Thesis (M.S.) in Civil Engineering--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 117-122).

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Corrosion presents one of the greatest threats to the durability of reinforced concrete structures, yet it is also one of the least understood components of the design process for most engineers. The nation's infrastructure is rapidly deteriorating due to years of abuse and fatigue. Therefore, several economic and reliable solutions have been developed to repair the existing damage and extend the design life of structures at risk of corrosion. One popular method for protecting concrete structures from corrosion is the use of fiber-reinforced plastic (FRP) composite wraps. The premise is a simple one: placing an impermeable barrier around the surface of the concrete should prevent harmful substances such as chlorides from entering and corroding the imbedded reinforcing steel. However, little is known about the long-term effectiveness in preventing corrosion in reinforced concrete structures. The FRP wrap may in fact prevent the chlorides from passing through the concrete, however, the same principle might cause chlorides to be trapped beneath the surface and accelerate corrosion. In this study, the long-term behavior of laboratory specimens exposed to an aggressive chloride-rich environment were examined. This project was designed to develop a greater understanding of the long-term effects of FRP wrapping in preventing corrosion in reinforced concrete structures. Although TxDOT project 0_1774 involves both rectangular and cylindrical specimens, the focus of this thesis is on the specific impact of FRP wraps on partially wrapped versus unwrapped columns. The specimens included in this study are comprised of a wide range of construction parameters. However, despite the multitude of varying mix designs a noticeable trend has emerged as a result of this research. / text

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The student inclusive Green Raven project of the KTH-Aero faculty requireda small blended wing model of their new flying wing design. The small scalemodel will be used for various flight tests. The goal of this specific project was tocreate an internal structure for the small scale model, including an outer shell.Two-dimensional drawings were created and tested in a simulation software.The model was then drawn in cad. Lastly the wing was strength tested inAnsys mechanical. The beams in the structure are made of Scots pine due toits accessibility and good strength to weight ratio. The outer shell is made outof fiberglass. A quick connection between the wing and the main body wasimplemented for easy transportation. All final testing indicate that the finaldesign had sufficient strength regarding the initial load requirements.

During a risk assessment undertaken in a factory dealing with fiber reinforced plastic products in the northwestern part of Peninsular Malaysia, styrene was identified as the most potential hazard in the factory. It was therefore chosen to focus the rest of the risk assessment on this chemical. The purpose of this risk assessment was to find out which negative health effects styrene could have on the factory workers, especially on the laminators who are dealing daily with styrene at a close range during lamination through hand lay-up. This was investigated theoretically through a literature research and practically through measurements of styrene in the air in the factory. The styrene doses were measured on two occasions at several distances away from the potential sources. These measurements were high compared with dose-response relationships found in the literature and various national occupational exposure limit values with regards to styrene. The calculated risk quotient (RQ) was also greater than one and it is therefore likely that styrene has negative health effects on the workers in the factory. The various negative health effects identified in the literature were then included in a risk matrix were they were ranked according to the probability that they would have a negative effect on the factory workers. Hearing- and colourvision effects were ranked as very likely, effects on the central nervous system and the respiratory system as well as livertoxicity were classified as likely and genotoxicity was ranked as a possible negative health effect. In the future it would be interesting to talk to the current laminators and do health check-ups to see if they are suffering from any of the suggested negative health effects. It would also be interesting to follow them on a longterm basis to see if their health is changing and if this can be linked to the styrene handling in the factory. / Vid en riskbedömning i en fabrik i nordvästra Malaysia identifierades styren som den största hälsofaran för fabriksarbetarna, framförallt laminerarna eftersom de ofta hanterar styren på nära håll. Det valdes därför att fokusera den resterande riskbedömningen just på styren och dess möjliga negativa hälsoeffekter. Syftet med studien var att ta reda på om styren kan ha en negativ effekt på fabriksarbetarnas hälsa. Detta undersöktes teoretiskt genom en litteraturstudie och praktiskt genom mätningar av styrenhalten i fabriken. Vid två tillfällen mättes styrenhalten i fabriken. De uppmätta halterna jämfördes sedan med de dos-responssamband som funnits vid litteraturstudien, samt med olika nationella hygieniska gränsvärden för styren. De uppmätta värdena visade sig vara höga jämfört med de funna i litteraturen. Det bidrog tillsammans med den beräknade riskkvoten som visade sig vara större än ett, till slutsatsen att styren har en negativ effekt på fabriksarbetarnas hälsa. De möjliga negativa hälsoeffekter som identifierats i litteraturen rangordnas med hjälp av en riskmatris enligt sannolikheten att de skulle utgjöra en risk för arbetarna i fabriken. Effekter på hörseln och färgseendet ansågs vara mycket sannolikt, effekter på centrala nervsystemet (CNS) och levern samt irritation av andningssystemet ansågs sannolika och att styren skulle vara genotoxiskt ansågs möjligt. Övriga hälsoeffekter ansågs osannolika eller mycket osannolika. I framtida studier skulle det vara intressant att diskutera med de nuvarande laminerarna och undersöka dem medicinskt för att se om de har påverkats utav några av de förväntade hälsoeffekterna. Det vore också intressant att följa dessa arbetare under en längre tid för att se om deras hälsa ändras på något sätt som skulle kunna kopplas till styrenhanteringen i fabriken.

