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FRP:s användning inom brokonstruktioner / FRP's use in bridge structuresAbdi Yussuf, Yusuf, Jalal Ibrahim, Zand January 2019 (has links)
I dagsläget är de flesta broar i Sverige tillverkade med betong eller stål. Dessa broar är många gånger förknippade med stora kostnader som ofta beror på underhåll och reparation. FRP, som står för Fiber Reinforced Polymer, är ett relativt nytt material i bärande stommar men är ett väl etablerat material i förstärkningssammanhang. I Europa och i synnerhet Nederländerna finns det flertal broar byggda i FRP. Men på grund av brist på normer och regelverk att luta sig emot sker det sällan någon form av brokonstruktion med FRP i Sverige. Detta examensarbete syftar till att undersöka befintliga normer och studera hur materialet FRP används vid förstärkning och konstruktion av broar. Vidare syftar även arbetet till att undersöka egenskaperna hos FRP som byggmaterial och jämföra det med konventionella material som stål och betong. FRP, också benämnd fiberkomposit, är ett kompositmaterial som kan sammanställas på flera olika sätt. Genom olika material som kombineras och olika tillverkningsprocesser som används kan man på så sätt ge individuell utformning till materialet för dess användning. Fördelarna med FRP är många, men i allmänhet har det god styrka, god beständighet samtidigt som det har en låg vikt. Detta resulterar i att inom brokonstruktion så ger det strukturen en minskad egenvikt, vilket i sin tur underlättar en mängd olika saker. Detta arbete visar på att FRP-material har fördelaktiga egenskaper och kan i vissa situationer vara mer gynnsamt att använda än stål eller betong. Dock som tidigare påpekat saknas det specifika Eurokoder för detta material. Däremot är vi säkra på att introduktionen av en ny Eurokod samt med uppmuntran från myndigheter kommer användningen av FRP inom brokonstruktion utan tvekan öka. / At present, most bridges in Sweden are made with concrete or steel. These bridges are often associated with high costs, which often depend on maintenance and repair. FRP, which stands for Fiber Reinforced Polymer, is a relatively new material in load-bearing structures but is a well- established material in the context of reinforcement. In Europe and in particular the Netherlands, there are several bridges built in FRP. But due to a lack of norms and regulations to lean against, there is rarely any kind of FRP bridge construction in Sweden. The aim of this thesis is to examine existing norms and study how the material FRP is used in the reinforcement and construction of bridges. Furthermore, this thesis also aims to investigate the properties of FRP as building material and compare it with conventional materials such as steel and concrete. FRP, also called fiber-composite, is a composite material that can be assembled in several different ways. Through various materials that are combined and different manufacturing processes used, one can thus provide individual designs for the material. The benefits of FRP are many, but generally it has good strength, good durability while having a low weight. This results in that within bridge construction, it gives the structure a reduced self-weight, which in turn facilitates a variety of things. This thesis shows that FRP materials have advantageous properties and in some situations can be more favorable to use than steel or concrete. However, as previously pointed out, there are no specific Eurocodes for this material. However we are sure that the introduction of a new Eurocode and encouragement from authorities will undoubtedly increase the use of FRP in bridge construction.
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[en] FATIGUE BEHAVIOR OF CEMENTITIOUS COMPOSITES REINFORCED BY BAMBOO PULP / [pt] COMPORTAMENTO EM FADIGA DE COMPÓSITOS CIMENTÍCIOS REFORÇADOS POR POLPA DE BAMBUEDUARDO DE FIGUEIREDO CAMPELLO 27 June 2007 (has links)
[pt] A utilização de materiais de construção civil a base de
cimento reforçado
com fibras vem aumentando rapidamente nos últimos anos. No
Brasil um vasto
programa experimental para avaliar o comportamento
mecânico desses materiais
através de ensaios de flexão monotônicos e de compressão,
vem sendo
desenvolvidos na PUC/RIO desde 1979. Este trabalho procura
dar continuidade a
essa linha de pesquisa, sendo o primeiro a estudar o
comportamento em fadiga de
compósitos cimentícios reforçados com polpa de bambu,
através de curvas de
vida-fadiga S-N e da cinética de crescimento de trincas.
As curvas S-N foram
levantadas para compósitos entalhados e não entalhados,
contendo 6% em massa
de polpa em relação a massa de cimento. Essas curvas foram
modeladas, com base
nas propriedades mecânicas básicas levantadas nos ensaios
de compressão e
flexão. Com o objetivo de verificar a aplicabilidade da
lei de Paris à cinética de
crescimento de trincas de fadiga nesses compósitos, foi
levantada a relação entre o
comprimento da trinca a e o número de ciclos N durante a
propagação estável da
mesma, adotando-se teores de reforço de 6 e 14% em relação
a massa de cimento.
Finalmente as superfícies de fratura foram avaliadas por
meio de microscópio
eletrônico de varredura. / [en] The use of fiber reinforced cementious composites as
construction materials
in civil engineering has rapidly grown in the last few
years. In Brasil, a large
experimental program for evaluating the mechanical
behavior of these materials
has been developed in PUC-RIO since 1979. The present
study has the purpose of
evaluating the fatigue behavior of cementitious composites
by means of
determining the S-N curves for notched and unnotched
specimens. The fatigue
curves were modeled using basic mechanical properties
determined by means of
compression and slow bend tests. With the purpose of
verifying the applicability
of Paris law to the fatigue crack growth kinetics, the
crack length was determined
as a function of the number of cycles N during stable
crack propagation, for
composites containing 6% and 14% weight percentage of
bamboo pulp relative to
the weight of cement. Finally, the fracture surface was
analyzed by means of
scanning electron microscopy.
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Analysis and Connection of Lightweight CFRP Sandwich Panels for Use as Floor Diaphragms in Structural Steel BuildingsKaiser, Richard Lawrence January 2014 (has links)
A lightweight carbon fiber reinforced polymer (CFRP) sandwich panel has been developed for floor use in commercial office building construction. CFRP laminate skins were combined with low-density rigid polyurethane foam to create a composite sandwich panel suitable for floor use. The CFRP sandwich panel was optimized to withstand code prescribed office-building live loads using a 3D finite element computer program called SolidWorks. The thickness of the polyurethane foam was optimized to meet both strength and serviceability requirements for gravity loading. Deflection ultimately was the controlling factor in the design, as the stresses in the composite materials remained relatively low. The CFRP sandwich panel was then subjected to combined gravity and lateral loading, which included seismic loads from a fictitious 5-story office building located in a region of high seismic risk. The results showed that CFRP sandwich panels are a viable option for use with floors, possessing sufficient strength and stiffness for meeting code prescribed design loads, while providing significant benefits over traditional construction materials.
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Thermal Behaviour Of Mono-Fibre Composites And Hybrid Composites At Cryogenic TemperaturesPraveen, R S 04 1900 (has links) (PDF)
Hybrid composites forms an important field of research in the area of composite science and engineering as it gives the advantage of avoiding complex lay-up designs and provides better tuning compatibility to get desired properties in comparison with their mono-fiber counterpart.
Further, utilization of composites for low temperature structures has been hindered by inconsistency of material property data and not much is reported on thermal characteristics of hybrid composites at cryogenic temperatures.
This research work is focused on development of carbon-glass epoxy hybrid composite and to study the thermal behavior of these materials in comparison to its mono-fiber counterparts especially at cryogenic temperatures. The objectives are classified into the following three parts:
Development of a hybrid composite with urethane modified epoxy matrix system (toughening agent used is Propyltrimethoxysilane (PTMO) and Toluene Di-Isocyanate (TDI) is added to get the polyurethane structure), for cryogenic applications.
Study and understand the limitations and complexities of the experimental methodologies involved in evaluating the thermal properties of these materials namely thermal conductivity, coefficient of thermal expansion and specific heat.
Finally to look into the appropriate theoretical calculations and experimental results to understand the variations, if any, for these materials.
Specifically the following contributions are reported in this thesis:
Evaluated the modified matrix system for its physical and mechanical properties at 20K. Specimens were prepared with D638 ASTM standard, modified to suit pin loading configuration in the cryostat/Instron machine.
After assessing the suitability of the matrix system, mono fibre composites of different types were made and evaluated their thermal properties viz, coefficient of thermal expansion, thermal conductivity and specific heat down to 20K.
Based on the results of the above, a hybrid composite configuration was evolved which exhibits optimal thermal characteristics at low temperatures and its characterization for various thermal properties at cryogenic temperatures was carried out.
Comparisons of the experimental results were made with macro-mechanical model and micro-mechanical model (rule of mixtures) of composite materials.
The present work throws light to the fact that hybrid polymer matrix composites can very well be considered for cryogenic applications where the combination or trade off between properties like strength to conductivity ratio, modulus to conductivity ratio and low cost is to be made. The mechanical properties of hybrid composites also need to be studied to complement the study on thermal properties reported in this thesis. It is essential to have a complete understanding of behaviour of these materials at cryogenic temperatures with respect to both thermal and mechanical properties as it is evident from the available literature that the emerging demands are multi-disciplinary in nature.
The present research work is aimed at highlighting the use of hybrid composites to achieve the desirable thermal properties and thereby inviting the attention of scientists and engineers who are engaged in the design of cost effective structures and appliances for cryogenic environments to focus on further research to develop
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Investigating damage in discontinuous fiber composites through coupled in-situ X-ray tomography experiments and simulationsImad A Hanhan (8780756) 29 April 2020 (has links)
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<p>Composite materials have become widely used in engineering applications, in order to reduce the overall weight of structures while retaining their required strength.
Due to their light weight, relatively high stiffness properties, and formability into
complex shapes, discontinuous fiber composites are advantageous for producing small
and medium size components. However, qualifying their mechanical properties can
be expensive, and therefore there is a need to improve predictive capabilities to help
reduce the overall cost of large scale testing. To address this challenge, a composite
material consisting of discontinuous glass fibers in a polypropylene matrix is studied
at the microstructural level through coupled experiments and simulations, in order
to uncover the mechanisms that cause microvoids to initiate and progress, as well
as certain fiber breakage events to occur, during macroscopic tension. Specifically,
this work coupled in-situ X-ray micro computed tomography (μ-CT) experiments
with a finite element simulation of the exact microstructure to enable a 3D study
that tracked damage initiation and propagation, and computed the local stresses and
strains in the microstructure. In order to have a comprehensive 3D understanding
of the evolution of the microstructure, high fidelity characterization procedures were
developed and applied to the μ-CT images in order to understand the exact morphology of the microstructure. To aid in this process, ModLayer - an interactive
image processing tool - was created as a MATLAB executable, and the 3D microstructural feature detection techniques were compared to traditional destructive
optical microscopy techniques. For damage initiation, this work showed how high
hydrostatic stresses in the matrix can be used as a metric to explain and predict the exact locations of microvoid nucleation within the composite’s microstructure. From
a damage propagation standpoint, matrix cracking - a mechanism that has been
notably difficult to predict because of its apparent stochastic nature - was studied
during damage propagation. The analysis revealed the role of shear stress in fiber
mediated flat matrix cracking, and the role of hydrostatic stress in fiber-avoidance
conoidal matrix cracking. Overall, a sub-fiber simulation and an in-situ experimental
analysis provided the microstructural physical phenomena that govern certain damage initiation and progression mechanisms, further enabling the strength and failure
predictions of short fiber thermoplastic composites.
</p></div></div></div>
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[en] EXPERIMENTAL STUDY ON DUCTILITY OF REINFORCED CONCRETE BEAMS STRENGTHENED IN FLEXURE WITH CARBON FIBER COMPOSITES / [pt] ESTUDO EXPERIMENTAL DA DUCTILIDADE DE VIGAS EM CONCRETO ARMADO REFORÇADAS À FLEXÃO UTILIZANDO COMPÓSITOS COM TECIDO DE FIBRAS DE CARBONOMARCELIA GOMES MACHADO 12 January 2005 (has links)
[pt] Este trabalho experimental tem como objetivo estudar a
ductilidade de vigas retangulares de concreto armado
reforçadas à flexão utilizando compósitos com tecido de
fibras de carbono. No estudo realizado são apresentados os
conceitos clássicos de ductilidade e é proposta uma nova
sistemática para obtenção do índice de ductilidade, baseada
nas considerações da energia elástica e da energia
inelástica. A ductilidade é determinada por meio de um
índice energético, que se caracteriza como uma forma mais
eficiente para a determinação e análise da ductilidade em
elementos estruturais. O programa experimental consistiu no
ensaio de sete vigas bi-apoiadas, sendo uma viga de
referência e as demais reforçadas à flexão com tecido de
fibras de carbono. Todas as vigas possuem as mesmas
características mecânicas e geométricas e foram
dimensionadas de modo a garantir a ruptura por flexão. A
viga de referência, a primeira ensaiada, não foi reforçada
e serviu para comparações de incremento de rigidez e
resistência após a aplicação do reforço. As vigas
reforçadas foram divididas em dois grupos. O grupo A é
constituído de duas vigas, reforçadas inicialmente com uma
e duas camadas de tecido de fibra de carbono. O grupo B é
constituído por quatro vigas que foram reforçadas após
um carregamento inicial. Neste grupo, duas vigas foram
reforçadas com uma camada de tecido de fibra de carbono e
as outras duas foram reforçadas com duas camadas de tecido
de fibras de carbono, correspondendo à mesma área total
de reforço das anteriores. Todas as vigas foram
concretadas, instrumentadas e ensaiadas no Laboratório de
Estruturas e Materiais da PUC-Rio. Os ensaios das vigas do
grupo B foram realizados com as vigas pré-ensaiadas,
reforçadas sob deformação constante e em seguida levadas à
ruptura. A deformação foi mantida constante durante a
aplicação e o período de cura do reforço. Os resultados
obtidos em termos de carga, flecha, momento, curvatura,
ductilidade energética e rotação plástica foram analisados.
Os estudos realizados mostraram que o reforço com
compósitos de fibras de carbono é uma técnica eficaz, que
as vigas apresentam ductilidade adequada e que os índices
energéticos propostos são adequados para este tipo de
estudo. / [en] The objective of this experimental work is to study the
ductility of reinforced concrete beams strengthened in
flexure using externally bonded carbon fiber fabric
composites. This study presents the classic concepts of
ductility and proposes a new systematic to obtain the
ductility index, which is based on the considerations of
elastic and inelastic energy. The ductility was determined
by an energetic index, which has seen to be a more
efficient method to establish and analyze the ductility of
structural elements. The experimental program consisted of
seven beams tests. One was used as a control beam without
external reinforcement and the others were strengthened
with carbon fibers in order to resist flexural load. All
the beams had the same mechanical and geometrical
characteristics and were designed to fail in flexure. The
control beam was not strengthened and its purpose was to
compare the stiffness increase and resistance after the
strength. The strengthened beams were divided in two
groups. Group A was constituted by two beams, initially
strengthened by one and two layers of carbon fiber fabric.
Group B was formed by four beams which were strengthened
after the application of an initial load. In this group,
two beams were strengthened by one layer of carbon fiber
fabric and the other two were strengthened by two layers,
which corresponded to the same area of the others. All the
beams were cast, instrumented and tested in the Structural
and Materials Laboratory at PUC-Rio. Group B tests were
performed with the pretested beams strengthened under
constant strain, and then loaded up to rupture. The strain
was kept constant during the application and cure of the
external reinforcement. The results obtained in terms of
load, deflection, resistant moment, curvature, energetic
ductility indexes and plastic rotation were analyzed. The
study showed that the reinforcement using carbon fiber
fabric composites is an efficient technique, the beams
presented adequate ductility and the proposed energetic
ductility indexes are consistent formulae for this kind of
study.
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[pt] ESTUDO EXPERIMENTAL DO REFORÇO À TORÇÃO DE VIGAS DE CONCRETO ARMADO COM COMPÓSITOS DE FIBRAS DE CARBONO / [en] EXPERIMENTAL STUDY OF TORSIONAL STRENGTHENING OF CONCRETE BEAMS WITH CARBON FIBERS COMPOSITES13 December 2021 (has links)
[pt] Este trabalho de natureza experimental tem como objetivo estudar o comportamento de vigas de concreto submetidas à torção e reforçadas externamente com compósitos de fibras de carbono (CFC). Treze vigas de concreto com 2,0 m de comprimento e seção transversal de 30 cm х 60 cm foram testadas no Laboratório de Estruturas e Materiais do Departamento de Engenharia Civil (LEM/DEC) da Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio). As vigas foram divididas em quatro séries, sendo uma de referência, composta por quatro vigas sem reforço externo, e outras três séries constituídas por três vigas que foram reforçadas externamente com taxas crescentes de estribos de CFC. Com o propósito de estudar a contribuição do concreto e do reforço de CFC na resistência à torção de vigas, a armadura interna só foi colocada na região de aplicação de cargas e nos apoios para evitar a ruptura local e possibilitar o estudo da região central sem a parcela resistente devida à armadura interna de aço. Os resultados dos ensaios mostraram que as vigas reforçadas apresentaram aumento de carga de fissuração entre 16 por cento e 56 por cento e um acréscimo de resistência à ruptura entre 19 por cento e 47 por cento quando comparadas às vigas de referência. A rigidez das vigas na ruptura aumentou proporcionalmente ao crescimento da taxa de reforço como observado em outros ensaios encontrados na literatura. / [en] This research is an experimental study of torsion strengthening of concrete beams with carbon fibers composites. Thirteen concrete beams with 2.0 long and 30 x 60 cm cross section were tested in the Structures and Materials Laboratory of the Civil Engineering Department (LEM/DEC) of Pontifical Catholic University of Rio de Janeiro (PUC-Rio). The beams were divided in four series, the first one was called the reference series and consisted of four beams without external strengthening and each of the other three series was composed of three beams strengthened with increasing rates of external carbon fibers composites stirrups. In oder to allow the study of the central region without the contribution of the steel reinforcement, the internal steel reinforcement was placed only at points of loads application and supports to prevent the local rupture. The tests results showed that the strengthened beams had an increase of the cracking load between 16 per cent and 56 per cent, and an increase of the rupture load between 19 per cent and 47 per cent when compared to the reference beams. The ultimate resistance of the beams increased proportionally to the rate of external carbon fibers composites strengthening, as was observed by other researchers.
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Carbon Nanotube-Based Composite Fibers for Supercapacitor ApplicationAdusei, Paa Kwasi 01 October 2019 (has links)
No description available.
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[pt] ANÁLISE EXPERIMENTAL DA ADERÊNCIA ENTRE O CONCRETO E COMPÓSITOS COM TECIDO DE FIBRAS DE CARBONO / [en] EXPERIMENTAL ANALISYS ON BOND BETWEEN CONCRETE AND CARBON FIBER COMPOSITES FABRICJULIANA MARTINELLI MENEGHEL 02 January 2006 (has links)
[pt] É descrito neste trabalho um programa experimental sobre a
aderência entre os
compósitos com tecido de fibras de carbono e o concreto.
Este programa
experimental consistiu em ensaios de tração-compressão de
corpos-de-prova
compostos de dois blocos de concreto (móvel e fixo)
colados por tiras de tecido
de fibra de carbono coladas nos lados opostos desses
blocos. Foram ensaiados
nove corpos-de-prova, com três resistências à compressão
aos 28 dias de 20,5
MPa, 28,7 MPa e 38,1 MPa e duas larguras do tecido iguais
a 50 mm e 100 mm.
Todos os corpos-de-prova foram concretados, instrumentados
e ensaiados no
Laboratório de Estruturas e Materiais da PUC-Rio. O
objetivo deste trabalho foi
estudar a influência da resistência do concreto e da
largura do tecido de fibra de
carbono sobre a resistência de aderência do sistema. Os
resultados mostraram
que a resistência de aderência pode ser considerada
independente da resistência
do concreto e da largura do tecido. Foi obtido, neste
estudo, um valor
característico de 1,45 MPa para a resistência de aderência. / [en] An experimental study on the bond between carbon fiber
fabric composites and
concrete is described in this work. This experimental
program consisted of
tension-compression tests of specimens with two concrete
blocks (movable and
fixed) jointed by carbon fiber fabric strips bonded on two
opposite sides of these
blocks. Nine specimens, with three concrete compressive
strength of 20,5MPa ,
28,7MPa and 38,1MPa at 28 days and two fabric width of 50
mm and 100
mm, were tested. All specimens had the same geometrical
characteristics. All the
specimens were cast, instrumented and tested in the
Structural and Materials
Laboratory at PUC-Rio. The objective of this work was to
study the influence of
concrete strength and the width of the fabric on the bond
strength of the system.
The results showed that the ultimate bond strength may be
considered
independent of concrete strength and of the width of the
fabric. A characteristic
value of 1.45 MPa was found for the bond strength.
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Fracture Toughness of Carbon Fiber Composite MaterialRea, Allison 14 December 2022 (has links)
No description available.
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