Download or read book Multi scale Modeling of Liquid Crystalline Polymers written by Robert Kehalani Sentinella and published by ProQuest. This book was released on 2008 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid Crystalline Polymers have a wide variety of applications. They are not only interesting to the industrial world, but to the academic world as well. To take full advantage of these interesting materials, it is necessary to develop numerical algorithms that predict their behavior when subjected to processing flows. In the current work, an algorithm was developed that directly solves the full Doi-Marrucci-Greco (DMG) model for a 2D flow domain when subjected to simple shear flow. This algorithm is referred to as the direct solver. Due to the extremely high computational cost of implementing this direct solver, a Multi-Resolution based methodology was designed and proves to be a viable technique in reducing this cost. It also displays promise as a tool that could be applied to different complex fluids problems and perhaps beyond.

Download or read book Multiscale Modeling and Computation of Liquid Crystal Polymers Polymer Blends and Polymer Nanocomposites Investigation of Rheology and Material Properties written by and published by . This book was released on 2008 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-performance polymeric materials such as liquid crystal polymers and polymer nano-particle composites have many military applications. The project aimed to study the mesoscopic structure formation during flow processing and characterization of material properties in solid states. Significant progress has been made to model the materials and to understand their rheological properties in melt or solution processing. Electrical and thermal conduction properties of the nanocomposites are characterized by the low volume fraction asymptotic approach. More anisotropic molecular configuration and their impact to the macroscopic material properties have been investigated. Applications of the models and numerical tools developed for complex fluids are used to important biological applications.

Download or read book Multi scale Phenomena In Complex Fluids Modeling Analysis And Numerical Simulations written by Chun Liu and published by World Scientific. This book was released on 2009-06-12 with total page 379 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-Scale Phenomena in Complex Fluids is a collection of lecture notes delivered during the first two series of mini-courses from “Shanghai Summer School on Analysis and Numerics in Modern Sciences”, which was held in 2004 and 2006 at Fudan University, Shanghai, China.This review volume of 5 chapters, covering various fields in complex fluids, places emphasis on multi-scale modeling, analyses and simulations. It will be of special interest to researchers and graduate students who want to work in the field of complex fluids.

Download or read book Multiscale Modelling of Polymer Properties written by E. Perpète and published by Elsevier. This book was released on 2006-11-18 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modelling in polymer materials science has experienced a dramatic growth in the last two decades. Advances in modeling methodologies together with rapid growth in computational power have made it possible to address increasingly complex questions both of a fundamental and of a more applied nature.Multiscale Modelling of Polymer Properties assembles research done on modeling of polymeric materials from a hierarchical point of view, in which several methods are combined in a multilevel approach to complex polymeric materials. Contributions from academic and industrial experts are organized in two parts: the first one addresses the methodological aspects while the second one focuses on specific applications. The book aims at comprehensively assessing the current state of the field, including the strengths and shortcomings of available modelling techniques, and at identifying future needs and trends. * Several levels of approximation to the field of polymer modelling; ranging from first-principles to purely macroscopic * Contributions from both academic and industrial experts with varying fields of expertise* Assesses current state of this emerging and rapidly growing field

Download or read book Computer Simulations of Liquid Crystals and Polymers written by Paolo Pasini and published by Springer Science & Business Media. This book was released on 2005-08-11 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals, polymers and polymer liquid crystals are soft condensed matter systems of major technological and scientific interest. An understanding of the macroscopic properties of these complex systems and of their many and interesting peculiarities at the molecular level can nowadays only be attained using computer simulations and statistical mechanical theories. Both in the Liquid Crystal and Polymer fields a considerable amount of simulation work has been done in the last few years with various classes of models at different special resolutions, ranging from atomistic to molecular and coarse-grained lattice models. Each of the two fields has developed its own set of tools and specialized procedures and the book aims to provide a state of the art review of the computer simulation studies of polymers and liquid crystals. This is of great importance in view of a potential cross-fertilization between these connected areas which is particularly apparent for a number of experimental systems like, e.g. polymer liquid crystals and anisotropic gels where the different fields necessarily merge. An effort has been made to assess the possibilities of a coherent description of the themes that have developed independently, and to compare and extend the theoretical and computational techniques put forward in the different areas.

Download or read book Multi Scale Phenomena in Complex Fluids written by Thomas Y. Hou and published by World Scientific. This book was released on 2009 with total page 379 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-Scale Phenomena in Complex Fluids is a collection of lecture notes delivered during the first two series of mini-courses from OC Shanghai Summer School on Analysis and Numerics in Modern SciencesOCO, which was held in 2004 and 2006 at Fudan University, Shanghai, China. This review volume of 5 chapters, covering various fields in complex fluids, places emphasis on multi-scale modeling, analyses and simulations. It will be of special interest to researchers and graduate students who want to work in the field of complex fluids."