Masonry structures constitute a significant portion of building stock worldwide. Seismic performance of unreinforced masonry has been far from satisfactory. Masonry is purported to be a major source of hazard during earthquakes by reconnaissance surveys conducted aftermath of an earthquake. Reasons for the poor performance of masonry structures are more than one namely lack of deformational capacity, poor tensile strength & lack of earthquake resistance features coupled with poor quality control and large variation in strength of materials employed. Fibre Reinforced Plastic (FRP) composites have emerged as an efficient strengthening technique for reinforced concrete structures over the past two decades. Present thesis is focused towards analysing the behaviour of Fibre Reinforced Plastic (FRP) strengthened masonry under axial compression and in-plane shear loading. Determination of in-planes hear resistance of large masonry panels requires tremendous effort in terms of cost, labour and time. Masonry assemblages like prisms and triplets that represent the state of stress present in masonry walls and masonry in-fills when under the action of in-planes hear forces present an alternative option for research and analysis purposes. Hence, present research is focused towards analysing the performance of FRP strengthened masonry assemblages and unreinforced masonry assemblages. Chapter1 provides a brief review on the behaviour of masonry shear walls and masonry in-fills under the action of in-plane shear forces in addition to the performance of masonry structures during past earthquakes. Review of available literature on FRP confinement of masonry prisms with bed joints inclined from 00 to 900 to the loading axis under axial compression, analytical models available for FRP confined concrete, shear strength of masonry triplets attached with FRP is presented. Chapter 2 primarily focuses on determining the various properties of the materials involved in this research investigation. Test procedure and results of the tests conducted to determine the mechanical and related properties of the materials involved are presented. Elastic properties and stress-strain response of burnt clay brick, mortar and FRP laminates are presented. Studies conducted on behaviour of GFRP confined masonry prisms under monotonic axial compression are included in Chapter 3. The study comprised of testing masonry prisms, both unconfined and FRP confined masonry prisms under axial compression. Stretcher bond and English bond prisms, with bed joints normal and parallel to loading axis are included in this study. Two grades of GFRP,360g/m2 and 600 g/m2 are employed to confine masonry prisms. The experimental program involved masonry prism types that accounted for variations in masonry bonding pattern, bed joint inclination to the loading axis and grade of GFRP. Review of the available analytical models predicting compressive strength of FRP confined masonry prism is presented. Available models for FRP confinement of masonry are re-calibrated using the present experimental data generating new coefficients for the already existing model to develop new expression for predicting the compressive strength of FRP confined prisms. In addition to the prism types mentioned earlier, behaviour of unconfined and GFRP confined stretcher bond prisms with bed joints inclined at 300, 450 & 600 to the loading axis are further investigated. Chapter 4 primarily deals with the shear strength and deformational capacity of masonry triplets that represent joint shear failure in masonry. An experimental program involving masonry triplets attached with different types of FRP(GFRP and CFRP), grade of FRP, percentage area covered by FRP and reinforcement pattern is executed. This exercise determined the influence of these parameters over the enhancement achieved in terms of shear strength and ultimate displacement. Results of tests conducted on stretcher bond prisms presented in chapter 3 and results of tests on shear triplets presented in this chapter are combined to study the interaction between shear and normal stresses acting along the masonry bed joint at different angles of inclination. The thesis culminated with chapter 5 as concluding remarks highlighting the salient Information pertaining to the behaviour of FRP strengthened masonry under axial compression and in-plane shear loading obtained as an outcome of the research conducted as a part of this thesis.

