This project is about mechanical characterization of high performance, structural composite materials. Within the context of this project, a commercial, now available epoxy resin reinforced with carbon nanotubes (CNT’s) was compared with a high performance commercially available epoxy resin, also using unidirectional carbon fiber as reinforcement agent. CNT’s are a relatively new, interesting topic to study within the materials science, and because of the potential shown in previous studies, are of utter importance for critical structural applications, such as those found in the aerospace industry. During this project previous references were studied and used as comparison material to design the methodological framework followed in this work. To observe CNT’s benefits, samples tailored to American Society for Testing and Materials (ASTM) standards were manufactured and tested in order to quantify the mechanical properties discussed in this. ASTM standards provide both the sample dimension requirements and the testing procedure to be followed in order to obtain reliable, organized, meaningful data from proposed tests. Tensile, shear and flexural strain-strength tests were performed in samples using both kinds of resins. Data collected from tests was organized, plotted and analyzed to understand mechanical behavior of the samples during the tests. Main engineering values such as ultimate tensile strength, engineering stress, young’s modulus, shear strength and so were gathered and documented in this project. CNT’s reinforced epoxy samples outperformed the common epoxy samples in general, showing a better behavior as seen in the deformation energy absorbed in the samples in each test. It is encouraged to keep the research on the CNT’s topic as a promising and relevant technology called to grow in use and performance in the future, as well as to expand and improve the difficulties and limitations found in this project. This project shows that even when using a low CNT’s content as reinforcement agent within the matrix, evaluated mechanical properties are effectively enhanced, making the CNT’s a good candidate for future composite material components where weight saving and better structural mechanical performance is needed.

Carbon Composites: Composites with Carbon Fibers, Nanofibers, and Nanotubes, Second Edition, provides the reader with information on a wide range of carbon fiber composites, including polymer-matrix, metal-matrix, carbon-matrix, ceramic-matrix and cement-matrix composites. In contrast to other books on composites, this work emphasizes materials rather than mechanics. This emphasis reflects the key role of materials science and engineering in the development of composite materials. The applications focus of the book covers both the developing range of structural applications for carbon fiber composites, including military and civil aircraft, automobiles and construction, and non-structural applications, including electromagnetic shielding, sensing/monitoring, vibration damping, energy storage, energy generation, and deicing. In addition to these new application areas, new material in this updated edition includes coverage of cement-matrix composites, carbon nanofibers, carbon matrix precursors, fiber surface treatment, nanocarbons, and hierarchical composites. An ideal source of information for senior undergraduate students, graduate students, and professionals working with composite materials and carbon fibers, this book can be used both as a reference book and as a textbook. Introduces the entire spectrum of carbon fiber composites, including polymer-matrix, metal-matrix, carbon-matrix, ceramic-matrix and cement-matrix composites Systematically sets out the processing, properties, and applications of each type of material Emphasizes processing as the foundation of understanding, manufacturing, and designing with composite materials

This book covers micro and macro aspects of toughened composites covering polymer matrix, metal matrix, ceramic matrix and nanomatrix. It gives the reader understanding of composite fabrication, construction, and lightweight yet high crack resistance performance, macroscopic testing supported by microscopic bonding and debonding features, models of stress transfer, and commercial features of developing cheaper yet high-quality materials. Features: Focuses on micro and macro aspects of toughening methods and principles of composite materials. Includes all types of composites including polymer matrix, metal matrix, ceramic matrix and nanomatrix. Covers corrosion resistance and oxidation resistance as well as solubility resistance. Discusses the use of recycled materials. Provides a good balance of long fibre, short fibre, nanoparticle and particulate modifiers. This book aims at researchers and professionals in materials science, composite materials, fracture mechanics, materials characterization and testing, properties and mechanics, nanomaterials, aerospace and automotive engineering and structural engineering.