Download or read book Multiscale Simulation of Viscoelastic Flows written by Jason Ka-Chun Suen and published by . This book was released on 2003 with total page 726 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) Simulations of the original Doi model with the Maier-Saupe potential in a pressure-driven channel flow by Nayak showed disclination formation due to the shear-rate-dependent frequencies of the tumbling/wagging states of the Doi model in a shear or mixed shear flow. The lack of an instrinsic length scale in the model leads to an infinitesimal structure refinement that eventually causes numerical instabilities. In this thesis, the effect of concentration variation is incorporated to develop a modified Doi model for introducing an intrinsic length scale through translational diffusion. This changes the mathematical characteristics of the spatial variation of the underlying diffusion equation from that of a hyperbolic equation to that of an elliptic equation. The resulting elliptic diffusion equation is then solved by using a local discontinuous Galerkin method, where an auxillary variable is introduced to rewrite the elliptic diffusion equation into a pair of formal, hyperbolic equations, which in turn is solved by the standard discontinuous Galerkin method. Unlike the original Doi model, a steady state is reached for a variety of De. Although there is structure variation across the channel width, the director profiles point uniformly along the flow direction. The lack of disclination formation may be rectified by introducing Frank elasticity into the modified Doi model ...

Download or read book Multiscale Modeling of Structure property Relationships in Polymers with Heterogenous Structure written by Yiyang Li and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The exceptional mechanical properties of polymers with heterogeneous structure, such as the high toughness of polyethylene and the excellent blast-protection capability of polyurea, are strongly related to their morphology and nanoscale structure. Different polymer microstructures, such as semicrystalline morphology and segregated nanophases, lead to coordinated molecular motions during deformation in order to preserve compatibility between the different material phases. To study molecular relaxation in polyethylene, a coarse-grained model of polyethylene was calibrated to match the local structural variable distributions sampled from supercooled atomistic melts. The coarse-grained model accurately reproduces structural properties, e.g., the local structure of both the amorphous and crystalline phases, and thermal properties, e.g., glass transition and melt temperatures, and dynamic properties: including the vastly different relaxation time scales of the amorphous and crystalline phases. A hybrid Monte Carlo routine was developed to generate realistic semicrystalline configurations of polyethylene. The generated systems accurately predict the activation energy of the alpha relaxation process within the crystalline phase. Furthermore, the models show that connectivity to long chain segments in the amorphous phase increases the energy barrier for chain slip within crystalline phase. This prediction can guide the development of tougher semicrystalline polymers by providing a fundamental understanding of how nanoscale morphology contributes to chain mobility. In a different study, the macroscopic shock response of polyurea, a phase segregated copolymer, was analyzed using density functional theory (DFT) molecular dynamics (MD) simulations and classical MD simulations. The two models predict the shock response consistently up to shock pressures of 15 GPa, beyond which the DFT-based simulations predict a softer response. From the DFT simulations, an analysis of bond scission was performed as a first step in developing a more fundamental understanding of how shock induced material transformations effect the shock response and pressure dependent strength of polyurea subjected to extreme shocks.

Download or read book Liquid Crystal Elastomers written by Mark Warner and published by Oxford University Press. This book was released on 2007-04-05 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text is a primer for liquid crystals, polymers, rubber and elasticity. It is directed at physicists, chemists, material scientists, engineers and applied mathematicians at the graduate student level and beyond.

Download or read book Flow Visualization and Modeling of Liquid Crystalline Polymers written by Mark Naoshi Kawaguchi and published by . This book was released on 1998 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Liquid Crystalline Polymers written by A. M. Donald and published by Cambridge University Press. This book was released on 2006-05-11 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: A 2006 edition explaining the underlying science and applications of liquid crystalline polymers.

