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1

Comparative evaluation of mechanical properties of short aramid fiber on thermoplastic polymers

Arı Ali, Bayram Ali, Karahan Mehmet, Arslan Orhun

Materials Science Poland

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2023

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Vol. 41, No. 1

161--176

EN

This study investigated the mechanical performance of short aramid fiber on polypropylene, polyethylene, polyamide 6, and polyamide 12. Extrusion, press molding, and CNC cutting methods were used in the production of composite samples. Tensile, three-point bending, drop weight and hardness tests of the composites were carried out. As the fiber volume fractions increased, the mechanical properties of the composites improved, but the most efficient fiber fractions for each matrix changed. To analyze the performance of the fibers in the matrix on the composites, scanning electron microscope (SEM) images of the fractured surfaces as a result of tensile and drop weight tests were examined. As the fiber volume fractions increased, the fiber deformation increased, and as a result, the mechanical performance of the composites was adversely affected. Analysis of variance (ANOVA) and F test were performed using signal/noise values to analyze in detail the effect of experimental parameters on output values. Finally, the results of a regression equation model were compared with the experimental readings. It was found to be in good agreement with the model and the results of the experiment.

2

Fatigue tests, self-healing of polymer-matrix composites in unmanned aerial vehicles

Augustyn S., Kowalski R.

Journal of KONBiN

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2018

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No. 48

83--106

EN

This publication presented the main issues related to fatigue of polymer composite materials. It was featured a fatigue stress test based on composite sample, made of carbon fiber-reinforced polymer, using the four-point bending method. The test was carried out with the initial load and using positive load cycles. The perspectives of diagnostics and self-healing of composite materials, including intelligent materials, were also presented.

PL

W publikacji przedstawiono kluczowe zagadnienia dotyczące zjawiska zmęczenia polimerowych materiałów kompozytowych. Omówiono próbę zmęczeniowego obciążenia próbki, wykonanej z materiału kompozytowego wzmacnianego tkaniną węglową o osnowie polimerowej, przy wykorzystaniu metody zginania czteropunktowego. Doświadczenie wykonane zostało przy wstępnym obciążeniu próbki oraz zastosowaniu cykli jednostronnych dodatnich. Przedstawiono również perspektywy rozwoju diagnostyki i samonaprawy zmęczeniowej materiałów kompozytowych, z uwzględnieniem materiałów inteligentnych

3

Composite sandwich footbridge – numerical ESL FEM calculations vs. In situ measurements

Miśkiewicz M., Chróścielewski J., Sobczyk B., Pyrzowski Ł.

Engineering Transactions

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2017

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Vol. 65, iss. 1

77--82

EN

Selected results of the static analysis of composite sandwich footbridge with the corresponding in situ measured values are compared in the paper. The analysed bridge is a research object, which was built in 2015 and is currently located at the Gdańsk University of Technology campus. Since it is a novel structure, a proper definition of the bridge numerical model, allowing its safe design, is very important. Therefore, instead of some preliminary research, carried out on sandwich beams or the bridge segment, also the calculated structural properties of the full scale object should match the experimentally predicted response. This verification was required to obtain permission for the bridge exploitation, according to the government regulations.

4

Numerical and Experimental Analysis for Shape Improvement of a Cruciform Composite Laminates Specimen

Gutiérrez J. C., Lozano A., Manzano A., Flores M. S.

Fibres & Textiles in Eastern Europe

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2016

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Vol. 24, no. 2 (116)

89--94

EN

The use of composite materials has spread to different applications among which, those using thin sheet plates subjected to biaxial loads are commonly used in the car and aerospace industries. Hence, there is need of a reliable specimen to test these materials under biaxial loads. This reliability depends on measurements that are accurate and repeatable. Thus these measurements depend on the proper design of specimens. This paper reviews the development of cruciform specimens of carbon fibre composite materials and how the geometric shape has evolved. Based on this review, a new geometric shape is proposed. This improvement is based on numerical analysis of the specimen and tests results of experimental measurements carried out using a four piston rig in an orthogonal arrangement. Deformation is measured in the centre of the specimen using strain gauges. By obtaining the principal stresses, it was found that maximum stresses occur in the centre of the specimen.

PL

Powszechnie stosowane są kompozyty poddawane testom dwuosiowym. Prawidłowe przeprowadzenie tego rodzaju testów jest trudne biorąc pod uwagę rozkład naprężeń badanych w próbce. Omówiono szereg struktur stosowanych dla uzyskania wyników dokładnych i powtarzalnych. Przeprowadzono analizę poprawy kształtu próbki rozpatrując laminat z udziałem włókien węglowych i żywicy epoksydowej. Przeprowadzono testy rozciągania dwuosiowego. Odkształcenia mierzono w centralnej części próbki stosując specjalne czujniki przesunięcia. Stwierdzono, że maksymalne naprężenia występują w środku próbki.

5

Determination of material parameters for microbuckling analysis of fiber reinforced polymer matrix composites

Romanowicz M.

International Journal of Applied Mechanics and Engineering

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2015

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Vol. 20, no. 2

373--383

EN

This research focuses on studying the effect of the constitutive law adopted for a matrix material on the compressive response of a unidirectional fiber reinforced polymer matrix composite. To investigate this effect, a periodic unit cell model of a unidirectional composite with an initial fiber waviness and inelastic behavior of the matrix was used. The sensitivity of the compressive strength to the hydrostatic pressure, the flow rule and the fiber misalignment angle were presented. The model was verified against an analytical solution and experimental data. Results of this study indicate that a micromechanical model with correctly identified material parameters provides a useful alternative to theoretical models and experimentation.

