La consommation globale de plastique renforcé de fibres de carbone (PRFC) est en constante augmentation, ce qui induit la nécessité de créer un secteur de recyclage capable de traiter l’ensemble des fibres de carbone actuellement consommées et qui représente la quantité de déchets à traiter en devenir. Cette thèse porte sur le développement et l'application d’une méthodologie d’évaluation multicritère du développement durable pour la création d’une filière de recyclage des plastiques renforcés de fibres de carbone (PRFC) issus du secteur aéronautique, mais aussi des autres secteurs consommateurs de fibres de carbone tels que l’automobile et l’éolien. Cette méthodologie a pour but d’identifier les indicateurs les plus pertinents ainsi que les méthodes qui leurs sont associés, c'est-à-dire qu’elle vise à la création et l’adaptation d’indicateurs clé de performance du développement durable pour caractériser au mieux les impacts environnementaux et sociaux-économique de cette filière de recyclage. Le résultat final de ce travail est la création d’une méthodologie d’évaluation du développement durable dédiée à la filière de recyclage des fibres de carbone par la considération des différents aspects de celui-ci. Cette méthodologie, aidant à l’identification et la définition des indicateurs clé de performances du développement durable peut être aussi appliquée à d’autres secteurs souhaitant s’implanter en suivant les principes de ce développement. / The global consumption of carbon-fiber reinforced plastic (CFRP) is constantly growing since the last decade, leading to the need to create a recycling sector able to manage the amount of carbon fibers currently consumed and representing the amount of waste to be treated in the future. This thesis focus on the creation of a methodology for evaluating the sustainability potential for the implementation of a carbon fiber reinforced plastics recycling (CFRP) sector. CFRP coming from the aeronautics sector as well as other sectors such as the automobile and wind-energy industries. This methodology aims at identifying the most relevant indicators and associated methods, but also aims at the creation and adaptation of indicators to best assess the environmental and socioeconomic impacts of this recycling sector. The final result of this work, is the creation of a sustainability assessment methodology dedicated to the carbon fiber recycling sector, considering the different sustainability pillars. However this methodology also define more widely a tool that helps to identify sustainability performance indicators and that can be applied to other sectors if necessary.

Fibre Reinforced Polymer Composites are extensively used in aircraft structures because of its high specific stiffness, high specific strength and tailorability. Though Fibre Reinforced Polymers offer many advantages, they are not free from problems. The damage of different nature, e.g., service mechanical damages, fatigue damage or environmental damage can be observed during operating conditions. Among all the damages, manufacturing or service induced, delamination related damage is the most important failure mechanisms of aircraft-composite structures and can be detrimental for safety. Delamination growth under fatigue loading may take place due to local buckling, growth from free edges and notches such as holes, growth from ply-drops and impact damaged composites containing considerable delamination. Delamination growth can also occur due to interlaminar stresses, which can arise in complex structures due to unanticipated loading. The complex nature of composite failure, involving different failure modes and their interactions, makes it necessary to characterize/identify the relevant parameters for fatigue damage resistance, accumulation and life prediction. An effort has been made in this thesis to understand the fatigue behavior of carbon fibre reinforced epoxy laminates under aircraft wing service loading conditions. The study was made on laminates with different lay-up sequences (quasi-isotropic and fibre dominated) and different geometries (plain specimen, specimen with a hole and ply-drop specimen). The fatigue behaviour of the composite was analyzed by following methods: . Ultrasonic C-Scan was used to characterize the delamination growth. . Dynamic Mechanical Analysis (DMA) was done to study the interfacial degradation due to fatigue loading. In this analysis, the interfacial strength indicator and interfacial damping were calculated. The DMA also provides the storage modulus degradation under fatigue loading. . Scanning electron microscope examination was carried out to understand the fatigue damage mechanisms. . A semi-empirical phenomenological model was also used to estimate the residual fatigue life. This research work reveals that the Carbon Fibre Reinforced Polymer laminates are in the safe limit under service loading conditions, except the specimen with a hole. The specimen with a hole showed delaminations around the hole due to stress concentration and higher interlaminar stresses at the hole edges and this delamination is found to be associated with fibre breakage and fibre pullout. The quasi-isotropic laminate is found to show poorer fatigue behaviour when compared to fibre dominated laminate and ply-drop also shows poor performance due to high stress concentration in the ply-drop region.