In der vorliegenden Arbeit wird die Steifigkeits- und Festigkeitsauslegung von mittels der Tailored Fiber Placement (TFP)-Technologie hergestellten Faser-Kunststoff-Verbunden (FKV) am Beispiel eines einteiligen Rotors aus kohlenstofffaserverstärktem Epoxidharz (CFK) für den Einsatz in Turbomolekularpumpen (TMP) vorgestellt. Im Vergleich zu anderen textilen Fertigungsverfahren können mit Hilfe der TFP-Technologie Verstärkungsfaserrovings in der Ebene variabelaxial, d. h. mit ortsunabhängiger, frei wählbarer Richtung, definiert abgelegt werden. Die sticktechnische Fixierung der Rovings mit Hilfe eines Nähfadens führt zu Welligkeiten und Materialinhomogenitäten in TFP-basierten Faser-Kunststoff-Verbunden (FKV). Dadurch werden die Materialeigenschaften beeinflusst. Mit Hilfe einer Prozessanalyse in Kombination mit morphologischen Untersuchungen werden in dieser Arbeit die welligkeitsinduzierenden Effekte in TFP-basierten FKV identifiziert und quantifiziert. Darauf aufbauend wird ein mesoskaliges Repräsentatives Volumenelement (RVE) einer TFP-Einheitszelle auf Basis von Finiten Elementen entwickelt. Mit Hilfe des RVE wird es erstmalig ermöglicht, die Dehnungs- und Spannungsverteilung sowie den lokalen Faservolumengehalt in TFP-basierten FKV zu berechnen und daraus wirklichkeitsnahe Materialkennwerte abzuleiten. Darüber hinaus wird anhand des RVE der Einfluss variierender TFP-Prozessparameter auf die resultierenden Steifigkeits- und Festigkeitseigenschaften analysiert. Weiterhin wird der Einfluss des unter Langzeitbelastung eintretenden Matrixkriechens auf die Materialeigenschaften von TFP-basierten FKV untersucht. Anhand der Entwicklungsschritte eines CFK-TMP-Rotordemonstrators werden die Besonderheiten beim Auslegungsprozess für Bauteile aus TFP-Strukturen verdeutlicht. Neben der Erläuterung der Lastfälle von TMP-Rotoren wird die Entwicklung eines lastfallangepassten Faserlayouts unter Berücksichtigung von geometrischen Restriktionen beschrieben. Im Rahmen der Spannungsanalyse auf Basis der Finite Elemente Methode (FEM) erfolgt die Integration der mittels des RVE bestimmten Materialdaten in das FE-Modell schichtweise, entsprechend der verwendeten TFP-Prozessparameter. Die mit dieser Vorgehensweise berechnete Versagensdrehzahl und die ermittelten Eigenfrequenzen konnten in experimentellen Untersuchungen erfolgreich validiert werden. Durch die Integration der ortsaufgelösten RVE-basierten Materialdaten wird erstmalig nicht nur die Struktursteifigkeit, sondern auch die Festigkeit ausgehend von einem variabelaxialen TFP-Ablagemuster in einem TFP-basierten Bauteil vorhergesagt. Mit dem entwickelten TMP-Rotordemonstrator kann die Versagensdrehzahl gegenüber dem Stand der Technik um 45 % gesteigert werden. In der Arbeit wird auch herausgestellt, welche Änderungen der Geometrie von TMP-Rotoren aus FKV nötig sind, um eine werkstoffgerechte, an die orthotropen Eigenschaften von FKV angepasste Gestaltung zu realisieren und damit die Nenndrehzahlen weiter steigern zu können. Diese Erkenntnisse dienen in verallgemeinerter Weise der werkstoffgerechten Auslegung und Fertigung von TFP-basierten FKV-Bauteilen. / The present work demonstrates the stiffness and strength design of fiber reinforced plastics (FRP) made by the Tailored Fiber Placement (TFP) technology using the example of a a turbo molecular pump (TMP) rotor made of carbon fiber reinforced epoxy resin (CFRP). In contrast to other textile preform manufacturing processes, the TFP technology enables the placement of reinforcement rovings in arbitrary direction according to an user defined design path. In this technology a double locked stitch in a zigzag stitch pattern is used to fixate the rovings. The fixation process leads to waviness and material inhomogeneities within the placed rovings resulting in reduced material properties in TFP-based fiber reinforced plastics. The wavinessinducing effects have been identified and quantified by detailed process analysis and morphological investigations. Subsequently, a meso-scaled representative volume element (RVE) of a TFP unit cell based on finite elements was developed. The RVE provides the opportunity to derive realistic material properties by calculating the stress and strain distribution as well as as the local fiber content in TFP-based FRP. In this work, the influence of different TFP process parameters on the resulting modulus and strength has been investigated using the RVE approach. Additionally, long term loading effects leading to a reduced matrix modulus were analyzed numerically with the RVE. Based on the development of the CFRP TMP rotor specific characteristics of the design process for components made of TFP are clarified. Besides the explanation of loading conditions of TMP rotors the progress of a load-adapted fiber layout considering geometrical restrictions is demonstrated. For the stress analysis based on the Finite Element Method (FEM) material data calculated with the RVE according to the applied TFP process parameters have been integrated into the FE model. The numerically determined failure speed and the calculated eigenfrequencies were successfully validated by experimental tests. By implementing TFP specific material data in the FE model, both, the strucural rigidity as well as the strength, were predicted for the first time in a TFP-based component. Compared to the state-of-the-art, the developed TMP rotor offers an increased failure speed by 45 %. Furthermore necessary geometric modifications for FRP based TMP rotors in order to achieve a material-specific design adapted to the orthotropic material properties and thus to further increase the nominal rotational speeds were shown. These findings provide in a generalized way for a material-specific design of TFP-based FRP components.

