Wyniki wyszukiwania - BazTech

1

A proposed approach to predict the longitudinal and transverse electrical conductivity of CFRP materials

Zeghdoud Zakaria, Bouloudenine Abderraouf, Latreche Mohamed El Hadi, Javaid Muhammad Sharjeel, Bouchekara Houssem Rafik El-Hana

Przegląd Elektrotechniczny

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2026

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R. 102, nr 2

85--92

EN

The objective of this study is to predict the longitudinal and transverse electrical conductivities of unidirectional carbon fiber-reinforced polymers through the coupling of an algebraic matrix with experimental parameters. Initially, regular hexagonal topology structures are generated for various filling rates. These structures, in conjunction with the experimental parameters of CFRP, are utilized to create a comprehensive algebraic matrix. Subsequently, two specific sub-matrices, derived from this global matrix, are employed to predict electrical conductivities. At a filling rate of 59%, the obtained longitudinal conductivity reaches a value of 37 kS/m, while the transverse conductivity is recorded as 14 S/m. These findings confirm the strong predictive computational efficiency of the algebraic matrix approach, highlighting its potential for applications in smart structures and structural health monitoring.

PL

Celem tego badania jest przewidywanie wzdłużnych i poprzecznych przewodności elektrycznych jednokierunko- wych polimerów wzmacnianych włóknami węglowymi poprzez sprzężenie macierzy algebraicznej z parametrami eksperymen- talnymi. Początkowo generowane są regularne struktury topologii heksagonalnej dla różnych szybkości napełniania. Struktury te, w połączeniu z parametrami eksperymentalnymi CFRP, są wykorzystywane do tworzenia kompleksowej macierzy algebraicznej. Następnie, dwie określone podmacierze, pochodzące z tej globalnej macierzy, są wykorzystywane do przewidywania przewodności elektrycznych. Przy stopniu wypełnienia 59% uzyskano przewodność podłużną na poziomie 37 kS/m, a przewodność poprzeczną na poziomie 14 S/m. Odkrycia te potwierdzają wysoką wydajność predykcyjną podejścia macierzowego, podkreśla- jąc jego potencjał w zastosowaniach w inteligentnych konstrukcjach i monitorowaniu stanu konstrukcji.

2

Hybrid polymer materials with substantially improved mechanical properties

Sanocki Tadeusz, Sanocki Marek, Sanocka-Zajdel Agnieszka, Majcherczyk Henryk, Zajdel Magdalena, Bulanda Katarzyna, Oliwa Rafał, Oleksy Mariusz, Budzik Grzegorz, Stącel Monika

Polimery

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2025

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Vol. 70, nr 3

194--203

EN

The results of the research project POIR.01.01.01-00-0760/18 implemented from the funds of the Smart Growth Operational Program in the years 2014-2020 entitled “Development of a new technology for manufacturing details from polymer materials with significantly improved mechanical and visual properties” at Splast Ltd. were presented. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to assess the structure of the composites. The strongest interactions at the composite-coating interface were observed in the case of the use of varnish (interphase boundary width). The composites were characterized by gloss in the range of 32.6-448 GU, which classifies them as semi-gloss or glossy materials. SEM micrographs confirmed the correctness of the selection of materials, as evidenced by good fiber dispersion in the polymer matrix, while maintaining a characteristic round shape.

PL

Przedstawiono wyniki badań projektu POIR.01.01.01-00-0760/18 realizowanego ze środków Programu Operacyjnego Inteligentny Rozwój w latach 2014-2020 pt. „Opracowanie nowej technologii wytwarzania detali z materiałów polimerowych o znacząco poprawionych właściwościach mechanicznych i wizualnych” w Splast Sp. z o.o. Do oceny struktury kompozytów użyto mikroskopię sił atomowych (AFM) i skaningową mikroskopię elektronową (SEM). Najsilniejsze oddziaływania na granicy faz kompozyt-powłoka zaobserwowano w przypadku zastosowania powłoki lakierniczej (szerokość granicy międzyfazowej). Kompozyty charakteryzowały się połyskiem w zakresie 32,6-448 GU, co klasyfikuje je jako materiały z półpołyskiem lub połyskiem. Mikrofotografie SEM potwierdziły poprawność doboru materiałów, o czym świadczy dobra dyspersja włókna w osnowie polimerowej, przy zachowaniu charakterystycznego okrągłego kształtu.

3

Zastosowanie cyfrowej korelacji obrazu do analizy pola przemieszczeń stalowych belek cienkościennych typu sigma wzmacnianych tkaniną z włókna węglowego

Rzeszut Katarzyna, Dybizbański Maciej Adam

Inżynieria i Budownictwo

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2025

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R. 81, nr 3

282--292

PL

W niniejszej pracy przedstawiono wyniki badań laboratoryjnych przeprowadzonych metodą cyfrowej korelacji obrazu ARAMIS 6M. Pomiar przemieszczeń oraz ocena deformacji została przeprowadzona dla belek CFS o przekroju Σ200×70×2 i rozpiętości 2700 mm, wykonanych ze stali S350GD. Testy czteropunktowego zginania przeprowadzono dla belek wzmocnionych i niewzmocnionych (belki referencyjne). Wzmocnienie wykonano przy użyciu tkaniny SikaWrap 230 C przyklejonej do zagięć brzegowych klejem SikaDur 330. Badania przeprowadzono dla dwóch przypadków: dla podpór z możliwością deplanacji przekroju i dla podpór ze skrępowaną deplanacją. Na podstawie uzyskanych wyników stwierdzono, że zarówno w przypadku przemieszczeń pionowych, jak i poziomych zastosowanie zaproponowanego wzmocnienia ma szczególnie korzystny wpływ wówczas, gdy na podporach nie ma możliwości deplanacji przekroju.

