High thermal conductivity of carbon nanotubes has motivated us to study and understand the thermal mechanisms in nanocomposites. Though several theoretical models predict a high thermal conductivity for CNT reinforced polymer composites, the experimental validation are not so encouraging. A finite element model of MWNT reinforced nanocomposite is developed based on continuum mechanics approach. The finite element model is a representative volume element (RVE) with single MWNT inclusion. The inclusion is modeled based on the continuum model of MWNT as effective solid fiber [22]. The interface resistance between the nanotube and the matrix material is modeled using thermal contact elements. The finite element analysis was carried out keeping volume fraction of MWNT fibers as constant and varying three important parameters which influences the effective thermal conductivity. Analysis with varying volume fractions of CNT fibers was also carried out to study the influence of volume fraction. The results obtained were in agreeable range with the theoretical calculations made based on the work of Bagchi and Nomura [22]. The effective thermal conductivity of MWNT reinforced nanocomposites with MWNTs of high aspect ratios showed gradual increase in conductivity with increase in length while it showed a drastic decrease in effective thermal conductivity with increase in the diameter of the MWNT inclusion. The finite element analysis showed that the interface resistance between the nanotube and the matrix material does not affect effective thermal conductivity noticeably which is contradictory with few theoretical models which attribute interface resistance for lower than expected effective thermal conductivity. The analysis predicts linear increase of effective thermal conductivity with increase in volume fraction of the MWNT fibers in matrix material; this is also in accordance with the theoretical model. The above analysis also validates the use of finite element approach based on continuum mechanics in studying the overall behavior of the nanocomposites.

Carbon Nanotube-Reinforced Polymers: From Nanoscale to Macroscale addresses the advances in nanotechnology that have led to the development of a new class of composite materials known as CNT-reinforced polymers. The low density and high aspect ratio, together with their exceptional mechanical, electrical and thermal properties, render carbon nanotubes as a good reinforcing agent for composites. In addition, these simulation and modeling techniques play a significant role in characterizing their properties and understanding their mechanical behavior, and are thus discussed and demonstrated in this comprehensive book that presents the state-of-the-art research in the field of modeling, characterization and processing. The book separates the theoretical studies on the mechanical properties of CNTs and their composites into atomistic modeling and continuum mechanics-based approaches, including both analytical and numerical ones, along with multi-scale modeling techniques. Different efforts have been done in this field to address the mechanical behavior of isolated CNTs and their composites by numerous researchers, signaling that this area of study is ongoing. - Explains modeling approaches to carbon nanotubes, together with their application, strengths and limitations - Outlines the properties of different carbon nanotube-based composites, exploring how they are used in the mechanical and structural components - Analyzes the behavior of carbon nanotube-based composites in different conditions

This book presents a new approach to modeling carbon structures such as graphene and carbon nanotubes using finite element methods, and addresses the latest advances in numerical studies for these materials. Based on the available findings, the book develops an effective finite element approach for modeling the structure and the deformation of grapheme-based materials. Further, modeling processing for single-walled and multi-walled carbon nanotubes is demonstrated in detail.

Carbon-Nanotube-Reinforced-Polymer-Composite (CNRPC) materials have generated widespread interest over the last several years in practical engineering applications, such as aeronautical and aerospace engineering structures. However, studies still need to be carried out to characterize their mechanical properties, especially the dynamic properties, and the effects of defects on the mechanical properties. Experimental investigations intended for this purpose have limitations and, in most cases, reliable cost-effective experimental work could not be carried out. Computational modelling and simulation encompassing multiscale material behavior provide an alternate approach in this regard to characterize the material behavior. A probabilistic approach serves as a suitable approach to characterize the effects of material and structural defects. The present thesis reports the development of a computational framework of the Representative Volume Element (RVE) of a CNRPC material model to determine its static and dynamic responses, and also for the evaluation of its static and dynamic reliabilities based on a probabilistic characterization approach. A 3D multiscale finite element model of the RVE of the nanocomposite material consisting of a polymer matrix, a Single-Walled-Carbon-Nanotube (SWCN) and an interface region has been constructed for this purpose. The multiscale modeling is performed in terms of using different theories and corresponding strain energies to model the individual parts of the RVE of the CNRPC material. The macroscale continuum mechanics is used for the polymer matrix, the mesoscale mechanics is used for the interface region, and the nanoscale-level atomistic mechanics is used for the SWCN. The polymer matrix is modeled using the Mooney-Rivlin strain energy function to calculate its non-linear response, while the interface region is modeled via the van der Waals links. The SWCN is first modeled as a space frame structure by using the Morse potential, and then as a thin shell based on a suitable shell theory. For this purpose, the suitability and the accuracy of popular shell theories for use in the multiscale model of the RVE are assessed.

This volume presents the characterization methods involved with carbon nanotubes and carbon nanotube-based composites, with a more detailed look at computational mechanics approaches, namely the finite element method. Special emphasis is placed on studies that consider the extent to which imperfections in the structure of the nanomaterials affect their mechanical properties. These defects may include random distribution of fibers in the composite structure, as well as atom vacancies, perturbation and doping in the structure of individual carbon nanotubes.

