Numerical Simulation of Pore-scale Heterogeneity and Its Effects on Elastic, Electrical and Transport Properties

Numerical Simulation of Pore-scale Heterogeneity and Its Effects on Elastic, Electrical and Transport Properties
Author: Ratnanabha Sain
Publisher: Stanford University
Total Pages: 224
Release: 2010
Genre:
ISBN:

This dissertation describes numerical experiments quantifying the influence of pore-scale heterogeneities and their evolution on macroscopic elastic, electrical and transport properties of porous media. We design, implement and test a computational recipe to construct granular packs and consolidated microstructures replicating geological processes and to estimate the link between process-to-property trends. This computational recipe includes five constructors: a Granular Dynamics (GD) simulation, an Event Driven Molecular Dynamics (EDMD) simulation and three computational diagenetic schemes; and four property estimators based on GD for elastic, finite-elements (FE) for elastic and electrical conductivity, and Lattice-Boltzmann method (LBM) for flow property simulations. Our implementation of GD simulation is capable of constructing realistic, frictional, jammed sphere packs under isotropic and uniaxial stress states. The link between microstructural properties in these packs, like porosity and coordination number (average number of contacts per grain), and stress states (due to compaction) is non-unique and depends on assemblage process and inter-granular friction. Stable jammed packs having similar internal stress and coordination number (CN) can exist at a range of porosities (38-42%) based on how fast they are assembled or compressed. Similarly, lower inter-grain friction during assemblage creates packs with higher coordination number and lower porosity at the same stress. Further, the heterogeneities in coordination number, spatial arrangement of contacts, the contact forces and internal stresses evolve with compaction non-linearly. These pore-scale heterogeneities impact effective elastic moduli, calculated by using infinitesimal perturbation method. Simulated stress-strain relationships and pressure-dependent elastic moduli for random granular packs show excellent match with laboratory experiments, unlike theoretical models based on Effective Medium Theory (EMT). We elaborately discuss the reasons why Effective Medium Theory (EMT) fails to correctly predict pressure-dependent elastic moduli, stress-strain relationships and stress-ratios (in uniaxial compaction) of granular packs or unconsolidated sediments. We specifically show that the unrealistic assumption of homogeneity in disordered packs and subsequent use of continuum elasticity-based homogeneous strain theory creates non-physical packs, which is why EMT fails. In the absence of a rigorous theory which can quantitatively account for heterogeneity in random granular packs, we propose relaxation corrections to amend EMT elastic moduli predictions. These pressure-dependent and compaction-dependent (isotropic or uniaxial) correction factors are rigorously estimated using GD simulation without non-physical approximations. Further, these correction factors heuristically represent the pressure-dependent heterogeneity and are also applicable for amending predictions of theoretical cementation models, which are conventionally used for granular packs. For predicting stress-ratios in uniaxial compaction scenario, we show the inappropriateness of linear elasticity-based equations, which use elastic constants only and do not account for dissipative losses like grain sliding. We further implement and test a computational recipe to construct consolidated microstructures based on different geological scenarios, like sorting, compaction, cementation types and cement materials. Our diagenetic trends of elastic, electrical and transport properties show excellent match with laboratory experiments on core plugs. This shows the feasibility of implementing a full-scale computational-rock-physics-based laboratory to construct and estimate properties based on geological processes. However, the elastic property estimator (FE simulation) shows limitations of finite resolution while computing elastic properties of unconsolidated sediments and fluid-saturated microstructures.

Nanotechnology-Driven Engineered Materials

Nanotechnology-Driven Engineered Materials
Author: Sabu Thomas
Publisher: CRC Press
Total Pages: 400
Release: 2018-09-03
Genre: Science
ISBN: 1351592580

Nanostructured materials are emerging as a new class of materials that exhibit unique microstructures and enhanced mechanical performance. As an outcome of this, these materials have attracted considerable attention in scientific communities all over the world. There is continuous research to facilitate product development, thereby improving product quality and reliability in industry. This volume is devoted to novel architectures at the nano-level with an emphasis on new synthesis and characterization methods. Special emphasis is given to new applications of nanostructures and nanocomposites in various fields, such as nano-electronics, energy conversion, catalysis, drug delivery and nano-medicine. The chapters are divided into sections focusing on: Nanoparticles Assembly and Nanostructured Materials Nanocomposites Properties Nanostructured Materials for Biomedical Applications