Download or read book Adaptive Multiscale Modeling of Polymeric Materials Using Goal oriented Error Estimation Arlequin Coupling and Goals Algorithms written by Paul Thomas Bauman and published by . This book was released on 2008 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific theories that explain how physical systems behave are described by mathematical models which provide the basis for computer simulations of events that occur in the physical universe. These models, being only mathematical characterizations of actual phenomena, are obviously subject to error because of the inherent limitations of all mathematical abstractions. In this work, new theory and methodologies are developed to quantify such modeling error in a special way that resolves a fundamental and standing issue: multiscale modeling, the development of models of events that transcend many spatial and temporal scales. Specifically, we devise the machinery for a posteriori estimates of relative modeling error between a model of fine scale and another of coarser scale, and we use this methodology as a general approach to multiscale problems. The target application is one of critical importance to nanomanufacturing: imprint lithography of semiconductor devices. The development of numerical methods for multiscale modeling has become one of the most important areas of computational science. Technological developments in the manufacturing of semiconductors hinge upon the ability to understand physical phenomena from the nanoscale to the microscale and beyond. Predictive simulation tools are critical to the advancement of nanomanufacturing semiconductor devices. In principle, they can displace expensive experiments and testing and optimize the design of the manufacturing process. The development of such tools rest on the edge of contemporary methods and high-performance computing capabilities and is a major open problem in computational science. In this dissertation, a molecular model is used to simulate the deformation of polymeric materials used in the fabrication of semiconductor devices. Algorithms are described which lead to a complex molecular model of polymer materials designed to produce an etch barrier, a critical component in imprint lithography approaches to semiconductor manufacturing. Each application of this so-called polymerization process leads to one realization of a lattice-type model of the polymer, a molecular statics model of enormous size and complexity. This is referred to as the base model for analyzing the deformation of the etch barrier, a critical feature of the manufacturing process. To reduce the size and complexity of this model, a sequence of coarser surrogate models is generated. These surrogates are the multiscale models critical to the successful computer simulation of the entire manufacturing process. The surrogate involves a combination of particle models, the molecular model of the polymer, and a coarse-scale model of the polymer as a nonlinear hyperelastic material. Coefficients for the nonlinear elastic continuum model are determined using numerical experiments on representative volume elements of the polymer model. Furthermore, a simple model of initial strain is incorporated in the continuum equations to model the inherit shrinking of the A coupled particle and continuum model is constructed using a special algorithm designed to provide constraints on a region of overlap between the continuum and particle models. This coupled model is based on the so-called Arlequin method that was introduced in the context of coupling two continuum models with differing levels of discretization. It is shown that the Arlequin problem for the particle-tocontinuum model is well posed in a one-dimensional setting involving linear harmonic springs coupled with a linearly elastic continuum. Several numerical examples are presented. Numerical experiments in three dimensions are also discussed in which the polymer model is coupled to a nonlinear elastic continuum. Error estimates in local quantities of interest are constructed in order to estimate the modeling error due to the approximation of the particle model by the coupled multiscale surrogate model. The estimates of the error are computed by solving an auxiliary adjoint, or dual, problem that incorporates as data the quantity of interest or its derivatives. The solution of the adjoint problem indicates how the error in the approximation of the polymer model inferences the error in the quantity of interest. The error in the quantity of interest represents the relative error between the value of the quantity evaluated for the base model, a quantity typically unavailable or intractable, and the value of the quantity of interest provided by the multiscale surrogate model. To estimate the error in the quantity of interest, a theorem is employed that establishes that the error coincides with the value of the residual functional acting on the adjoint solution plus a higher-order remainder. For each surrogate in a sequence of surrogates generated, the residual functional acting on various approximations of the adjoint is computed. These error estimates are used to construct an adaptive algorithm whereby the model is adapted by supplying additional fine-scale data in certain subdomains in order to reduce the error in the quantity of interest. The adaptation algorithm involves partitioning the domain and selecting which subdomains are to use the particle model, the continuum model, and where the two overlap. When the algorithm identifies that a region contributes a relatively large amount to the error in the quantity of interest, it is scheduled for refinement by switching the model for that region to the particle model. Numerical experiments on several configurations representative of nano-features in semiconductor device fabrication demonstrate the effectiveness of the error estimate in controlling the modeling error as well as the ability of the adaptive algorithm to reduce the error in the quantity of interest. There are two major conclusions of this study: 1. an effective and well posed multiscale model that couples particle and continuum models can be constructed as a surrogate to molecular statics models of polymer networks and 2. an error estimate of the modeling error for such systems can be estimated with sufficient accuracy to provide the basis for very effective multiscale modeling procedures. The methodology developed in this study provides a general approach to multiscale modeling. The computational procedures, computer codes, and results could provide a powerful tool in understanding, designing, and optimizing an important class of semiconductormanufacturing processes. The study in this dissertation involves all three components of the CAM graduate program requirements: Area A, Applicable Mathematics; Area B, Numerical Analysis and Scientific Computation; and Area C, Mathematical Modeling and Applications. The multiscale modeling approach developed here is based on the construction of continuum surrogates and coupling them to molecular statics models of polymer as well as a posteriori estimates of error and their adaptive control. A detailed mathematical analysis is provided for the Arlequin method in the context of coupling particle and continuum models for a class of one-dimensional model problems. Algorithms are described and implemented that solve the adaptive, nonlinear problem proposed in the multiscale surrogate problem. Large scale, parallel computations for the base model are also shown. Finally, detailed studies of models relevant to applications to semiconductor manufacturing are presented.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiscale Modeling of Multiphase Polymers written by William Brantley Lawrimore and published by . This book was released on 2016 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurately simulating material systems in a virtual environment requires the synthesis and utilization of all relevant information regarding performance mechanisms for the material occurring over a range of length and time scales. Multiscale modeling is the basis for the Integrated Computational Materials Engineering (ICME) Paradigm and is a powerful tool for accurate material simulations. However, while ICME has experienced adoption among those in the metals community, it has not gained traction in polymer research. This thesis seeks establish a hierarchical multiscale modeling methodology for simulating polymers containing secondary phases. The investigation laid out in the chapters below uses mesoscopic Finite Element Analysis (FEA) as a foundation to build a multiscale modeling methodology for polymer material systems. At the mesoscale a Design of Experiments (DOE) parametric study utilizing FEA of polymers containing defects compared the relative impacts of a selection of parameters on damage growth and coalescence in polymers. Of the parameters considered, the applied stress state proved to be the most crucial parameter affecting damage growth and coalescence. At the macroscale, the significant influence of the applied stress state on damage growth and coalescence in polymers (upscaled from the mesoscale) motivated an expansion of the Bouvard Internal State Variable (ISV) (Bouvard et al. 2013) polymer model stress state sensitivity. Deviatoric stress invariants were utilized to modify the Bouvard ISV model to account for asymmetry in polymer mechanical performance across different stress states (tension, compression, torsion). Lastly, this work implements a hierarchical multiscale modeling methodology to examine parametric effects of heterogeneities on Polymer/Clay Nanocomposite’s (PCNs) mechanical performance under uncertainty. A Virtual Composite Structure Generator (VCSG) built three-dimensional periodic Representative Volume Elements (RVEs) coupled to the Bouvard ISV model and a Cohesive Zone Model (CZM) which featured a Traction-Separation (T-S) rule calibrated to results upscaled from Molecular Dynamics (MD) simulations. A DOE parametric examination utilized the RVEs to determine the relative effects of a selection of parameters on the mechanical performance of PCNs. DOE results determined that nanoclay particle orientation was the most influential parameter affecting PCN elastic modulus while intercalated interlamellar gallery strength had the greatest influence on PCN yield stress.