Carbon Nanotube Reinforced Composites introduces a wide audience of engineers, scientists and product designers to this important and rapidly expanding class of high performance composites. Dr Loos provides readers with the scientific fundamentals of carbon nanotubes (CNTs), CNT composites and nanotechnology in a way which will enable them to understand the performance, capability and potential of the materials under discussion. He also investigates how CNT reinforcement can be used to enhance the mechanical, electrical and thermal properties of polymer composites. Production methods, processing technologies and applications are fully examined, with reference to relevant patents. Finally, health and safety issues related to the use of CNTs are investigated. Dr. Loos compares the theoretical expectations of using CNTs to the results obtained in labs, and explains the reasons for the discrepancy between theoretical and experimental results. This approach makes the book an essential reference and practical guide for engineers and product developers working with reinforced polymers – as well as researchers and students in polymer science, materials and nanotechnology. A wealth of applications information is included, taken from the wide range of industry sectors utilizing CNT reinforced composites, such as energy, coatings, defense, electronics, medical devices, and high performance sports equipment. - Introduces a wide range of readers involved in plastics engineering, product design and manufacturing to the relevant topics in nano-science, nanotechnology, nanotubes and composites. - Assesses effects of CNTs as reinforcing agents, both in a materials context and an applications setting. - Focuses on applications aspects – performance, cost, health and safety, etc – for a wide range of industry sectors, e.g. energy, coatings, defense, electronics, medical devices, high performance sports equipment, etc.

While the relevant features and properties of nanosystems necessarily depend on nanoscopic details, their performance resides in the macroscopic world. To rationally develop and accurately predict performance of these systems we must tackle problems where multiple length and time scales are coupled. Rather than forcing a single modeling approach to

Presents technologies and key concepts to produce suitable smart materials and intelligent structures for sensing, information and communication technology, biomedical applications (drug delivery, hyperthermia therapy), self-healing, flexible memories and construction technologies. Novel developments of environmental friendly, cost-effective and scalable production processes are discussed by experts in the field.

Modeling of single-walled carbon nanotubes, multi-walled nanotubes and nanotube reinforced polymer composites using both the Finite Element method and the Molecular Dynamic simulation technique is presented. Nanotubes subjected to mechanical loading have been analyzed. Elastic moduli and thermal coefficient of expansion are calculated and their variation with diameter and length is investigated. In particular, the nanotubes are modeled using 3D elastic beam finite elements with six degrees of freedom at each node. The difficulty in modeling multi walled nanotubes is the van der Waal's forces between adjacent layers which are geometrically non linear in nature. These forces are modeled using truss elements. The nanotube-polymer interface in a nano-composite is modeled on a similar basis. While performing the molecular dynamic simulations, the geometric optimization is performed initially to obtain the minimized configuration and then the desired temperature is attained by rescaling the velocities of carbon atoms in the nanotube. Results show that the Young's modulus increases with tube diameter in molecular mechanics whereas decreases in molecular dynamics since the inter-atomic potential due to chemical reactions between the atoms is taken into consideration in molecular dynamics unlike in molecular mechanics.

Fiber composite materials are ideal engineered materials to carry loads and stresses in the fiber direction due to their high in-plane specific mechanical properties. However, premature failure due to low transverse mechanical properties constitutes a fundamental weakness of composites. A solution to this problem is being addressed through the creation of a nano-reinforced laminated composite (NRLC) materials where carbon nanotubes (CNTs) are grown on the surface of the fiber filaments to improve the matrix-dominated properties. The carbon nanotubes increase the effective diameter of the fiber and provide a much larger interface area for the polymeric matrix to wet the fiber. The objective of this thesis work is to numerically predict the elastic properties of these nano-reinforced fiber composites. Finite Element Method (FEM) is used to evaluate the effective mechanical properties employing a 2D and 3D cylindrical representative volume element (RVE) based on multiscale modeling approach. In continuum mechanics, perfect bonding is assumed between the carbon fiber and the polymer matrix and between the carbon nanotubes and the polymer matrix. In the multiscale modeling approach in this work, cohesive zone approach is employed to model the interface between carbon fiber and polymer matrix and between the CNTs and the polymer matrix. Traction-displacement plots obtained from molecular dynamics simulations are used to derive the constitutive properties of the cohesive zone material model used for CNT-Polymer interface. For NRLC, the cohesive zone material model properties are assumed based on the information found in the literature. Effective material constants are extracted from the solutions of the RVE for different loading cases using theory of elasticity of isotropic and transversely isotropic materials. Experimental mechanical characterization data is used for correlation and validation of numerical results. It is observed that the cohesive zone material model is capable of capturing the interface behavioral details and provides more realistic results for the mechanical response of composite materials. Experimental results show that the potential improvement in matrix-dominated properties of the NRLC suggested by the numerical study can be realized only with the availability of improved and sophisticated NRLC fabrication techniques.