EN

This paper presents the results of laboratory tests obtained using the ARAMIS 6M digital image correlation method. The displacement measurement and deformation assessment were carried out for CFS beams with a cross-section of Σ200×70×2 and a span of 2700 mm, made of S350GD steel, reinforced and unreinforced (reference), loaded in a four-point bending scheme. The beams were reinforced with SikaWrap 230 C fabric glued to the edge stiffeners using SikaDur 330 adhesive. The tests were carried out for two cases, i.e., with the possibility of cross-section deplanation at the supports and for the lack of deplanation at the supports. Based on the obtained results, it was found that in the case of vertical and horizontal displacements, the use of the proposed reinforcement has a particularly beneficial effect for the case when there is no possibility of cross-section deplanation at the supports.

4

Studying the metakaolin content, fiber type, and high-temperature effects on the physico-mechanical properties of fly ash-based geopolymer composites

Bayrak Bariş, Alcan Haluk Görkem, Durmaz Özge Çiğdem Özelmacı, ipek Süleyman, Kaplan Gökhan, Güneyisi Erhan, Aydın Abdulkadir Cüneyt

Archives of Civil and Mechanical Engineering

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2025

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Vol. 25, no. 1

art. no. e2, 2025

EN

The study investigated the physicasl characteristics and mechanical performance of fly ash-based geopolymer composites when exposed to high temperatures. Geopolymer composites were produced using fly ash as an aluminosilicate-rich raw material and a combination of sodium silicate and sodium hydroxide as an alkaline activator. In this context, the study also examined the impact of partially replacing metakaolin (7.5% and 15% by weight). Furthermore, the study aims to examine the impact of adding fiber (basalt and carbon types) on the physical, mechanical, and high-temperature properties of geopolymer composites. The physical properties investigated were unit weight, apparent porosity, water absorption, and capillary water absorption, while the strength performances investigated were flexural and compressive strengths. To monitor the effect of high temperatures on the strength characteristics of the geopolymer composites, the mixtures were exposed to temperatures of 200 °C, 400 °C, and 600 °C. Besides, SEM images were provided to illustrate the degree of geopolimerization. The results indicated that metakaolin replacement yielded mixtures having higher unit weight, but lower apparent porosity and water absorption. The results indicated that metakaolin replacement yielded mixtures having a higher unit weight, reaching an increase of about 5%, but lower apparent porosity and water absorption, with decreases reaching 18.3% and 20%, respectively. The metakaolin-blended geopolymer composites resulted in better strength performance and resistance to high temperatures. Raising the metakaolin replacement level from 0 to 15% led to an increase of 17.3% in flexural strength. The compressive strength of the composites subjected to a temperature of 200 °C exhibited an increase of over 10%. Notably, this rate of increment was observed to be nearly 20% higher in nonfibrous composites. Fiber addition decreased the compressive strength up to about 21%, while increasing the flexural strength up to 65%. Strength performance improved at 200 °C, but decreased at higher temperatures up to 600 °C. The geopolymer composites experienced significant mass loss when exposed to high temperatures.

5

Porównanie ugięcia betonowych belek zbrojonych prętami GFRP, BFRP i ze stali B500

Pytlowany Tomasz, Leń Dariusz, Piszczek Kazimierz, Zimka Roman

Przegląd Budowlany

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2024

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R. 95, nr 1-2

77--80

PL

Głównym celem badań było uzyskanie danych związanych z jakościową oceną sztywności belek betonowych zbrojonych prętami stalowymi EPSTAL B500SP oraz kompozytowymi prętami zbrojeniowymi GFRP i BFRP przy zachowaniu tego samego stopnia zbrojenia belek. Przyjęto schemat statyczny badanych elementów w postaci belki swobodnie podpartej o rozpiętości 1,5 m. Podstawowym opisem zachowania badanych elementów, zarejestrowanym podczas badań, była ścieżka równowagi statycznej opisana w układzie współrzędnych: siła obciążająca P i ugięcie belki u, rejestrowane za pomocą czujników, zarejestrowane zależności P-u. Podane na wykresach wartości ugięcia belek u są średnią arytmetyczną pomiarów z czujników przemieszczenia. W trakcie badań wykonano również pomiary odkształceń prętów zbrojeniowych w zależności od wartości przyłożonego obciążenia P. Wyniki tych pomiarów przedstawiono graficznie.