Download or read book Liquid Crystalline and Mesomorphic Polymers written by Valery P. Shibaev and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the various new directions in modern polymer science, the design and investigation of liquid crystal (LC) polymers have been the ones growing most actively and fruitfully. In spite of that, the possible formation of an anisotropic LC phase was only demonstrated theoretically for the first time in the 1950s by Onsager [1] and Flory [2], and then experimentally verified in the studies with polypeptides solutions. In essence, the studies of these LC lyotropic systems did not deviate from the theme of purely academic interest. It was at the beginning of the 1970s that the experimental "explosion" occurred, when aromatic polyamides were synthesized and their ability to form LC solutions in certain very aggressive solvents was discovered. The search for practical applications of such LC systems was crowned with the successful creation of the new generation of ultrastrong high-modulus ther mostable fibers, such as the Kevlar, due to the high degree of order of the macromolecules in the anisotropic LC state. In fact, these investigations coincided with the swift emergence on the practical "scene" of thermotropic low-molar-mass liquid crystals, with the use of these materials in microelectronics and electro optics (figures and let ters indicators, displays in personal computers, and flat TV, etc.). Polymer scientists also began to develop methods of synthesizing thermotropic LC polymers by incorporating mesogenic fragments in the main (main-chain LC polymers) or side branchings of the macromolecules (side-chain or comb shaped polymers).

Download or read book Flows in Polymers Reinforced Polymers and Composites written by Christophe Binetruy and published by Springer. This book was released on 2015-03-30 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a detailed and practical introduction to complex flows of polymers and reinforced polymers as well as the flow of simple fluids in complex microstructures. Over the last decades, an increasing number of functional and structural parts, made so far with metals, has been progressively reengineered by replacing metallic materials by polymers, reinforced polymers and composites. The motivation for this substitution may be the weight reduction, the simpler, cheaper or faster forming process, or the ability to exploit additional functionalities. The present Brief surveys modern developments related to the multi-scale modeling and simulation of polymers, reinforced polymers, that involve a flowing microstructure and continuous fiber-reinforced composites, wherein the fluid flows inside a nearly stationary multi-scale microstructure. These developments concern both multi-scale modeling, defining bridges between the micro and macro scales - with special emphasis on the mesoscopic scale at which kinetic theory descriptions apply and advanced simulation techniques able to address efficiently the ever more complex and detailed models defined at different scales. This book is addressed to students (Master and doctoral levels), researchers and professionals interested in computational rheology and material forming processes involving polymers, reinforced polymers and composites. It provides a unique coverage of the state of the art in these multi-disciplinary fields.

Download or read book Liquid Crystalline Polymers written by Division on Engineering and Physical Sciences and published by National Academies Press. This book was released on 1990-02-01 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: