przeprowadzone badania pozwoliły określić wymagania dotyczące łat kompozytowych stosowanych do napraw górnych i dolnych pokryć skrzydeł płatowców.
2
Content available remote Możliwości wykorzystania gazociągów kompozytowych w rozbudowie gazowej sieci dystrybucyjnej
Kuczyński Szymon, Łaciak Mariusz, Spyra Czesław, Szurlej Adam, Wnęk Przemysław
Przemysł Chemiczny
|
2023
|
T. 102, nr 6
594--599
PL
Krajowy rynek gazu ziemnego należy do jednego z najszybciej rozwijających się w krajach UE. Światowe doświadczenia w zakresie zastosowania materiałów kompozytowych do budowy sieci gazociągowej oraz wyniki eksperymentalne z testów wykonanych na gazociągu z materiałów kompozytowych wskazują na możliwość zastosowania nowych materiałów w krajowym gazownictwie, zwłaszcza w obszarze dystrybucji gazu. Nowe materiały i nowe technologie wydają się być pomocne dla realizacji planów związanych zarówno z rozbudową gazowych sieci, jak i ich modernizacją.
EN
An exptl. gas pipeline made of a system of fiber-reinforced thermoplastic pipes was tested. Field tests were carried out in the operating facility of Polska Spółka Gazownictwa for 3 months. In real conditions, the continuous flow of natural gas was characterized by variable pressure and flow rate. Measurements of pressure, temp. and gas flow in the exptl. gas pipeline were carried out. The tested composite gas pipeline did not show any damage throughout the test period. There were no signs of material wear on its outer layer. No deformations, cracks, micro-cracks and bulges indicative of material defects were found.
3
Content available remote Zastosowanie wzmocnień kompozytowych w istniejących konstrukcjach
Drobiec Łukasz, Biernacki Jan
Izolacje
|
2023
|
T. 28, nr 9
48, 50--52
PL
W artykule omówiono praktyczne wykorzystanie materiałów kompozytowych współcześnie stosowanych przy wzmacnianiu istniejących konstrukcji. Zaprezentowano przekrój możliwych zastosowań i objaśniono słuszność i zasady ich doboru. W publikacji można też odnaleźć informacje na temat optymalnych sposobów stosowania wzmocnień zależności od konstrukcji wymagającej wzmocnienia.
EN
The article discusses the practical use of composite materials currently employed in strengthening existing structures. It presents an overview of possible applications and explains the rationale and principles for their selection. The publication also provides information on optimal methods for applying reinforcements, depending on the structure in need of strengthening.
4
Content available remote Numerical failure analysis of laminated beams using a refined finite element model
Layachi Maroua, Khechai Abdelhak, Ghrieb Abderrahmane, Layachi Safa
Advances in Materials Science
|
2023
|
Vol. 23, nr 1(75)
32--57
EN
In the present investigation, laminated composite beams subjected to a bending static loading are studied in order to determine their failure mechanisms and the first ply failure (FPF) load. The FPF analysis is performed using a refined rectangular plate element. The present element is formulated based on the classical lamination theory (CLT) to calculate the in-plane stresses. To achieve this goal, several failure criterions, including Tsai-Wu, Tsai-Hill, Hashin, and Maximum Stress criteria, are used to predict failure mechanisms. These criterions are implemented within the finite element code to predict the different failure damages and responses of laminated beams from the initial loading to the final failure. The numerical results obtained using the present element compare favorably with those given by the analytic approaches. It is observed that the numerical results are very close to the analytical results, which demonstrates the accuracy of the present element. Finally, several parameters, such as fiber orientations, stacking sequences, and boundary conditions, are considered to determine and understand their effects on the strength of these laminated beams.