EN

The main purpose of the research was to obtain data related to the qualitative assessment of the stiffness of concrete beams reinforced with B500SP EPSTAL steel reinforcement bars and GFRP and BFRP composite reinforcing bars while maintaining the same degree of reinforcement of the beams. A static scheme of the tested elements was adopted in the form of a simply supported beam with a span of 1,5 m. The basic description of the behavior of the tested elements, recorded during the tests, was the static equilibrium path described in the coordinate system: loading force P and beam deflection u, recorded using sensors, the recorded P-u dependencies. The deflection values of the beams u given in the graphs are the arithmetic mean of the measurements from the displacement sensors. During the tests, measurements of reinforcing bars deformation were also carried out depending on the value of the applied load P. The results of these measurements are presented graphically.

6

Experimental of buckling restrained brace hysteretic performance with carbon fiber wrapped in concrete

Fang Yuan, Lv Lei, Gao Yuqiang, Fu Zhongqiu

Archives of Civil Engineering

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2024

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Vol. 70, nr 1

527--541

EN

Buckling restrained brace is an important structure for improving the seismic resistance of structures. Conducting research on new types of buckling restrained brace can improve the seismic performance and reliability of buckling resistant support. Four different types of buckling restrained braces specimens were designed and manufactured: cross-shaped square steel pipe members, cross-shaped round steel pipe members, cross-shaped carbon fiber members, and in-line carbon fiber members. By conducting quasi-static tests, the force displacement hysteresis curves, skeleton curves, stiffness degradation, equivalent viscous damping coefficient, and energy dissipation ratio of four different types of buckling restrained brace were analyzed. The research results showed that all four buckling restrained brace specimens have good hysteresis performance. The load-bearing capacity and energy consumption performance of the three specimens of square steel pipe, round steel pipe and carbon fiber with the same core unit are the same, but the inline type is worse than the cross type. The core unit specimen with a width of 80 mm is about 60% higher in bearing capacity and energy consumption than a specimen with a width of 50 mm. The core unit of some specimens undergoes multi-wave buckling. For carbon fiber specimens, the CFRP is prone to breakage due to the lateral thrust of the restraining unit. Therefore, steel hoop or stirrup should be added to the end to improve the restraint effect when designing and manufacturing.

7

Experimental and theoretical study on the shear behavior of CFRP bar‑reinforced UHPFRC beams considering orientation and volume fraction of steel fibers

Liang Longming, Ke Lu, Feng Zheng, Li Chuanxi, Yan Banfu, Guo Jia

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 1

art. no. e1, 2024

EN

This paper aims to comprehensively understand the shear behavior of fiber-reinforced polymer (CFRP) bars reinforced ultra-high-performance fiber-reinforced concrete (UHPFRC) beams, and develop a calculation model to predict the shear capacity. The crucial parameters under consideration are the orientation and volume fraction of steel fibers. A magnetic field fiber orientation setup was utilized to achieve the desired orientation. The results indicated that all UHPFRC beams demonstrated shear failure, showing clear instances of both beam action and arch action throughout the failure progression. By orienting the steel fibers at an angle of 60° relative to the longitudinal axis of the beams, the average shear capacity increases by 23.51% compared to that of the beams with random distributed steel fibers because the steel fibers are almost perpendicular to the diagonal shear cracks. Increasing the fiber volume fraction from 1.5% to 2.0% led to a significant maximum increase in the average shear capacity, reaching 31.73%. Moreover, the larger orientation angles and higher volume fraction of steel fibers contributed to improved ductility, reaching a maximum of 124.0%. Finally, a highly accurate model based on the fiber-matrix discrete approach was formulated. The proposed model showed a slight overestimation of shear capacity, with most values not exceeding 10%, and a standard deviation below 6.22%.

8

Structural integrity of three dimensional printed carbon fiber composites/nanocomposites for aeronautical components—current scenarios and opportunities

Kausar Ayesha

Advances in Materials Science

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2024

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Vol. 24, nr 4(82)

67--97

EN

This state-of-the-art innovatory overview essentially debates practical worth of three-dimensional printed composites/nanocomposites (especially carbon fiber designs) for aerospace sector. Recently, three-dimensional printing (additive manufacturing) has competently transpired for designing high performance space structures. The manuscript systematically frameworks fundamentals of three-dimensional printing approach, ensuing high-tech aeronautical carbon fiber composites/nanocomposite systems, and space components/structural applications. Amongst carbonaceous fillers, short/continuous carbon fibers were inspected as outperforming reinforcements for aerospace. Additionally, surface modified/composited carbon fibers with nanocarbons (carbon nanotube, graphene) have been reported. Accordingly, polyamide, poly(lactic acid), poly(ether ether ketone), epoxies, etc. have been documented as substantial thermoplastic/thermosetting matrices. Ensuing radical polymer/carbon fiber or polymer/carbon fiber/nanocarbon hybrids have benefits regarding low-cost manufacturing, structural precision, complex geometries, high efficiency, least structural defects/voids, superior tensile and shear strength/modulus, compression strength, interlaminar strength, wear properties, thermo-dimensional constancy, and heat stability features, under extreme space environments. Consequently, cutting-edge three-dimensional printed carbon fiber hybrids offered myriad of promising opportunities for mechanically robust (nozzle wearing, strengthened wing spar/ribs, resilient rotating components, interlaminar strength/dimensional stability) and high temperature stable (cryogenic fuel storage, lower earth orbital stability, thermal-dimensional steadiness, thermal conductivity) for aerospace modules. Henceforth, three-dimensional printing owns enormous engineering potential to meet aeronautical manufacturing demands by overcoming challenges of traditional techniques.

