Interfacial Boundary Conditions In Multiscale Simulation Of Nano Materials

Since their discovery, carbon nanotubes have stirred an ever-growing interest among researchers due to their distinct physical properties. A number of experimental studies and computer simulation methods have led to a numerical estimate of their remarkable mechanical and electronic properties and has opened a possibility of their use in a variety of fields. The high cost of experimental studies and computational limitations of conventional single scale analyses of carbon nanotubes have further motivated researchers to explore multiscale techniques to understand of the physics of their behavior. In this thesis, we have discussed an analytical approach to formulate multi-scale boundary conditions for quasistatic atomistic simulations of these geometrically periodic nanostructures. The nanotubes are virtually divided into coarse and fine scale regions and atomistic simulation is used only in the fine scale region. In the periodic coarse scale region, we use Discrete Fourier Transform to yield a compact formulation, in terms of the discrete convolution operators, that represents the response behavior of the coarse scale domain upon the fine/coarse scale interface. This approach facilitates use of computer simulations for the fine scale, without the requirement to model the entire coarse scale domain thus holding potential to drastic savings in computational time up to several orders of magnitude. The robustness of the proposed multi-scale method is evident after comparison and verification of our results with bench-mark results from fully atomistic simulations under application of realistic boundary conditions.

Multiscale Simulations and Mechanics of Biological Materials A compilation of recent developments in multiscale simulation and computational biomaterials written by leading specialists in the field Presenting the latest developments in multiscale mechanics and multiscale simulations, and offering a unique viewpoint on multiscale modelling of biological materials, this book outlines the latest developments in computational biological materials from atomistic and molecular scale simulation on DNA, proteins, and nano-particles, to meoscale soft matter modelling of cells, and to macroscale soft tissue and blood vessel, and bone simulations. Traditionally, computational biomaterials researchers come from biological chemistry and biomedical engineering, so this is probably the first edited book to present work from these talented computational mechanics researchers. The book has been written to honor Professor Wing Liu of Northwestern University, USA, who has made pioneering contributions in multiscale simulation and computational biomaterial in specific simulation of drag delivery at atomistic and molecular scale and computational cardiovascular fluid mechanics via immersed finite element method. Key features: Offers a unique interdisciplinary approach to multiscale biomaterial modelling aimed at both accessible introductory and advanced levels Presents a breadth of computational approaches for modelling biological materials across multiple length scales (molecular to whole-tissue scale), including solid and fluid based approaches A companion website for supplementary materials plus links to contributors’ websites (www.wiley.com/go/li/multiscale)

In this chapter, a hierarchical multiscale approach for modeling carbon nanotube (CNT) composites using molecular dynamics (MD) at the nanoscale and the boundary element method (BEM) at the microscale is presented. First, the current status in modeling and simulations of CNT composites is reviewed. Then, the basics of MD are introduced and the modeling techniques using MD at the nanoscale to extract the CNT properties and a cohesive interface model for CNT/polymer composites are discussed. Next, the boundary integral equations (BIEs) governing the displacement and stress fields in fiber-reinforced composite models at the microscale are presented. The BEM applied to solve the BIEs numerically is discussed and the fast multipole BEM techniques that are suitable for solving large-scale models are presented. In the numerical studies, parameters in the cohesive interface model are obtained by conducting CNT pull-out simulations with MD and these parameters are subsequently used in the BEM models of the CNT/polymer composites. Marked decreases of the estimated effective Young's moduli are observed using the new BEM models with the cohesive interface conditions as compared with earlier models with perfect bonding interface conditions. The developed BEM models combined with the MD can be a very useful tool for studying interface effects in CNT composites and for large-scale characterizations of such nanocomposites. Future efforts and directions in the research on modeling nanocomposites are offered to conclude this chapter.

This book presents current spatial and temporal multiscaling approaches of materials modeling. Recent results demonstrate the deduction of macroscopic properties at the device and component level by simulating structures and materials sequentially on atomic, micro- and mesostructural scales. The book covers precipitation strengthening and fracture processes in metallic alloys, materials that exhibit ferroelectric and magnetoelectric properties as well as biological, metal-ceramic and polymer composites. The progress which has been achieved documents the current state of art in multiscale materials modelling (MMM) on the route to full multi-scaling. Contents: Part I: Multi-time-scale and multi-length-scale simulations of precipitation and strengthening effects Linking nanoscale and macroscale Multiscale simulations on the coarsening of Cu-rich precipitates in α-Fe using kinetic Monte Carlo, Molecular Dynamics, and Phase-Field simulations Multiscale modeling predictions of age hardening curves in Al-Cu alloys Kinetic Monte Carlo modeling of shear-coupled motion of grain boundaries Product Properties of a two-phase magneto-electric composite Part II: Multiscale simulations of plastic deformation and fracture Niobium/alumina bicrystal interface fracture Atomistically informed crystal plasticity model for body-centred cubic iron FE2AT ・ finite element informed atomistic simulations Multiscale fatigue crack growth modeling for welded stiffened panels Molecular dynamics study on low temperature brittleness in tungsten single crystals Multi scale cellular automata and finite element based model for cold deformation and annealing of a ferritic-pearlitic microstructure Multiscale simulation of the mechanical behavior of nanoparticle-modified polyamide composites Part III: Multiscale simulations of biological and bio-inspired materials, bio-sensors and composites Multiscale Modeling of Nano-Biosensors Finite strain compressive behaviour of CNT/epoxy nanocomposites Peptide・zinc oxide interaction