6

Development of active composite aerofoil for assessment of novel flow control concepts

Koschichow R., Holeczek K., Koschichow D., Rüdiger F., Kostka P., Langkamp A., Fröhlich J., Modler N.

Composites Theory and Practice

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2015

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R. 15, nr 3

146--151

EN

In this paper, an investigation of the dynamic effects of the low-amplitude, high-frequency excitation of a composite aerofoil by means of integrated actuators on the flow is presented. For this purpose, a well-established elastic NACA 64-418 profile was manufactured from a glass fibre reinforced epoxy resin with integrated active elements. The modal properties of the profile were optimized during the design process in such a way that the spatial distribution of nodes and antinodes of the profile is potentially advantageous for the influence of the flow behaviour around the profile. Additionally, the respective eigenfrequency of the profile should be high enough to efficiently influence the flow. The first numerical and experimental results confirm that the aimed modal properties could be obtained. The optimized profile design has been implemented in the resin transfer moulding manufacturing process and selected low-profile actuating elements were applied after fibre-reinforced plastics consolidation on the inner surface of the NACA profile. The applicability of the proposed flow control approach will be evaluated in detail in a specially developed flow channel in further investigations.

PL

W pracy przedstawiono badania dynamicznego wpływu niskoamplitudowego, wysokoczęstotliwościowego pobudzenia za pomocą zintegrowanych w kompozytowy profil lotniczy elementów wykonawczych na opływające profil medium. W tym celu dobrze poznane profile typu NACA 64-418 zostały wytworzone z materiału kompozytowego na bazie żywicy epoksydowej wzmocnionej włóknami szklanych i wyposażone w zintegrowane elementy wykonawcze. Parametry modalne profili zoptymalizowano w procesie projektowania w taki sposób, iż przestrzenne rozmieszczenie węzłów i strzałek profilu ma potencjalnie korzystny wpływ na opływające go medium. Dodatkowo, odpowiadająca tej postaci częstotliwość własna profilu musi być wystarczająco wysoka, aby efektywnie wpływać na przepływ. Pierwsze numeryczne i eksperymentalne wyniki potwierdzają możliwość uzyskania zamierzonych parametrów modalnych. Do wytworzenia zoptymalizowanej konstrukcji profilu wykorzystano technologię RTM (ang. Resin Transfer Moulding). Po skonsolidowaniu profilu wybrane cienkie elementy wykonawcze zostały zaaplikowane na wewnętrznej powierzchni profilu NACA. Możliwość zastosowania proponowanego podejścia do kontroli przepływu medium będzie określana szczegółowo w dalszych badaniach w specjalnie skonstruowanym kanale przepływowym.

7

Numerical identification of material parameters for microbuckling analysis of fiber reinforced polymer matrix composites

Romanowicz M.

Computer Methods in Materials Science

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2014

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Vol. 14, No. 2

108--113

EN

This research focuses on studying the effect of material parameters upon the compressive response of a unidirectional fiber reinforced polymer matrix composite. To investigate this effect, the finite element method and a periodic unit cell model of unidirectional composite with an initial fiber waviness and inelastic behavior of the matrix were used. The sensitivity of the compressive strength to the hydrostatic pressure, the flow rule and the fiber misalignment angle were presented. The model was verified against an analytical solution and experimental data. The results of this study indicate that a micromechanical model with correctly identified material parameters provides a useful alternative to theoretical models and experimentation.

PL

W pracy badano wpływ parametrów materiałowych na wytrzymałość na wzdłużne ściskanie kompozytu jednokierunkowo wzmocnionego. W tym celu wykorzystano metodę elementów skończonych oraz komórkę elementarną kompozytu z początkową imperfekcją włókien i plastyczną matrycą. Analizowano zmianę krzywej ściskania kompozytu w wyniku zmiany tarcia wewnętrznego matrycy, prawa plastycznego płynięcia matrycy oraz początkowej imperfekcji włókien. W celu identyfikacji wymienionych parametrów materiałowych wykorzystano badania doświadczalne oraz istniejące modele analityczne. Wyniki badań pokazują, że model numeryczny jest skuteczną alternatywą w analizie mikro-wyboczenia kompozytów polimerowych wzmocnionych ciągłym włóknem.

8

Improving Sound Absorption Property of Polyurethane Foams by Adding Tea-Leaf Fibers

Ekici B., Kentli A., Kücük H.

Archives of Acoustics

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2012

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Vol. 37, No. 4

515-520

EN

The sound absorption property of polyurethane (PU) foams loaded with natural tea-leaf fibers and luffa cylindrica (LC) has been studied. The results show a significant improvement in the sound absorption property parallel to an increase in the amount of tea-leaf fibers (TLF). Using luffa-cylindrica as a filler material improves sound absorption properties of soft foam at all frequency ranges. Moreover, an increase in the thickness of the sample resulted in an improvement of the sound absorption property. It is pleasing to see that adding tea-leaf fibers and luffa-cylindrica to the polyurethane foam demonstrate a significant contribution to sound absorption properties of the material and it encourages using environmental friendly products as sound absorption material in further studies.