9

Nanocomposites of nanocarbon functionalized carbon fibers — manufacturing to methodological applications

Kausar Ayesha, Ahmad Ishaq

Advances in Materials Science

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2024

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Vol. 24, nr 1(79)

46--71

EN

Carbon fibers have been technically applied in high performance materials and industrial scale applications. Importantly, carbon fiber reinforced composite materials have found applications in aerospace industries. These properties of carbon fiber reinforced composites depend upon the carbon fiber features such as length, orientation, surface properties, adhesion with matrices, etc. To improve the surface properties of carbon fibers and adhesion and interactions with polymers, fiber modification has been suggested as an efficient approach. Carbon nanoparticle or nanocarbon functionalized carbon fibers have been manufactured using various facile physical and chemical approaches such as electrospraying, electrophoretic deposition, chemical vapor deposition, etc. Consequently, the modified carbon fibers have nanocarbon nanoparticles such as graphene, carbon nanotube, nanodiamond, fullerene, and other nanocarbons deposited on the fiber surface. These nanocarbon nanoparticles have fine capability to improve interfacial linking of carbon fibers with the polymer matrices. The chemical vapor deposition has been adopted for uniform deposition of nanocarbon on carbon fibers and chemical methods involving physical or chemical modification have also been frequently used. The resulting advanced epoxy/carbon fiber/nanocarbon composites revealed improved tensile and physical profiles. This review basically aims manufacturing and technical aspects of polymer/fiber/nanofiller nanocomposites toward the development of high performance structures. The resulting morphology, strength, modulus, toughness, thermal stability, and other physical features of the nanocarbon functionalized carbon fibers have been enhanced. In addition, the fabricated polymer/fiber/nanofiller nanocomposites have fine interfacial adhesion, matrix-nanofiller-filler compatibility, and other characteristics. The application areas of these nanomaterials have been found wide ranging including the strengthened engineering structures, supercapacitors, shape memory materials, and several others.

10

Competence of carbonaceous fibers/nanofillers (graphene, carbon nanotube) reinforced shape memory composites/nanocomposites towards aerospace — existent status and expansions

Kausar Ayesha

Advances in Materials Science

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2024

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Vol. 24, nr 3(81)

30--55

EN

Shape memory or stimuli responsive polymers have established a unique grouping of smart materials. The technical merit of these polymers has been evaluated in aerospace sector, since last few decades. Particularly, the stimuli responsive polymers render inherent competences to recuperate the structural damages in exterior/interior space architectures. In this context, both the thermoplastics as well as thermosetting polymers depicted essential stimuli responsive behaviour. As interpreted in this state-of the-art review, the carbonaceous reinforcement like carbon fibers and nano-reinforcements including nanocarbons (graphene, carbon nanotube) have been employed in the shape recovering matrices. The performance of ensuing shape retrieving aerospace materials was seemed to be reliant on the polymer chain crosslinking effects, filler/nanofiller dispersal/alignment, microstructural specs, interfacial contour and interactions, and processing techniques used. Consequently, the shape actuations of polymer/carbon fiber composites were found to be instigated and upgraded through the inclusion of nanocarbon nano-additives. The ensuing high-tech shape memory composites/nanocomposites have anomalous significance for various aero-structural units (fuselage, wings, antennas, engines, etc.) due to prevention of possible thermal/shock/impact damages. Future implications of carbonaceous shape memory composites/nanocomposites in aerospace demands minimizing the structure-property-performance challenges and large scale fabrication for industrial scale utilizations. In this way, deployment of carbonaceous nanofiller/filler based composites revealed enormous worth due to low density, anti-fatigue/wear, anti-corrosion, non-flammability, self-healing, and extended durability and long life operations. However, there are certain challenges associated with the use of nanocarbons and ensuing nanocomposites in this field markedly the adoption of appropriate carbon fiber coating technique, aggregation aptitude of nanocarbons, additional processing steps/cost, nanoparticle initiated invisible defects/voids, difficulty in machinability operations due to presence of nanoparticles, and corrosion risk of composite structures in contact with metal surfaces. By overcoming these hinderances, nanoparticles modified carbon fiber based composites can be promising towards a new look of upcoming modernized aerospace industry.

11

Wykorzystanie zielonych nanomateriałów w budowie stadionów sportowych

Wei Lixin

Przemysł Chemiczny

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2023

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T. 102, nr 12

1367--1370

PL

Dodanie wielościennych nanorurek węglowych (0,04% mas.) i dodecylobenzenosulfonianu sodu (0,4% mas.) do wodnej zawiesiny fosfogipsu budowlanego, a następnie jego obróbka ultradźwiękowa prowadzona przez 60 min w celu rozproszenia zawiesiny spowodowała wzrost adiabatycznej wytrzymałości na zginanie i adiabatycznej wytrzymałości na ściskanie do odpowiednio 5,04 MPa i 17,55 MPa. Mikrostrukturę gipsu badano za pomocą skaningowej mikroskopii elektronowej. Ulepszone właściwości mechaniczne gipsu mogą być wykorzystane przy budowie stadionów sportowych.

EN

The addn. of multi-walled C nanotubes (0.04% by mass) and Na dodecylbenzenesulfonate (0.4% by mass) to the aq. slurry of P building gypsum and subsequent ultrasonic treatment for dispersing the slurry for 60 min resulted in increasing adiabatic flexural strength and adiabatic compressive strength of the gypsum up to of 5.04 MPa and 17.55 MPa, resp. Microstructure of the gypsum was studied by scanning electron microscopy. The improved mech. properties of the gypsum were of advantage in construction of sport stadiums.

12

Nowe nanomateriały do konstrukcji sprzętu sportowego

Jifang Yuan, Jianguo Chen, Yong Xu

Przemysł Chemiczny

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2023

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T. 102, nr 8

783--794

PL

Nowe nanomateriały dla sprzętu sportowego zostały przygotowane poprzez wzmocnienie żywicy epoksydowej (EP) włóknami węglowymi (CF) i/lub nanorurkami węglowymi (CNT) w celu poprawy jakości, twardości, plastyczności i odporności na starzenie materiałów kompozytowych. CNT zostały równomiernie rozmieszczone poprzez filtrację próżniową i fizyczne osadzanie na powierzchni włókien CF. Wytrzymałość na zginanie kompozytów CF/EP-CNT była o 28,08% większa niż niemodyfikowanego kompozytu CF/EP. Po starzeniu w temp. 120°C naprężenia w kompozycie zostały rozproszone ze względu na doskonałą dyspergowalność CNT, a tłumienie długich pęknięć spowodowało zmniejszenie obszaru uszkodzenia.

EN

New nanomaterials for sport equipment were prepd. by reinforcing an epoxy resin (EP) with C fibers (CF) and/or C nanotubes (CNT) to improve quality, hardness, plasticity and aging resistance of the composite materials. The CNT were uniformly dispersed by vacuum filtration and phys. deposition on CF fiber surface. The bending strength of CF/EP-CNT composites was by 28.08% higher than that of an unmodified CF/EP composite. After aging at 120°C, the stress in the composite was dispersed due to the excellent dispersibility of CNT, and the suppression of long cracks resulted in a redn. of damage area.

13

Functionalization methods of carbon fibers – an overview

Magdziarz Sylwia, Frączyk Justyna, Boguń Maciej

Polimery

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2023

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Vol. 68, nr 6

307--316

EN

This article is a literature review related to the methods of functionalization of carbon fibers for tissue engineering applications. Through physical modification, it is possible to obtain a layer of a chemical compound on the carbon fibers surface and to impart additional properties. On the other hand, chemical modification may lead to the incorporation of appropriate functional groups into the carbon fiber structure, capable of attaching, among others, biologically active compounds. The paper presents the advantages and disadvantages of the carbon fibers modifying methods, with particular emphasis on the use of such modified fibers in medicine.

PL

Niniejsza praca stanowi przegląd literatury dotyczący metod funkcjonalizacji włókien węglowych przeznaczonych do zastosowań w inżynierii tkankowej. Poprzez modyfikację fizyczną możliwe jest uzyskanie warstwy związku chemicznego na powierzchni włókien węglowych i nadanie im dodatkowych właściwości. Natomiast modyfikacja chemiczna może prowadzić do wbudowania w strukturę włókna węglowego odpowiednich grup funkcyjnych zdolnych do przyłączania m.in. związków aktywnych biologicznie. W pracy przedstawiono zalety i wady stosowanych metod modyfikacji włókien węglowych, ze szczególnym naciskiem na zastosowanie tak modyfikowanych włókien w medycynie.

14

Nośność graniczna próbek wykonanych z betonu samozagęszczalnego układanego wewnątrz rur kompozytowych