This research is a concerted team effort to investigate the multiscale behavior of materials systems made of nano-materials or nano/bulk-materials. The fundamental understanding of multiscale behavior is the key to the utilization of nano-materials and to the design of material systems contained nano-materials. The research program represents a synergistic effort to investigate different aspects of multiscale phenomena using the computational approaches by a team composed of researchers from AFRL-ML, NCCU of Taiwan and US universities. Mixed atomistic and continuum methods offer the possibility of carrying out simulations of material properties at both larger length scales and longer times than direct atomistic calculations. The proposed innovative algorithm links atomistic and continuum models through the device of the finite element method which permits a reduction of the full set of atomistic degrees of freedom. This research gives a full description of the proposed innovative algorithm with special reference to the ways in which the method may be used to model crystals with more than a single grain. In this project, we have developed the innovative algorithms in the area of nanomechanics. These approaches were used to studies the nanoindentation size effect, mechanical properties of nanotubes, the effect of adsorbed layers on the mechanical properties of thin films, and the asperity contact at nano-scale interfaces.

Due to their small size and their dependence on very fast phenomena, nanomaterials are ideal systems for computational modelling. This book provides an overview of various nanosystems classified by their dimensions: 0D (nanoparticles, QDs, etc.), 1D (nanowires, nanotubes), 2D (thin films, graphene, etc.), 3D (nanostructured bulk materials, devices). Fractal dimensions, such as nanoparticle agglomerates, percolating films and combinations of materials of different dimensionalities are also covered (e.g. epitaxial decoration of nanowires by nanoparticles, i.e. 0D+1D nanomaterials). For each class, the focus will be on growth, structure, and physical/chemical properties. The book presents a broad range of techniques, including density functional theory, molecular dynamics, non-equilibrium molecular dynamics, finite element modelling (FEM), numerical modelling and meso-scale modelling. The focus is on each method’s relevance and suitability for the study of materials and phenomena in the nanoscale. This book is an important resource for understanding the mechanisms behind basic properties of nanomaterials, and the major techniques for computational modelling of nanomaterials. Explores the major modelling techniques used for different classes of nanomaterial Assesses the best modelling technique to use for each different type of nanomaterials Discusses the challenges of using certain modelling techniques with specific nanomaterials

This work gives a modern, up-to-date account of recent developments in computational multiscale mechanics. Both upscaling and concurrent computing methodologies will be addressed for a range of application areas in computational solid and fluid mechanics: Scale transitions in materials, turbulence in fluid-structure interaction problems, multiscale/multilevel optimization, multiscale poromechanics. A Dutch-German research group that consists of qualified and well-known researchers in the field has worked for six years on the topic of computational multiscale mechanics. This text provides a unique opportunity to consolidate and disseminate the knowledge gained in this project. The addition of chapters written by experts outside this working group provides a broad and multifaceted view of this rapidly evolving field.

Trends in Computational Nanomechanics reviews recent advances in analytical and computational modeling frameworks to describe the mechanics of materials on scales ranging from the atomistic, through the microstructure or transitional, and up to the continuum. The book presents new approaches in the theory of nanosystems, recent developments in theoretical and computational methods for studying problems in which multiple length and/or time scales must be simultaneously resolved, as well as example applications in nanomechanics. This title will be a useful tool of reference for professionals, graduates and undergraduates interested in Computational Chemistry and Physics, Materials Science, Nanotechnology.

Presenting cutting-edge research and development within multiscale modeling techniques and frameworks, Multiscale Analysis of Deformation and Failure of Materials systematically describes the background, principles and methods within this exciting new & interdisciplinary field. The author’s approach emphasizes the principles and methods of atomistic simulation and its transition to the nano and sub-micron scale of a continuum, which is technically important for nanotechnology and biotechnology. He also pays close attention to multiscale analysis across the micro/meso/macroscopy of a continuum, which has a broad scope of applications encompassing different disciplines and practices, and is an essential extension of mesomechanics. Of equal interest to engineers, scientists, academics and students, Multiscale Analysis of Deformation and Failure of Materials is a multidisciplinary text relevant to those working in the areas of materials science, solid and computational mechanics, bioengineering and biomaterials, and aerospace, automotive, civil, and environmental engineering. Provides a deep understanding of multiscale analysis and its implementation Shows in detail how multiscale models can be developed from practical problems and how to use the multiscale methods and software to carry out simulations Discusses two interlinked categories of multiscale analysis; analysis spanning from the atomistic to the micro-continuum scales, and analysis across the micro/meso/macro scale of continuum.