This research is focused on investigating the effect of carbon nanotubes on macroscale composite laminate properties, such as, interlaminar shear strength, interlaminar fracture toughness and electrical conductivity along with studying the micro and nano-scale interactions of carbon nanotubes with epoxy matrix via thermomechanical and electrical characterization of nanocomposites. First an introduction to the typical advanced composite laminates and multifunctional nanocomposites is provided followed by a literature review and a summary of recent status on the processing and the characterization work on nanocomposites and composite laminates. Experimental approach is presented for the development of processing techniques and appropriate characterization methods for carbon nanotubes reinforced epoxy resin based multi-functional nanocomposites and carbon fiber reinforced polymer composite laminates modified with carbon nanotubes. The proposed work section is divided into three sub-sections to describe the processing and the characterization of carbon nanotube reinforced epoxy matrix nanocomposites, woven-carbon fabric epoxy matrix composite laminates modified with selective placement of nanotubes and unidirectional carbon fiber epoxy matrix composite laminates modified with carbon nanotubes. Efforts are focused on comparing the effects of functionalized and unfunctionalized carbon nanotubes on the advanced composite laminates. Covalently functionalized carbon nanotubes are used for improved dispersion and fiber-matrix bonding characteristics and compared with unfunctionalized or pristine carbon nanotubes. The processing of woven carbon fabric reinforced epoxy matrix composite laminates is performed using a vacuum assisted resin transfer molding process with selective placement of carbon nanotubes using a spraying method. The uni-directional carbon fiber epoxy matrix pre-preg composites are processed using a hot press technique along with the spraying method for placement of nanotubes. These macroscale laminates are tested using short beam shear and double cantilever beam experiments for investigating the effect of nanotubes on the interlaminar shear stress and the interlaminar fracture toughness. Fractography is performed using optical microscopy and scanning electron microscopy to investigate the structure-property relationship. The micro and nano-scale interactions of carbon nanotubes and epoxy matrix are studied through the processing of unfunctionalized and functionalized single wall carbon nanotube reinforced epoxy matrix nanocomposites. The multifunctional nature of such nanocomposites is investigated through thermo-mechanical and electrical characterizations.

Carbon nanotubes (CNTs) are ideal candidates for the reinforcement of the matrix and interphase zone in polymer matrix composites (PMCs), due to their ability to more effectively bind the reinforcing fibers to the matrix material. This can lead to the enhancement of several critical composite properties - including interfacial shear strength and interlaminar fracture toughness - that are typically associated with a composite material's resistance to delamination. Direct dispersion of CNTs into the matrix of the composites has been shown to be very difficult. A more effective way to reinforce PMCs using CNTs is to grow CNTs directly on the reinforcing fibers. To this end, a novel technique used to grow CNTs directly on carbon fibers has been developed at The University of Alabama and Auburn University. This method, referred to as the PopTube Approach, uses microwave irradiation to grow CNTs at room temperature in air, without the need for inert gas protection or additional feed stock gases. The simple nature of the PopTube Approach lends itself to large-scale, high-yield manufacturing that can be done in a cost effective manner. However, before this technique is developed beyond the laboratory scale, its effectiveness as a route to produce CNT-reinforced composites must be evaluated in a comprehensive manner. The objective of this work is to do just that - characterize the mechanical properties of CNT-reinforced composites produced via the PopTube Approach. A systematic experimental program is carried out to provide a comprehensive assessment of the effects of the PopTube Approach on a wide range of composite mechanical properties. Results show that the PopTube Approach provides for enhanced resistance to delamination with respect to several different loading events. Fractography studies are used to qualitatively understand the mechanisms responsible for these improvements in delamination resistance on the micro-scale. Results also suggest that improvements in delamination resistance via CNT reinforcement may come at the expense of the tensile properties of PMCs - which gives rise to the conclusion that in practice, the degree and manner of CNT reinforcement in PMCs should be carefully considered on an application-by-application basis. Together, the collection of studies performed herein provides a wide-ranging quantitative and qualitative assessment of the effects of the PopTube Approach CNT reinforcement scheme on the mechanical properties and behavior of polymer matrix composites.

Provides introductory information on carbon fiber composites, including polymer-matrix, metal matrix, carbon-matrix, ceramic-matrix, and hybrid composites. Places emphasis on materials rather than mechanics.

This book brings together a diverse compilation of inter-disciplinary chapters on fundamental aspects of carbon fiber composite materials and multi-functional composite structures: including synthesis, characterization, and evaluation from the nano-structure to structure meters in length. The content and focus of contributions under the umbrella of structural integrity of composite materials embraces topics at the forefront of composite materials science and technology, the disciplines of mechanics, and development of a new predictive design methodology of the safe operation of engineering structures from cradle to grave. Multi-authored papers on multi-scale modelling of problems in material design and predicting the safe performance of engineering structure illustrate the inter-disciplinary nature of the subject. The book examines topics such as Stochastic micro-mechanics theory and application for advanced composite systems Construction of the evaluation process for structural integrity of material and structure Nano- and meso-mechanics modelling of structure evolution during the accumulation of damage Statistical meso-mechanics of composite materials Hierarchical analysis including "age-aware," high-fidelity simulation and virtual mechanical testing of composite structures right up to the point of failure. The volume is ideal for scientists, engineers, and students interested in carbon fiber composite materials, and other composite material systems.