Předložená disertační práce se zabývá zesílením kruhových železobetonových sloupů pomocí vlákny vyztužených polymerů (tzv. FRP – fibre reinforced polymer) namáhaných laterálním cyklickým zatížením. Tato výzkumná studie se zaměřuje na zkoumání využití FRP tkaniny pro dodatečné zesílení, zlepšení chování kruhových železobetonových sloupů a vytvoření návrhového algoritmu pro zesílení kruhového sloupu pomocí kompozitních FRP materiálů. Návrhový algoritmus byl odvozen na základě analytické studie, numerických simulací a výsledků experimentální činnosti. Na základě těchto výsledků byl navržen postup pro návrh zesílení sloupů ovinutím, který předpovídá chování železobetonových sloupů vystavených laterálním cyklickým zatížením. Při experimentální práci byly zkušební vzorky zatíženy současně axiální sílou a příčným cyklickým zatížením. Toto bylo provedeno dvěma různými způsoby. První způsob zatěžování byl proveden konstantní velikostí laterální síly po daný počet cyklů (1 milion) se sledováním změny deformace. A druhý způsob provedení spočíval v zatížení konstantní deformací se sledováním úbytku síly během zatěžovací zkoušky. Dizertační práce rovněž předkládá přehled současného stavu poznání zesílení železobetonových kruhových sloupů ovinutím FRP tkaninou vystavených působení seismického zatížení. Dále uvádí přehled návrhových metodik a normová ustanovení Eurokódu a ACI. Experimentální program byl proveden za účelem ověření chování ovinutých kruhových sloupů při působení laterálního cyklického zatížení. Závěr práce sumarizuje poznatky o chování sloupů zesílených ovinutím FRP tkaninou při působení laterálního cyklického zatížení a představuje empirický model pro návrh zesílení ovinutím při vysokém a nízkém cyklickém zatížení.

Die Arbeit beschreibt die skalenübergreifende Modellierung und Simulation des Werkstoffverhaltens von Faser-Kunststoff-Verbunden mit textiler Verstärkungsstruktur, die ausgehend von den konstitutiven Eigenschaften der Verbundbestandteile (Mikroskala) und ihrer geometrischen Anordnung im Verbund (Mesoskala) die rechnerische Vorhersage des effektiven Materialverhaltens des Verbundes (Makroskala) ermöglicht. Neben Schädigungsprozessen beeinflusst insbesondere das dehnratenabhängige Materialverhalten der polymeren Matrix das mechanische Verhalten des Verbundes. Dieser Einfluss wird anhand verschiedener Glasfaser-Polypropylen-Verbunde numerisch untersucht. Ein viskoplastisches Materialmodell bildet dabei das nichtlineare Materialverhalten von Polypropylen ab. Die Modellierung der textilen Verstärkungsstruktur erfolgt durch Anwendung der erweiterten Finiten-Elemente-Methode (XFEM). Anhand des Vergleichs von rechnerisch und experimentell gewonnenen Ergebnissen erfolgt schließlich die Verifikation der vorgeschlagenen Modellierungsstrategie. / This contribution covers the trans-scale modelling and simulation of the mechanical behaviour of textile-reinforced polymers. Starting from the material properties of the individual constituents (micro-scale) and their geometrical arrangement (meso-scale), the effective material behaviour of the composite (macro-scale) is numerically predicted. In addition to damage processes, the inelastic deformation behaviour of the composite is influenced by the strain-rate dependent material behaviour of the polymeric matrix. This influence is numerically investigated for different glass-fibre-polypropylene composites. A viscoplastic material model accounts for the nonlinear mechanical behaviour of polypropylene. The complex textile reinforcement is modelled by the eXtended finite element method (XFEM). A comparison of computed and experimental results allows for the verification of the proposed modelling strategy.