Ostrowski Krzysztof Adam, Sikora Oliwia, Furtak Kazimierz

Inżynieria i Budownictwo

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2023

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R. 79, nr 11-12

604--607

PL

W ostatnich latach materiały kompozytowe są szeroko stosowane w celu wzmacniania istniejących konstrukcji, także betonowych. Na ogół proces ten polega na przyklejeniu maty lub taśmy z włókien węglowych (bądź innych) do uprzednio przygotowanej powierzchni betonu, najczęściej przy użyciu żywicy epoksydowej. Wykonywanie konstrukcji betonowych - szczególnie słupów betonowych - wiąże się między innymi z koniecznością wykonania deskowania, systemów rusztowań i późniejszego rozformowania elementu. Proces ten bywa czasochłonny, co wpływa na szybkość wykonania i koszt słupów betonowych. W pracy zaproponowano sposób wykonywania rur kompozytowych z laminatów węglowych oraz ich późniejsze wykorzystanie jako traconą formę do wykonania cylindrycznych próbek zespolonych. Rury kompozytowe o grubości 0,3 i 0,9 mm wypełniono betonem samozagęszczalnym, a następnie poddano badaniom niszczącym w teście jednoosiowego ściskania. Wytrzymałość na ściskanie betonu w osłonie rury o grubości 0,3 mm (SCC-0,3) i 0,9 mm (SCC-0,9) była odpowiednio większa o 37% i 95% w porównaniu z betonem referencyjnym. Średnia wartość maksymalnej odkształcalności osiowej grup próbek wyniosła 0,0048, 0,0069 i 0,0151, odpowiednio dla betonu samozagęszczalnego (SCC), SCC-0,3 i SCC-0,9. Odnotowano także wzrost modułu sprężystości podłużnej betonu wewnątrz rur kompozytowych. Uzyskane wyniki wykazały dobrą współpracę zbrojenia zewnętrznego (rury kompozytowej) z rdzeniem betonowym, pomimo małej przyczepności pomiędzy tymi elementami.

XX

In recent years, composite materials have been widely used to reinforce existing structures, including concrete elements. This process generally consists in gluing a carbon fibers (or other) mat to a previously prepared concrete surface, most often using epoxy resin. Making concrete structures - especially concrete columns - involves the need to make formwork and scaffolding systems and then demolding the elements. This process can be time-consuming, which affects the speed and cost of building a concrete column. This work proposes a method of preparing composite tubes from carbon laminates and their subsequent use as a lost mold for the production of cylindrical composite samples. Composite tubes with an average thickness of 0.3 and 0.9 mm were filled with self-compacting concrete and then subjected to destructive testing in the uniaxial compression test. The compressive strength of the concrete in the 0.3 mm (SCC-0.3) and 0.9 mm (SCC-0.9) pipe sheath was 37% and 95% higher, respectively, compared to the reference concrete. The average value of the maximum axial deformation was 0.0048, 0.0069 and 0.0151 for self-compacting concrete (SCC), SCC-0.3 and SCC-0.9, respectively. An increase in the modulus of elasticity was also noted for the concrete in the composite pipes. The obtained results showed good cooperation of the external reinforcement (composite tube) with the concrete core, despite the infinitesimal adhesion between these elements.

15

Influence of Carbon Fibre Reinforced Polymer and Recycled Carbon Fibres on the compressive behaviour of self-compacting high-performance fibre-reinforced concrete

Ostrowski Krzysztof, Furtak Kazimierz

Archives of Civil Engineering

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2023

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Vol. 69, nr 2

53--64

EN

In recent years, carbon fibres have been extensively used to strengthen concrete structures. In most cases, the lamination process is carried out using epoxy resin as matrix. In some cases, especially when strengthen structural elements made of weak concrete, it is possible to replace the epoxy resin with an inorganic, cement matrix, while at the same time maintaining a sufficient efficiency of strengthen understood as the percentage increase in the compressive strength of concrete samples due to the applied reinforcement in relation to the reference concrete. In these studies, elements of carbon fibres mats that are reinforced with a cement matrix were used as the starting product for fibre recovery. The laminate, which was used to reinforce concrete elements, was detached from the concrete surface and subjected to processing in order to obtain clean carbon fibre scraps without cement matrix. Then, the obtained carbon material, in shaped form, was used to strengthen self-compacting, high performance, fibre reinforced concrete (SCHPFRC). For comparative purposes, this concrete was also strengthened by carbon fibre mats (with one and three layers of CFRP). Each samples were tested in uniaxial compression test. The compressive strength of concrete reinforced with 1 and 3 layers of CFRP was higher by 37.9 and 96.3%, respectively, compared to the reference concrete. On the other hand, the compressive strength of concrete reinforced with 1 and 3 layers of carbon fibre scrapswas higher by 11.8 and 40.1%, respectively. Regardless of the reinforcement technique used, the composite elements showed a higher deformability limit in comparison plain concrete. The obtained results showed that it is possible to reuse carbon fibre to strengthen structural elements made of SCHPFRC effectively, using simple processing methods.