5
Content available remote Carbon fiber reinforced polymer and tensegrity structures in search of model architectural and engineering solutions
Franta Anna, Zając Dawid
Technical Transactions
|
2022
|
Vol. 119, iss. 1
art. no. e2022013
EN
The current era of nanomaterials brings advancements in science and technology. This creates new solutions and possibilities in the creation of novel spatial structures. This study leads through the presentation of iconic architectural objects created with the use of high strength composite materials and tensegrity structure. Then presents the design process, numerical simulations of the three-way tensegrity grid prototype module. Static stress simulations were done within the simulation engine of the Fusion 360 software. Moreover, 1:1 scale prototype was developed. It could be used as a modular construction slab of a novel architectural design. One of the key characteristic features of high strength composite materials, high strength-to-weight ratio, combined with tensegrity structures allows to develop lightweight and hence very durable spatial structures. This gives tensegrity structures a very low dead load value as compared to traditional reinforced concrete structures. Thanks to the application of high strength and hence lightweight materials, the dead load of the prototype is only 0,18 kN/m².
6
Content available Turbofan Engines Efficiency, Historical Trends, and Future Prediction: A Review
Kuropatwa Michał, Wegrzyn Nicolas, Kozuba Jarosław
Safety & Defense
|
2022
|
2
82--90
EN
Technological development in the aviation business is usually dictated by diverse safety, economic, environmental, and social goals set by governments, regulatory agencies, and the market. Recently, a rapidly increasing interest in making air transportation climate neutral has been observed. The objective of this study is to analyze the historical trends of aircraft engine fuel efficiency, identify parameters affecting engine efficiency and initiate a discussion about future technology development needed to meet the expectations. The commercial turbofan engines test data comparison is provided in this study, followed by a theoretical assessment. The presented test data trends show a clear correlation between specific fuel consumption decrease and engine parameters like bypass ratio and overall pressure ratio increase, which is confirmed by theoretical assessment. Based on performed analysis results, a bypass ratio increase was indicated as the one potential path to reduce aircraft engine fuel consumption. Bypass ratio improvement could be achieved by fan diameter increase and rotation speed reduction in the case of turbofan engine architecture. A larger fan rotor requires a high torque drive and significantly increases engine weight which could be compensated by the lightweight design of the engine components, e.g., by applying composite materials.
7
Content available Selected issues from the analysis of composite vehicle bodies
Gołębiewski Łukasz, Żach Piotr
Journal of civil engineering and transport
|
2022
|
Vol. 4, No. 4
9--20
EN
Issues related to designing support frames and bodies for electric delivery vehicles (eVans) are the topic discussed by engineers around the world. Design processes are based on classic solution models which use structural steel profiles. Directions for development include the production of highly tensile steel frames with increased strength parameters. The authors of the article designed and constructed a prototype polymer body for a delivery vehicle. They conducted detailed multi-variant numerical analyses on the prototype and preliminary experimental tests. The obtainedresults clearly confirmed the correctness of the formulated thesis about the possibility of designing bodies made of structural plastics dedicated to electric vehicles. For a static-loaded parts of structure uniform stress distribution without concentration, with maximum stress value of 25 MPa was achived. For parts of structure carrying dynamic loads shape-derived stress concentration is inevitable. Nevertheless, the stress level of 96 MPa is within the limits of strength, due to the velocity-dependent material properties.
PL
Problematyka projektowania ram nośnych i zabudów pojazdów dostawczych elektrycznych typu eVan jest przedmiotem opracowań dyskusji środowiska inżynierskiego na całym świecie. Procesy projektowania bazują na klasycznych modelach rozwiązań wykorzystujących profile ze stali konstrukcyjnej. Kierunki rozwoju obejmują wytwarzanie ram wysoko wytężonych ze stali o podwyższonych parametrach wytrzymałościowych. Autorzy artykułu zaprojektowani i wykonali polimerową prototypową zabudowę pojazdu dostawczego. Przeprowadzili szczegółowe analizy numeryczne na prototypie oraz wstępne badania doświadczalne. Uzyskane wyniki jednoznacznie potwierdziły słuszność sformułowanej tezy o możliwości zaprojektowania zabudów dedykowanychpojazdom elektrycznym z tworzyw konstrukcyjnych.