When implementing a bridge design proposal, it is common that several alternatives be considered, each with a different material of construction. Traditional building materials used for the construction of bridges have mainly been concrete, steel, timber or aluminium. With all these materials options, maintenance and replacement costs throughout the lifespan of a bridge make up for a large proportion of their total life cycle costs. Fiber Reinforced Polymer (FRP) provides a new viable construction material, which can be implemented in bridge construction. This plastic based material has favourable material properties such a very high strength to weight ratio, high corrosion resistance and durability, as well as very low maintenance costs over its lifetime. In the feasibility analysis, a case study of an existing FRP deck bridge was taken and examined in three aspects: structural, economic and environmental. The bridge was also redesigned with a concrete deck solution, to provide a comparison to a conventional construction material. The results were found, in general to be favourable towards the FRP solution. From the structural analysis savings on deflection, support reactions and superstructure stresses were outputted. Economically, the composite material was found to have a substantial higher initial cost but much lower periodic maintenance costs than the concrete option. Finally the FRP bridge option displayed a lower construction time for the superstructure, at one third of that of concrete and an overall lower environmental impact, based on material production and the overall bridge construction process.

i Abstract The Nockeby Bridge, in the western part of Stockholm, is a prestressed concrete bridge with an openable swing span of steel. The bridge was built during 1970 and should now be widened with 0.5 meters on each side. The concrete bridge deck is supported by two main-beams and cross-beams are located at the position of all supports. Previous studies of the bridge show that the torsional resistance is too low and the bridge needs strengthening while widened. The aim of this master  thesis  was  to  study  and  compare  different  strengthening  methods  for  The  Nockeby Bridge.  Eight  different  bridges  in  Sweden  and  China  were  reviewed  to  find  possible  strengthening  methods  for  The  Nockeby  Bridge.  External  prestressing  tendons  and  additional  cross-beams between  the  two  main-beams  were  seen  to  have  good  influence  on  the  resistance.  The  effect from strengthening with carbon-fiber reinforced polymer was questioned during small loads and was not seen as a suitable strengthening method for The Nockeby Bridge.  Four different FE-models were generated to be able to compare two strengthening methods. The compared strengthening methods were a method with additional cross-beams between the main-beams and a method with external prestressing tendons. All FE-models were built up by solid- and  truss  elements  where  the  concrete  was  modelled  with  solid  elements  and  the  prestressed reinforcement was modelled with truss elements.  Only a few load-cases were included to limit the scope of the study. The included load-cases were deadweight,  prestressing  forces  and  vehicle  load  from  standard  vehicle  F,  G,  H  and  I.  Two influence lines were created to be able to place the vehicle loads in an unfavorable way. From the FE-models, shear  stresses were  extracted  along two  lines, one  on  each  side  of the main-beam. The torsional part of the shear stresses was calculated from these two results and compared with the torsional resistance of the bridge. While calculating the torsional resistance, the normal force in the cross-section from prestress was extracted with the function “free body cut”. The results showed that none of the tested strengthening methods were enough to  strengthen The  Nockeby  Bridge.  However, the  method  with additional  cross-beams  was  seen  as  a  better method than external prestressing tendons. A combination of the two methods might be suitable but  was  not  tested.  Adding  four  cross-beams  in  each  span  might  also  increase  the  resistance enough, but this was neither tested. It was also seen that a reduction of the torsional stiffness had a large influence on the result. Such a reduction is allowed in some cases and should be utilized if possible. Furthermore,  it  was  seen  that  solid-models  were  extremely  time  consuming  and  there  is  not  a  good alternative to design a bridge with only a solid model. / Nockebybron i västra Stockholm är en förspänd betongbro med ett öppningsbart svängspann av stål. Bron byggdes 1970 och ska nu breddas med 0.5 meter på varje sida. Betongplattan stöds upp av två huvudbalkar och tvärbalkar är placerade vid samtliga stöd. Tidigare studier av bron visar att brons vridstyvhet är låg och bron behöver förstärkas i samband med breddningen. Syftet med detta examensarbete är att undersöka och jämföra olika förstärkningsmetoder för Nockebybron. Åtta olika  broar  i  Sverige  och  Kina  undersöktes  för  att  hitta möjliga  förstärkningsåtgärder  för Nockebybron. Extern spännarmering och extra tvärbalkar mellan de två huvudbalkarna hade en bra inverkan på kapaciteten. Kapacitetsökningen fån förstärkning med kolfiberförstärkt plast är ifrågasatt vid låga laster och uppfattas inte som en bra metod för att förstärka Nockebybron.  Fyra     olika     FE-modeller     skapades     för     att     jämföra     två     förstärkningsmetoder. Förstärkningsmetoderna som jämfördes var metoden med extra tvärbalkar mellan huvudbalkarna samt   en   metod   extern   spännarmering.   Alla   FE-modeller   byggdes  upp   med  solid-  och stångelement  där  betongen  modellerades  med  solidelement  och  den  förspända  armeringen modellerades med stångelement.  Enbart ett fåtal lastfall inkluderades i studien för att minska studiens omfattning. De inkluderade lastfallen  var  egenvikt,  förspänningskrafter  samt  trafiklast  från  typfordon  F,  G,  H  och  I.  Två influenslinjer  skapades  för  att  placera  trafiklasten  på  ett  ogynnsamt  sätt.  Från  FE-modellerna extraherades   skjuvspänningar   från   bägge   sidor   av   en   av   huduvbalkarna.   Från   dessa skjuvspänningar   beräknades   vrid-delen   av   skjuvspänningarna   som   jämfördes   med   brons vridkapacitet.  När  vridkapaciteten  beräknades  togs  tryckkraften  från  tvärsnittet  fram  genom funktionen ”free body cut”.  Resultatet visade att ingen av de testade förstärkningsmetoderna var tillräckliga för att  förstärka Nockebybron.  Hur  som  helst,  metoden  med  extra  tvärbalkar  ansågs  som  en  bättre  metod  än extern  spännarmering.  En  kombination  av  de  bägge  förstärkningsmetoderna  kan  vara  lämplig men detta testades inte. Att lägga in fyra tvärbalkar i varje spann kan också leda till en tillräcklig ökning av kapaciteten, men detta fall testades inte heller. En reduktion av vridstyvheten sågs ha en stor påverkan på resultatet. En sådan reduktion är tillåten i vissa fall och borde utnyttjas om möjligt. Vidare  upptäcktes  att  en  solidmodell  är  väldigt  tidskrävande  varför  det  inte  är  lämpligt  att  dimensionera en bro enbart med hjälp av en solidmodell.