PL

W ostatnich latach włókna węglowe są szeroko stosowane do wzmacniania konstrukcji betonowych. W większości przypadków proces laminowania odbywa się z użyciem żywicy epoksydowej jako matrycy. Czasami, zwłaszcza przy wzmacnianiu elementów konstrukcyjnych wykonanych z betonu o stosunkowo niskiej wytrzymałości na ściskanie, możliwe jest zastąpienie żywicy epoksydowej matrycą nieorganiczną; cementową, przy jednoczesnym zachowaniu dostatecznej efektywności wzmocnienia - rozumianej jako procentowy wzrost wytrzymałości betonu na ściskanie wskutek zastosowania materiału kompozytowego, w odniesieniu do betonu referencyjnego. W procesie kruszenia jako nadawę zastosowano elementy betonowe wzmocnione matami z włókien węglowych przy zastosowaniu matrycy cementowej. Laminat został oderwany od powierzchni betonu i poddany dalszej obróbce w celu uzyskania czystych, niezawierających matrycy cementowej skrawków mat z włókna węglowego. Następnie otrzymany materiał został wykorzystany do wzmocnienia samozagęszczalnego, wysokowytrzymałościowego fibrobetonu (SCHPFRC). Dla celów porównawczych beton ten został także wzmocniony z użyciem mat z włókien węglowych (1 i 3 warstwy wzmocnienia). Próbki cylindryczne przebadano w teście jednoosiowego ściskania. Wytrzymałość na ściskanie betonu wzmocnionego 1 i 3 warstwami CFRP była wyższa odpowiednio o 37,9 i 96,3% w porównaniu z betonem referencyjnym. Natomiast wytrzymałość betonu wzmocnionego 1 i 3 warstwami strzępów z włókna węglowego była wyższa odpowiednio o 11,8 i 40,1%. Niezależnie od zastosowanej techniki wzmocnienia, próbki kompozytowe cechowały się wyższą odkształcalnością graniczną w odniesieniu do betonu referencyjnego. Uzyskane wyniki wykazały, że możliwe jest wykorzystanie włókien węglowych z recyklingu do efektywnego wzmocnienia elementów konstrukcyjnych wykonanych z SCHPFRC, przy użyciu nieskomplikowanej metody przeróbki odpadu.

16

Research on piezoresistive effect and random model of carbon fiber bundle

Gong Yifei, Xie Zhiyu, Liu Jiarong, Chen Guanhao, Zhang Dawei

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e128, 2023

EN

Carbon fibers and corresponding composites are being widely used in strengthening and repairing existing reinforced concrete structures. The piezoresistive effect of carbon fibers can be applied to self-monitor its stress and damage. However, rare piezoresistive models can be found in the literature considering the mesoscopic mechanism and material randomness of carbon fiber bundles to quantify the piezoresistive effect. The piezoresistive effect of carbon fiber bundles is mainly affected by the elastic deformation, breakage, and contact of filaments. In this paper, according to the analysis of these factors, a dynamic random equivalent parallel circuit model was established to quantify the piezoresistive effect of carbon fiber bundles during tension. With tensile results of 54 carbon fiber bundles, the uncertainties of filaments, such as the initial breakage, tensile breakage and contact change, were analyzed and their probability distributions were determined. The strength of filaments is subject to the Weibull distribution. Kolmogorov-Smirnov (K-S) test results show that the initial breakage ratio obeys a truncated lognormal distribution and the relative contact ratio change obeys a truncated normal distribution. Then Monte Carlo simulations were used to calculate the electrical resistance of carbon fiber bundles during tension. Comparing the simulated resistance with that of 15 verifying specimens, this piezoresistive model and calculation method is reliable and valid.

17

Electromagnetic interference shielding effectiveness of multi-cracked strain-hardening cementitious composites (SHCC)

Kim Soonho, Jang Yun Sik, Oh Taegeun, Lee Seung Kyun, Yoo Doo-Yeol

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e179, 2023

EN

With the rapid increase in the use of wireless electronic devices, electromagnetic pollution has been recognized as a serious threat. There has been an increasing demand for the use of cement composites as electromagnetic shielding materials. Thus, this study investigated the advantages of adding a small dosage of carbon fibers to enhance the mechanical and electrical properties of strain-hardening cementitious composites (SHCCs) containing steel fibers. In addition, the effect of microcrack formation on the electromagnetic interference (EMI) shielding effectiveness of the SHCCs was analyzed. For this purpose, four different residual tensile strains were applied in preloading tests in the range of 0.015–0.1%. The test results suggested that the tensile performance of the SHCCs was improved by adding 0.2 vol% carbon fibers. Moreover, the rate of increase of the energy absorption capacity was higher (50%) than those of the tensile strength and strain capacity. The electrical conductivity and EMI shielding effectiveness of the SHCCs were noticeably increased by the addition of carbon fibers. The highest shielding effectiveness of 45.6 dB, at 1 GHz, was achieved for the SHCC containing 2% steel fibers and 0.2% carbon fibers, which was approximately 6% higher than that of the corresponding plain SHCC with only steel fibers. An approximately 44–47% lower shielding effectiveness was observed with the formation of through microcracks; however, the number of cracks and the residual tensile strain did not significantly influence the shielding effectiveness. This study can be a basis for evaluating EMI shielding effectiveness of damaged structures.

18

Flexural response of FRP‑strengthened lightweight RC beams: hybrid bond efficiency of L-shape ribbed bars and NSM technique

Tahmouresi Behzad, Momeninejad Kasra, Mohseni Ehsan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e95, 1--16