8
Content available remote Recykling wyrobów kompozytowych w energetyce
Brzeziński Henryk, Zawadzka Ewa
Inżynieria Elektryczna
|
2022
|
nr 9
24--25
PL
Wyroby ze wzmacnianych żywic epoksydowych są masowo stosowane w przemyśle elektrotechnicznym (energoelektrycznym) ze względu na ich niezawodność i dobre parametry użytkowe. Takie materiały to chemo- i termoutwardzalne żywice organiczne (epoksydowe, poliestrowe, poliuretanowe i in.) wypełnione w znacznym stopniu mączkami lub piaskami kwarcowymi (60–70% wag.) oraz włóknem szklanym ciągłym lub ciętym (do 90% wag.), a wyroby z nich produkowane to izolatory, ograniczniki, rury, pręty i maszty, ale też łopaty turbin elektrowni wiatrowych, skrzynki rozdzielnic, obudowy i profile. Taka powszechność wiąże się z dużą i stale przyrastającą ilością odpadów, które nie są biodegradowalne ani (dotychczas) recyklowane na szeroką skalę. Wtórne zagospodarowanie materiałów odpadowych pochodzących z różnych strumieni procesowych (odpad produkcyjny, produkt wadliwy, produkt zużyty) do produkcji wyrobów analogicznych do pierwotnych zmniejszyłoby obciążenie środowiska odpadami składowanymi, pozwoliło zmniejszyć ilość surowców nowo produkowanych i koszty zakupu poprzez zastąpienie ich części recyklatem. Prace prowadzone w dziedzinie technologii kompozytowych w Łukasiewicz – Instytucie Elektrotechniki od 2019 roku ukierunkowane są na recykling odpadów epoksydowych w rozumieniu gospodarki obiegu zamkniętego (GOZ).
9
Content available remote Different techniques of repairing composite structures used in aircraft
Zeltiņa Sintija, Kleinhofs Martins, Chatys Irena
Composites Theory and Practice
|
2022
|
R. 22, nr 2
114--119
EN
The paper presents a fairly extensive review of the procedures and recommendations for checking the damaged repair area of various composite structures (such as sandwich or honeycomb structures) of airframe elements in military and civil airplanes (especially Boeing and Airbus airplanes and sailplanes). The presented requirements for the inspection and assessment of damage (e.g. delamination in layers or in the honeycomb, internal delamination in the laminate, and damaged fibers) should not exceed the permissible damage limits (PDL). The repair requirements (to ensure the continuing airworthiness of the structure) are largely dependent on the classification of the structure under consideration. In these analyses, a fairly important function is performed by non-destructive methods (such as ultrasonic bond testing or using eddy currents), thus assessing the degree of damage and the ongoing maintenance process.
PL
Praca przedstawia dość obszerny przegląd procedur i zaleceń sprawdzenia uszkodzonego obszaru napraw różnych struktur kompozytowych (jak warstwowych czy o strukturze plastra miodu typu „sandwich”) elementów płatowca, w samolotach wojskowych i cywilnych (szczególnie samolotów firmy Boeing i Airbus oraz szybowców). Przedstawione wymogi kontroli i oceny uszkodzeń (np. delaminacji w warstwach czy w plastrze miodu, wewnętrznych rozwarstwień w laminacie oraz uszkodzonych włókien) nie powinny przekraczać dopuszczalnych limitów uszkodzeń (PDL). Wymagania dotyczące napraw (aby zapewnić ciągłą zdatność konstrukcji do lotu) są w znacznym stopniu uzależnione od klasyfikacji rozpatrywanej konstrukcji. W tych analizach dość ważną funkcję spełniają metody nieniszczące (jak testowanie ultradźwiękowego testera wiązania czy prądy wirowe), oceniając w ten sposób stopień uszkodzenia i bieżący proces obsługi technicznej.
10
Content available Experimental investigations and finite element modelling of a suggested prosthetic foot
Jweeg M.J., Hassan A.K., Almudhaffa M.M.