Kolfiberkompositer är ett av de materialsom utvecklas snabbast just nu. Analogt med att materialet blir billigare och börjar användas i större utsträckning av flygindustrin utvecklas också tillverkningsmetoder för att följa framstegen. Hur material och tillverkningsmetoder sätter krav och påverkar en produkts utformning och prestanda kan vara svårt att definiera. I detta examensarbete har en Design for Manufacturing och Assembly (DFM/A)-metod utvecklats för att under hela produktutvecklingsprocessen kunna ta hänsyn till produktionsaspekter. DFM/Ametoden är framtagen åt Saab Aerostructures med hänsyn till de material som används, deras existerande produktionsprocesser och den produktutvecklingsprocess som finns på företaget. Utifrån litteratur- och fallstudier har en DFM/A-metod som kallas Metod 2015 (M2015) utvecklats. Metoden innehåller en arbetsprocess, konstruktionsriktlinjer samt stödjande DFM/Averktyg. Genom att i hela utvecklingsprocessen ta hänsyn till produktionsaspekter är detta arbetssätt anpassat för att underlätta utveckling av kolfiberkompositkomponenter på Saab. Utöver själva metoden i sig finns allt material som behövs för användning av M2015 sammanställt i en manual som i första hand riktar sig till konstruktören. Genom att skapa en bättre förståelse för produktionsaspekterna hos en konstruktion och tillhandahålla rätt verktyg kan DFM/A-metoden bidra till flera positiva effekter. Användandet av M2015 bör leda till produkter av kolfiberkomposit som är lättare att tillverka vilket i sin tur också bör minska onödiga kostnader, ge högre kvalitet och kortare ledtider. Införandet ställer dock också krav på Saab för att dessa målsättningar ska kunna uppnås. / Carbon fiber reinforced plastic (CFRP) is one of the fastest developing materials right now. Analogously to the material becoming cheaper and being used more widely in the aerospace industry the manufacturing methods have developed to follow the progress. How material and manufacturing method change the requirements and affect a product's design and performance can be hard to determine. This degree project has developed a Design for Manufacturing and Assembly (DFM/A) method to easier take into consideration the production process throughout the product development. The DFM/A method is developed for Saab Aerostructures and is based on their materials, production process and product development process. By studying literature and performing case studies a DFM/A method called Method 2015 (M2015) was developed. The method includes a work procedure, design guidelines and supporting DFM/A tools. By considering the production aspects throughout the development process this method of operation facilitate the development of CFRP products at Saab. In addition to the method itself the materials needed to use M2015 is compiled in a manual for the designer. By creating a better understanding of the production aspects of a design and providing the right tools the DFM/A method can contribute to several positive effects. The use of M2015 should lead to CFRP products that are easier to produce which in turn should minimize unnecessary costs, raise the quality and shorten lead times. However, the implementation of M2015 at Saab also creates demands to reach these targets

Electromagnetic interference (EMI) is one of the most common problems encountered in microwave applications. Interaction of electromagnetic (EM) waves from different sources may result in device malfunction due to misinterpretation of the transferred data or information loss. On the other hand, development of materials with reduced radar detectability is desired in defense applications. Considering the limitations in weight and thickness, development of lightweight structural materials with enhanced electromagnetic absorption potential is needed. In this study, development and characterization of glass fiber-reinforced polymer (GFRP) composite materials to be used in EM wave absorbing or EMI shielding applications was aimed. Incorporation of electromagnetic wave absorption characteristic has been achieved by the application of conductive thin film on fiber glass woven fabric reinforcement layers. Characterization of EM wave absorption potential was conducted using &ldquo / free-space method&rdquo / in 18 &ndash / 27 GHz frequency range. Single and multilayered combinations of surface-modified fiber glass woven fabrics were characterized in terms of their EM wave interaction properties and design principles for efficient broadband EM wave absorbing multilayered GFRP composite material have been presented. A computer aided computation method has also developed in order to predict EM wave transmission, reflection, and hence absorption characteristics of multilayered structures from single layer properties. Estimated results were verified compared to free-space measurement results. In the current study, up to 85% electromagnetic wave absorption has been obtained within 18-27 GHz frequency range (K band). Enhancement of EM wave absorption potential of multilayer structure has also been demonstrated by computer aided computation.