<div> <p>Due to harsh environmental conditions, the deterioration of prestressed concrete bridge girders is a commonly observed phenomenon in Indiana and much of the Midwest. Concordantly, one widely observed damage scenario is deteriorated end regions of prestressed concrete girders. Damaged or failed expansion joints expose prestressed concrete girder end regions to chloride-laden water, resulting in a corrosive environment in which reinforcement section loss and concrete spalling can occur. For bridges experiencing this type of deterioration, action is needed to ensure the structure remains safe and serviceable. As such, an experimental program was developed to investigate the effectiveness of three repair techniques in restoring the structural behavior of prestressed concrete bridge girders with end region deterioration. The three examined repair techniques are (i) an externally bonded fiber reinforced polymer (FRP) system, (ii) a near-surface-mounted (NSM) FRP system, and (iii) a concrete supplemental diaphragm. Additionally, installation procedures for the three end region repair techniques were developed. Results, conclusions, and recommendations from the experimental program are presented to help advise best practices for implementing end region repair techniques in the field. </p> </div> <br>

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis provides an approach to incorporate natural composites like Flax Fiber using a resin with 30% bio-content to enhance the packaging boxes made of corrugated cardboard. The objective of introducing natural composite skins is to reduce/eliminate the compressive loading subjected to the boxes while stacking in warehouses.

No description available.

[pt] Materiais compósitos pultrudados poliméricos reforçados com fibra de vidro (PRFV) são aplicados em diversos setores da indústria por apresentarem boas resistências mecânicas, baixo peso específico e alta resistência à corrosão. A exposição a ambientes agressivos tais como imersão em água, condicionamento sob alta umidade relativa, temperatura baixa e elevada, ciclos térmicos e úmidos, bem como a combinação desses efeitos, tornou-se cada vez mais objeto de estudo para esses tipos de materiais. A compreensão dos efeitos das condições ambientais no comportamento do material é essencial para avaliar seu desempenho e, desta forma, garantir a segurança necessária ao projeto estrutural. Com o objetivo de compreender melhor a influência de diferentes condições ambientais nas propriedades do material compósito PRFV, foram estudados os efeitos da temperatura e umidade, além da ação combinada dessas duas condições, nas suas propriedades físicas, químicas, térmicas e mecânicas. Neste estudo, foram levados em conta aspectos importantes que influenciam o comportamento do material, como a resina utilizada, o grau de cura, e características químicas e físicas do material. Os ensaios experimentais foram conduzidos em quatro condições ambientais: (i) exposição a temperaturas moderadas/elevadas (70 graus C à 330 graus C), (ii) imersão em água deionizada (25 graus C, 55 graus C e 70 graus C), (iii) exposição à névoa salina em câmaras de envelhecimento higrotérmico (35 graus C, 55 graus C e 70 graus C), e (iv) exposição a ambiente externo real. Além disso, foram aplicados modelos teóricos para avaliação dos resultados. Foi observado que a temperatura, o tempo de condicionamento e a umidade são fatores preponderantes no comportamento do material. Adicionalmente, uma questão importante para o estudo de pultrudados reside na compreensão das propriedades interlaminares do material. Nesse contexto, a fratura interlaminar, associada às fissuras no plano longitudinal entre as camadas do material, é uma das principais causas de falha em compósitos pultrudados. Consequentemente, a análise da fratura em modo II, que avalia o mecanismo da propagação da fissura no plano interlaminar, vem ganhando espaço no estudo de materiais compósitos. A análise de fratura em modo II não é trivial ou normatizada para compósitos pultrudados PRFV, de forma que poucos dados e conclusões efetivas foram obtidos até o momento a esse respeito. Com o objetivo de suprir essa lacuna, realizou-se uma extensa investigação experimental, culminando na proposição de uma nova metodologia para avaliação da fratura em modo II em materiais compósitos poliméricos pultrudados reforçados com fibra de vidro (PRFV). / [en] Pultruded glass-fiber reinforced polymer (GFRP) composites are applied in various industrial sectors due to their good mechanical strength, low specific weight, and high resistance to corrosion. Exposure to aggressive environments has become an increasingly studied topic for these materials, such as immersion in water, conditioning under high relative humidity, low and high temperatures, thermal and humid cycles, as well as the combination of these effects. Understanding the effects of environment condition on material behavior is essential to evaluate its performance and ensure the necessary safety for structural design. In order to better understand the influence of environmental conditions on the properties of GFRPs, the effects of temperature and humidity, as well as the combined action of these two effects, on their physical, chemical, thermal, and mechanical properties were studied. Important aspects that influence the material s behavior were considered, such as the resin used, the degree of curing, and the chemical and physical characteristics of the material. Experimental tests were conducted under four environmental conditions: (i) exposure to moderate/high temperatures (70 degrees C to 330 degrees C), (ii) immersion in deionized water (25 degrees C, 55 degrees C, and 70 degrees C), (iii) exposure to salt spray in hygrothermal aging chambers (35 degrees C, 55 degrees C, and 70 degrees C), and (iv) exposure to real outdoor environment. In addition, theoretical models were applied to evaluate the results. It was observed that temperature, conditioning time, and moisture are predominant factors in material behavior. Additionally, a important issue for the study of pultruded composites lies in understanding the interlaminar properties of the material. In this context, interlaminar fracture, associated with longitudinal cracks between the layers of the material, is one of the main causes of failure in pultruded composites. Consequently, mode II fracture analysis, which evaluates the mechanism of crack propagation in the interlaminar plane, has been gaining ground in the study of composite materials. Mode II fracture analysis is not trivial or standardized for pultruded GFRP composites, so few data and effective conclusions have been obtained in this regard so far. In order to fill this gap, an extensive experimental investigation was carried out, culminating in the proposal of a new methodology for evaluating mode II fracture in pultruded GFRPs.