Archives of Materials Science and Engineering
|
2022
|
Vol. 115, nr 1
21--33
EN
Purpose: To design and manufacture a dynamic cheap prosthetic foot compatible with amputees' requirements by introducing a natural fibre called kenaf (scientific name Hibiscus cannabinus L). Design/methodology/approach: In two cases, four suggested designs were analysed using the finite elements method (FEM) with a commercial ANSYS R1 program. The first case was a heel strike. The second was toe-off by subjecting force equal to 70 kg for both cases to select the optimal design. Findings: The foot found the tensile strength, flexural strength, impact stress, and fatigue test according to ISO 10328 standards successfully. Research limitations/implications: The selected design was analysed again using the ANSYS R1 program for weights 60, 70, and 80 kg for two sequences, one containing kenaf, to study how such additive could affect the mechanical properties and estimate the proper quality weight of the foot. The winner's design was then produced and tested in a fatigue foot tester according to ISO 10328 standards. Practical implications: The results showed that the sequence containing the natural fibres kanaf material improved the deformation by 20% for both cases (from 7.47 to 8.92 mm for the heel strike case for a weight of 80 kg for the sequence without and with kanaf, respectively), and the damping ratio increased by 50% (0. 188 and 0.273 for the sequence without and with kenaf, respectively), which means an increase in the stored energy and higher stability. Also, the mechanical properties like maximum tensile strength, flexural strength, impact stress, and natural frequency were modified. Originality/value: This paper develops an analytical and practical study to design and produce a dynamic cheap prosthetic foot made from natural fibres, which are characterized as renewable, cheap, recyclable, and environmentally friendly materials with good mechanical properties. Authors believe it is the first time to use natural kenaf fibres in the prosthetic foot manufacturing field.
11
Content available remote Shape and packing effects in particulate composites: micromechanical modelling and numerical verification
Majewski Michał, Wichrowski Michał, Hołobut Paweł, Kowalczyk-Gajewska Katarzyna
Archives of Civil and Mechanical Engineering
|
2022
|
Vol. 22, no. 2
art. no. e86, 1--22
EN
The aim of this study is to analyse the joint effect of reinforcement shape and packing on the effective behaviour of particulate composites. The proposed semi-analytical modelling method combines the Replacement Mori-Tanaka scheme, by means of which the concentration tensors for non-ellipsoidal inhomogeneities are found numerically, and the analytical morphologically representative pattern approac to account for particle packing. Five shapes of inhomogeneities are selected for the analysis: a sphere, a prolate ellipsoid, a sphere with cavities, an oblate spheroid with a cavity as well as an in homogeneity created by three prolate spheroids crossing at right angles. Semi-analytical estimates are compared with the results of numerical simulations performed using the finite element method and with the outcomes of classical mean-field models based on the Eshelby solution, e.g. the Mori–Tanaka model or the self-consistent scheme.
12
Content available remote Smarowanie MQL w obróbce skrawaniem aluminiowych materiałów kompozytowych
Karolczak Paweł
Stal, Metale & Nowe Technologie
|
2021
|
nr 11-12
23--37
PL
Materiały stosowane w budowie środków transportu, a szczególnie w lotnictwie, muszą wykazywać się zwiększonymi właściwościami, głównie wytrzymałościowymi, w stosunku do materiałów stosowanych w produkcji innych części maszyn. Współczynniki bezpieczeństwa w przypadku takich urządzeń są bardzo wyśrubowane.
EN
Materials used in the construction of means of transport, and especially in aviation, must offer increased properties, mainly strength, in relation to materials used in the manufacture of other parts of machinery. The safety factors for such devices are very high.
13
Content available remote Modeling and analysis of the stress-strain state of robotic systems
Khayrnasov Kamil
Przegląd Elektrotechniczny
|
2021
|
R. 97, nr 8
66--69
EN
The paper considers the methodology for modeling and analyzing the performance of a robotic system: multi-stage semi-natural simulation stand designed to simulate the flight characteristics of guidance systems in ground conditions. The results of the calculation showed that the use of a composite material gives advantages over the traditionally used materials for the manufacture of such stands: magnesium alloys, due to the high specific strength of the composite material.
PL
W artykule rozważono metodykę modelowania i analizy działania systemu robotycznego: wieloetapowe półnaturalne stanowisko symulacyjne przeznaczone do symulacji charakterystyk lotu systemów naprowadzania w warunkach naziemnych. Wyniki obliczeń wykazały, że zastosowanie materiału kompozytowego daje przewagę nad tradycyjnie stosowanymi materiałami do produkcji takich stojaków: stopami magnezu, ze względu na wysoką wytrzymałość właściwą materiału kompozytowego.
14
Projekt remontu i poszerzenia historycznego mostu im. J. Piłsudskiego przez Wisłę w Toruniu
Wąchalski Krzysztof
Mosty
|
2021
|
nr 1
50--57
PL
W artykule omówiony został projekt remontu mostu im. J. Piłsudskiego w Toruniu. Zastosowano m.in. innowacyjna konstrukcje oraz materiały kompozytowe, co pozwoliło na skrócenie czasu i kosztów remontu.
EN
The article discusses the design of the renovation of the J. Piłsudski bridge in Toruń. An innovative structure and composite materials were used, among others, which allowed to shorten the time and costs of the restoration.
15
Content available Vibroacoustic analysis in the assessment of the technical condition of the aircraft airframe composite elements
Mokrzan Daniel, Milewicz Julia, Szymański Grzegorz M., Szrama Sławomir
Diagnostyka
|
2021
|
Vol. 22, No. 2
11--20
EN
The paper presents the method of assessment of the technical condition of the leading edge of the horizontal stabilizer of an F-16 Block C aircraft made from composite materials. The described method was an experimental measurement of the acoustic pressures generated by the technically operational element and the element with the distorted structural continuity and then a comparison of these pressures in the curves of time and frequency in order to assess how the damage impacts the parameters of the acoustic wave. The test was performed in a dual-channel system, the pressure was induced through impacts on the investigated element with an impact hammer and then, based on the measured induction parameters and the generated acoustic wave, the function of frequency response was calculated, based on which the authors assessed how the structural damage influenced the curve characteristics of the acoustic pressure in the domain of frequency. The described method may be used as an efficient method of non-destructive diagnostics of the airframe elements of an aircraft.
PL
Artykuł przedstawia metodę oceny stanu technicznego krawędzi natarcia statecznika poziomego statku powietrznego F-16 Block C wykonanej z materiałów kompozytowych. Opisywaną metodę stanowił eksperymentalny pomiar ciśnienia akustycznego emitowanego przez element sprawny technicznie oraz element z naruszoną ciągłością struktury, a następnie porównanie ich przebiegu w domenie czasu oraz częstotliwości celem ustalenia w jaki sposób uszkodzenia wpływają na parametry emitowanej fali akustycznej. Badanie dokonywane było dwukanałowo, ciśnienie akustyczne wzbudzane było za pomocą uderzeń w badany element za pomocą młotka modalnego, następnie na podstawie zmierzonych parametrów wzbudzania oraz wywołanego nim fali akustycznej obliczono funkcję odpowiedzi częstotliwości, na podstawie której określono jak uszkodzenie struktury wpływa na przebieg charakterystyki ciśnienia akustycznego w dziedzinie częstotliwości. Opisywana metoda może służyć za skuteczną metodę diagnostyki nieniszczącej elementów płatowca statku powietrznego.
16
Content available remote Investigation of finite element (FE) modelling of composite materials: shell, solid and solid layered composite modelling – comparison of impact on simulation results
Gojny Katarzyna, Dacko Adam
Composites Theory and Practice
|
2021
|
R. 21, nr 1-2
29--39
EN
Composites materials have attracted a great deal of interest for use in various fields e.g. the transport industry, construction, sport equipment and even home applications. This is due to the excellent properties of composite materials such as their high strength/stiffness to mass ratio. Nowadays, finite element (FE) modelling allows investigation of the behaviour of composite materials subjected to loading before the production stage. This paper compares the available ways of FE modelling of composite materials: shell, solid shell and solid layered composite modelling in MSC Patran/Nastran software. The aim of this research work was a comparative analysis and determination of the influence of the applied modelling type on the simulation results. Numerous finite element analyses (FEAs) (tensile and bending) of different narrow plate (resembling a slender, beam-like structural member) structure models were performed, i.e. laminated beam and sandwich beam models, with different layups of layers. The obtained numerical results allow the authors to conclude that shell composite finite element modeling can be considered a practically optimal choice due to reduction of the modelling effort and time, as well as due to obtaining consistent simulation results, especially when having only the basic manufacturer’s set of material constants.
PL
Materiały kompozytowe cieszą się dużym zainteresowaniem w różnych dziedzinach, np. przemysł transportowy, budownictwo, sprzęt sportowy i nawet zastosowania domowe. Wynika to z doskonałych właściwości materiałów kompozytowych, takich jak wysoki stosunek wytrzymałości/sztywności do masy. Obecnie modelowanie metodą elementów skończonych (MES) pozwala na badanie zachowania się materiałów kompozytowych poddanych obciążeniu przed etapem produkcji. W artykule porównano dostępne sposoby modelowania MES materiałów kompozytowych: modelowanie powłokowe, bryłowe i bryłowo-warstwowe w oprogramowaniu MSC Patran/Nastran. Celem pracy badawczej była analiza porównawcza i określenie wpływu zastosowanego modelowania na wyniki symulacji. Przeprowadzono liczne analizy MES (zginanie i rozciąganie) dla różnych modeli wąskiej płyty (przypominającej smukły, belkowy element konstrukcyjny), tj. dla modelu materiału laminatu warstwowego oraz struktury przekładkowej, z różnymi układami warstw. Uzyskane wyniki numeryczne pozwalają stwierdzić, że modelowanie powłokowe materiałów kompozytowych jest praktycznie optymalnym wyborem ze względu na zmniejszenie nakładu pracy i czasu oraz uzyskanie spójnych wyników symulacji, zwłaszcza gdy dysponuje się tylko podstawowym zestawem stałych materiałowych producenta.
17
Content available Improvement of the Mechanical Behavior of Composite Materials with Different Binders Based on Local Plant Fibers Alfa and Diss
Belkhir Zohra, Merzoud Mouloud
Civil and Environmental Engineering Reports
|
2021
|
Vol. 31, no. 4
130--147
EN
Concerned about the environmental and economic impact, composite materials are increasingly used in the construction sector. Indeed, the use of plant fibers as reinforcement in construction materials have been the subject of several researches in recent years; the main motivation is the weight gain combined with high mechanical characteristics. The objective of this research concerns the study of the physicomechanical properties of composite materials with cement and clay matrices reinforced with Alfa and Diss fibers with dimensions ranging from 2 to 8 cm. This involves evaluating the performance of these materials according to the formulation, for a volume ratio (Alfa or Diss / Matrix fibers equal to 4), using dry fibers and pre-wetted fibers. The study of the mechanical properties showed a drop of the performance for both compression and bending strength compared to the reference material without adding fibers (cement or clay paste). It should be noted that the best mechanical performance is obtained for the case of composites materials with cementitious matrix with pre-wetted fibers. On the other hand, in the case of composites with clayey matrices, pre-wetting does not improve the mechanical characteristics. It is also noted that the best dimensions of fibers which improve the mechanical characteristics in bending are generally 6 cm for composites with a clay matrix and between 2 and 4 cm for cementitious composites. In all cases, the fibers in composite materials with cement or clay matrix create a bridging effect, making it possible to limit the progression of cracks during loading. This phenomenon gives to the various composite materials a ductile behavior.
18
Content available Energy balance modelling of high velocity impact effect on composite plate structures
Al-Waily M., Jaafar A.M.