This book covers the innovative methodologies and strategies adopted in carbon materials research area including: Synthesis, characterization, and functionalization of carbon nanotubes and graphene Surface modification of graphene Carbon-based nanostructured materials The use of carbon nanomaterials for energy applications Development of carbon nanotubes reinforced metal matrix composites and non-metallic composites and their myriad potential end-use applications Key challenges to the successful and widespread implementation of carbon nanotubes reinforced metal matrix composites and non-metallic composites Methods for quantification and improved control of carbon nanotubes distributions Recent research and design trends for carbon nanomaterials-based sensors for a variety of applications Advances and potential applications in environmental monitoring and healthcare

Carbon fiber is an oft-referenced material that serves as a means to remove mass from large transport infrastructure. Carbon fiber composites, typically plastics reinforced with the carbon fibers, are key materials in the 21st century and have already had a significant impact on reducing CO2 emissions. Though, as with any composite material, the interface where each component meets, in this case the fiber and plastic, is critical to the overall performance. This text summarizes recent efforts to manipulate and optimize the interfacial interaction between these dissimilar materials to improve overall performance.

Fiber reinforced composite driveshaft are seen as an attractive replacement for metallic driveshaft in helicopters. Rigid matrix composite (RMC) are composites reinforced with a strong fiber such as carbon fibers in a rigid matrix such as an epoxy. Matrix plays an important role in the determining the properties of the fiber composites, for instance mechanical and thermal properties can be tailored by changing molecular structure of the polymer matrix or incorporating nanoparticles in the matrix. The objective of this research is to evaluate, experimentally and analytically, at multiple length scales, the effects of adding spherical nanosilica (NS) particles on the thermomechanical properties of carbon/epoxy composites. Starting from a molecular scale, a novel thermodynamically fundamental mechanism is developed that simulates the cross-linking of epoxide and an aromatic amine (DETDA) curing agent. Good agreement between the simulations and the experimental results were seen for tensile modulus, glass transition temperature, and mass density. The complete simulation procedure, including cross-linking, equilibration and testing of the polymer, was carried out using reactive force fields.Epoxies cured with three different curing agents (3,3-diaminodiphenylsulfone (DDS), 4-4-DDS, and DETDA) were included in all the experiments. Epoxies with variable concentrations of NS were mechanically characterized for modulus, fracture toughness, density, and glass transition temperature. The addition of NS improved the modulus and fracture toughness, although it also decreased the glass transition temperature slightly, possibly due to the diluent component of the master batch of NS-filled bis F. This investigation provides, for the first time, a full set of 2-D lamina properties of T700 carbon fiber composites with 0 wt % NS (0NS) and 37 wt % NS (37NS) cured with DETDA. Equations for predicting the 2D properties as functions of NS and carbon fiber contents were developed using micromechanics principals and backed-out properties of T700 fibers. At the lamina level, NS increased the longitudinal and transverse compression strengths and descreased the transverse coefficient of thermal expansion, which are beneficial for overall composite performance. Using these predictive equations, a simple design exercise was conducted for []5 carbon/epoxy driveshafts with and without NS, considering strength, buckling, torsional stiffness, and whirl. The use of NS improved the safety factors for strength, buckling, and torsional stiffness for all ply angles. However, using NS increased the weight of the shaft and consequently reduced the safety factor for whirl at ply angles less than approximately 60 degrees, which is the realm where NS does not significantly increase the bending stiffness of the shaft due to the dominating effect of the fibers.Tubular specimens with 0, 15, 25 and 34 wt % NS cured with 4,4DDS and 0 and 37 wt % NS cured with DETDA were ballistically impacted at normal incidence and evaluated for damage area and residual torsional strength. This is the first study on NS-filled composites with ballistic impact where the projectile punctures through the composite. Incoporating NS into the composite decreased the projected damage area, increased the residual torsional strength, and increased the energy absorption per unit projected damage area. Specimens manufactured with 15NS/DDS and 25NS/DDS exhibited the highest residual strengths. An analytical model was developed to calculate the damage area and residual projectile velocity after normal-incidence impact. This model is an extension of a previous energy-based model for cross-ply laminates, with original modifications developed for angle plies and dual walls. Good agreement between the experimental and analytical residual velocities was obtained. Analytical and experimental damage areas display a similar trend with NS content, but the analytical damage areas were always less than the experimental areas. Tubular specimens with 0 and 15 wt % NS with DETDA curing agent were obliquely impacted with a ballistic projectile and subjected to residual torsional strength testing. No significant change in damage area or residual torsional strength was seen in these experiments, indicating a negligible effect of NS in an impact scenario where the oblique path of the projectile, rather than the toughness of the composite, is the main factor affecting the size of the damage zone.