EN

This paper presents the results of an experimental study on employing near surface mounted (NSM) fiber-reinforced polymer (FRP) reinforcement technique, and L-shape ribbed bars, for flexural strengthening of lightweight reinforced concrete (RC) beams. 18 RC beams including 14 lightweight RC beams and four normal-weight concrete beams were designed. The beams were strengthened with glass fiber-reinforced polymer (GFRP) bars and carbon fiber-reinforced polymer (CFRP) laminate in bending tests. Test parameters included: (1) different FRP materials (glass bars and carbon sheets), (2) longitudinal steel reinforcement ratio, and (3) type of strengthening technique used (NSM reinforcement or hybrid). The ultimate tensile strength, deflection, compressive and tensile strain of concrete, and failure mode of the beams were examined under four-point flexural test. Results showed that the ultimate strength of all RC beams increased between 33 and 105% compared to the control beam. The ultimate strength of beams reinforced with CFRP in the mid-span region was 10% higher than that of beams strengthened at both ends, although the former exhibited 28% lower ultimate deflection. The ultimate strength and deflection of RC beams strengthened with combined steel reinforcing bars and GFRP bars were 10% and 108% higher, respectively, compared to those of RC beams strengthened with GFRP bars only. Hybrid L-shape ribbed bars beams showed a considerably higher ductility (up to 170% increase in the ultimate deflection) compared to other beams. The comparison of the experimental results of the ultimate strength of the beams with ACI440-2R guidelines indicated a reasonable and conservative prediction of the code expression.

19

Electromagnetic wave absorption performance of UHPC incorporated with carbon black and carbon fiber

Xu Shenchun, Yang Yekai, Wu Chengqing, Liu Kai

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e71, 1--17

EN

This study focuses on the electromagnetic wave absorption performance (EWAP) of ultra-high-performance concrete (UHPC) incorporated with carbon black (CB) and carbon fiber (CF) in 2-18 GHz frequency range (required for the radar wave absorbing materials). The reflectivity of the traditional UHPC was investigated and compared to the cement-based composites reported in the literatures, so as to illustrate the advantages of novel UHPCs with respect to EWAP. Afterwards, the effect of CB and CF on the compressive strength, complex permittivity and reflectivity of the novel UHPCs was investigated. The microstructure of the novel UHPCs was also explored via scanning electron microscopy to illustrate the mechanism of performance enhancement on incorporating CB and CF. The results indicated that EWAP of the traditional UHPC was similar or inferior (at specific frequencies) to the literature reported cement-based composites. However, EWAP of the novel UHPCs was significantly improved after reinforcing with CB or CF. A positive effect of CB and CF was also observed on the compressive strength of the developed UHPCs. This study provides avenues for the use of UHPCs in protecting structures for absorbing the electromagnetic waves and safeguarding these structures against extreme loads, including blast and penetration.

20

Modeling of high-speed flywheel designs for technological equipment

Dehtiarov Ivan, Antosz Katarzyna, Avramenko Serhiy, Herasko Kostyantyn, Ivanov Vitalii

Technologia i Automatyzacja Montażu

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2021

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nr 2

13--19

PL

W artykule przeanalizowano konstrukcję napędów mechanicznych oraz obszary ich zastosowania. Na podstawie przeprowadzonej analizy opracowano projekt napędu kinetycznego opartego na sprzęgle z materiału kompozytowego, przeznaczonego do pracy z wysoką częstotliwością obrotową. Zaproponowano najbardziej optymalne koła zamachowe pod względem akumulacji energii kinetycznej i jednocześnie maksymalnej wytrzymałości konstrukcji oraz przeprowadzono ich symulację numeryczną. Na podstawie wyników analizy modalnej ustalono wartości i postaci częstotliwości własnych oscylacji wirników ze sprzęgłami o różnych konstrukcjach, co pozwala na sterowanie procesem, znając graniczne wartości maksymalnej dopuszczalnej częstotliwości obrotów. Na podstawie modelowania numerycznego ustalono, że kształt sprzęgła oraz jego masa mają istotny wpływ na ograniczenie prędkości obrotowej. Jednocześnie sprzęgło o najmniejszej masie, ale największej częstotliwości obrotów ma maksymalną jednostkową energochłonność, co świadczy o tym, że jest to najbardziej efektywny wariant pod względem kosztów materiałowych i zastosowania tej konstrukcji w urządzeniach do gromadzenia energii podczas pracy urządzeń technologicznych. Porównano koszt dla sprzęgła o zawartości materiału kompozytowego powyżej 68% z kosztem sprzęgła, które ma maksymalną wartość jednostkową energochłonności na 1 kg masy.

EN

The article analyzes the design of mechanical energy drives and their use areas. Based on the analysis, the kinetic energy drive designis based on the composite material's flywheel, capable of working with a high frequency of rotation. The most optimal flywheels in terms of accumulation of kinetic energy and at the same time the maximum strength of the design are proposed, and their numerical simulation is carried out. The modal analysis results established the values and forms of the eigenfrequencies of oscillations of rotors with flywheels of various structures, which allows controlling the process of overclocking, knowing the limit values of the maximum permissible frequency of rotation of the flywheels. Numerical modeling established that the flywheel's shape and its mass significantly affect the rotor speed limit with the flywheel. At the same time, the flywheel with the lowest mass but the highest frequency of rotation has the maximum specific energy intensity per unit of mass, which determines it as the most effective option in terms of the cost of material and the use of this design in devices for energy accumulation during the operation of technological equip-ment. The calculation results also show that the lamb flywheel has the most incredible absolute energy in-tensity. Simultaneously, the costs of the composite material above 68% are compared with the flywheel, which has the maximum specific value of the energy intensity per 1 kg of its mass.