Archives of Materials Science and Engineering
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2021
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Vol. 111, nr 1
14--33
EN
Purpose: In many military applications, composite materials have been used because of their high velocity impact resistance that helps absorption and dispersion energy. It is therefore used in armour and vehicles, aircraft and spacecraft that are subjected to impact of various shapes and velocities. Design/methodology/approach: In the theoretical part, the absorption energy equation for the sample was established by constructing an energy balance equation consisting of five types of energies, it is the compressive energy in the first region (the impact region), the tensile energy in the first region, the tensile energy in the second region, the energy of the shear plugging and the friction energy. Findings: It was found in the experiments that the tensile stress value increased by increasing the volume fraction of fibres to the polyester, and the value of compressive stress decreased. Also manufactured different types of impact samples with dimensions (20*20 cm2 ) and deferent thickness. The results were an increase in the amount of energy absorbed by increasing the ratio of the fibre to the polyester. It is found that the greatest effect in the equation of energy balance is the shear plugging energy, in which the value of the energy absorbed reached 38% of the total energy. And in the second degree friction energy, in which the value of the energy absorbed reached 27% of the total energy. while the other energies are relatively small but with important values, except for the tensile energy in the second region, the Kevlar-Polyester (40-60)%, so that the increase was more than four times the previous case. Research limitations/implications: Three types of reinforcing fibres were used: Kevlar, Carbon and Glass fibres with a matrix material as polyester. Six samples are made for tensile and compression testing, Kevlar-Polyester (30-70)%, Carbon-Polyester (30-70)%, Glass-Polyester (30-70)%, Kevlar-Polyester (40-60)%, Carbon-Polyester (40-60)% and Glass-Polyester (40-60)%. Practical implications: On the experimental part, experimental work tests were carried out to determine the mechanical properties of the samples such as tensile and compression tests as well as conducting the natural frequency test conducting the impact test by bullet to identify the effects and penetration incidence and compare this with the theoretical results. Originality/value: In this research high velocity impact is used with a bullet it diameter 9 mm, mass of 8 g, and a semi-circular projectile head with a specific velocity ranging from 210-365 m/s. The effect of the impact is studied theoretically and experimentally. The elastic deformation is increased for increasing the ratio of the fiber to the polyester and the depth of penetration is decreasing. The hybrid sample is affected in absorption energy and decreasing the penetration. Finally calculated for penetration behaviour theoretically and experimentally for different composite materials and comparison for the results calculated.
19
Content available Microsegregation of Elements in Steel Composite Reinforced with Ceramic
Medyński D., Janus A. J.
Archives of Foundry Engineering
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2021
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Vol. 21, iss. 1
63--66
EN
The paper presents results of research on steel castings GX120Mn13 (L120G13 by PN-89/H-83160), zone-reinforced by elektrocorundum particles (Al2O3), with a grain size from 2 to 3.5 mm. Studies revealed continuity at interface between composite components and formation of a diffusion zone in the surface layer of electrocorundum grains. In the area of this zone, simple manganese segregation and reverse iron and chromium segregation were found. The transfer of these elements from cast steel to electrocorundum grains resulted superficial depletion in aluminum and oxygen in this area. No porosity was observed at the interface between two components of the composite. We found it very beneficial from an exploitation point of view, as confirmed by the study of resistance to abrasive wear.
20
Content available Assessment of the Possibility of Using Fractal Analysis to Describe the Surface Aluminum Composites After Turning
Karolczak P., Kowalski M., Raszka K.
Advances in Science and Technology. Research Journal
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2021
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Vol. 15, no 4
49--60
EN
The description of the characteristics of the surface using standardized roughness parameters can not fully predict its performance properties. One of the tools supporting the assessment of the surface layer of the treated surface may be fractal analysis. This applies both to surfaces with machining traces, which are created under conditions of high randomness and variability of process conditions, and to surfaces with directional traces and their distinct periodicity. The paper presents the results of surface roughness measurements of turned aluminium matrix composites reinforced with ceramic fibers. Carbide and diamond tools were used for turning the tested material. The trials were carried out under dry machining conditions and with minimal lubrication in the cutting zone. Surfaces were measured by the contact method, and surface roughness parameters were calculated by Gaussian filtration. Then, the values of the fractal dimension were calculated using the enclosing box method. On the basis of these calculations, the influence of machining conditions on the values of selected roughness parameters and the box fractal dimension was determined. It was found that the fractal dimension, i.e. the irregularity of the geometric structure of the surface after turning of composites, changes with the change of cutting parameters, the tool and the method of lubricating the cutting zone. Of these factors, the feed has the greatest influence. As it grows, the irregularity of the machined surface structure decreases. In addition, the correlation coefficients between the fractal dimension and the measured roughness parameters were determined. It was noticed that the fractal dimension, in the case of turning aluminum composites, best correlates with the roughness parameters Sa and Ssk and thus describes features similar to these parameters. Therefore, it was assumed that it is possible to use fractal analysis as a supplementary tool for the description of the surface condition of aluminum composites after turning in various machining conditions. On the other hand, the fractal dimension can be treated as an additional tool to describe the surface condition, especially its irregularity, which is not described by other standard roughness parameters.
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