Solid State Ionics: Materials & Devices, Procs Of The 7th Asian Conf

Solid State Ionics: Materials & Devices, Procs Of The 7th Asian Conf
Author: B V R Chowdari
Publisher: World Scientific
Total Pages: 778
Release: 2000-10-27
Genre: Science
ISBN: 9814491918

Solid state ionics, being a multidisciplinary area, is expected to grow at a faster rate in the new millennium, prompting the discovery of new materials and devices, as well as helping to optimize the known devices, especially the portable power sources and display systems. The Asian Society for Solid State Ionics (ASSSI) plays a significant role in bringing together researchers from the Asian countries, every two years, to exchange notes and ideas, to foster friendship and collaboration, and to discuss the prospects.The topics covered in this volume are: ion dynamics, theoretical modeling, ion-conducting polymers, gels and ceramics, glasses, crystalline materials including nano-phases, composites, electrode/electrolyte interfaces and novel experimental techniques. Papers on crystalline materials deal with ion conduction in Li, Na, Ag, Tl, F and O-containing compounds. Materials and device aspects have received wide coverage, especially the areas of lithium ion batteries (LIBs) and solid oxide fuel cells (SOFCs).Rechargeable high energy density LIBs, especially those employing immobilized gel or polymer electrolyte, are the favorite portable power sources in the new millennium. As expected, a large number of papers on both cathodes and polymer electrolytes for LIBs were presented at the conference. The papers on fuel cells almost exclusively deal with SOFCs, indicating the great importance being given to this area in Japan and China. A breakthrough in materials and technology of SOFC is expected in the coming decade. This volume will be useful not only to the active researchers in the field but also to youngsters entering the exciting area of solid state ionics.

Ceramic Materials and Multilayer Electronic Devices

Ceramic Materials and Multilayer Electronic Devices
Author: K. M. Nair
Publisher: John Wiley & Sons
Total Pages: 496
Release: 2012-04-11
Genre: Technology & Engineering
ISBN: 1118406761

This volume contains a collection of 40 papers from two symposia: Advanced Dielectric Materials and Multilayer Electronic Devices and High Strain Piezoelectric Materials, Devices and Applications. Topics include fundamental and historical perspectives of dielectric materials; relaxor materials and devices; high strain piezoelectric devices; advanced aspects of powder preparation, characterization, and properties; thin films; materials for low and high frequency applications; processing-structure-property-relationships; and future applications. Proceedings of the symposium held at the 105th Annual Meeting of The American Ceramic Society, April 27-30, 2003, in Nashville, Tennessee; Ceramic Transactions, Volume 150.

Solid State Ionics

Solid State Ionics
Author: B. V. R. Chowdari
Publisher: World Scientific
Total Pages: 784
Release: 2000
Genre: Technology & Engineering
ISBN: 9789810244927

Solid atate ionics, being a multidisciplinary area, is expected to grow at a faster rate in the new millennium, prompting the discovery of new materials and devices, as well as helping to optimize the known devices, especially the portable power sources and display systems. The Asian Society for Solid State Ionics (ASSSI) plays a significant role in bringing together researchers from the Asian countries, every two years, to exchange notes and ideas, to foster friendship and collaboration, and to discuss the prospects. The topics covered in this volume are: ion dynamics, theoretical modeling, ion-conducting polymers, gels and ceramics, glasses, crystalline materials including nano-phases, composites, electrode/electrolyte interfaces and novel experimental techniques. Papers on crystalline materials deal with ion conduction in Li, Na, Ag, Tl, F and O-containing compounds. Materials and device aspects have received wide coverage, especially the areas of lithium ion batteries (LIBs) and solid oxidefuel cells,(SOFCs). Rechargeable high energy density LIBs, especially those employing immobilized gel or polymer electrolyte, are the favorite portable power sources in the new millennium. As expected, a large number of papers on both cathodes and polymer electrolytes for LIBs were presented at the conference. The papers on fuel cells almost exclusively deal with SOFCs, indicating the great importance being given to this area in Japan and China. A breakthrough in materials and technology of SOFC is expected in the coming decade. This volume will be useful not only to the active researchers in the field but also to youngsters entering the exciting area of solid state ionics.

Electrical Conductivity in Polymer-Based Composites

Electrical Conductivity in Polymer-Based Composites
Author: Reza Taherian
Publisher: William Andrew
Total Pages: 434
Release: 2018-11-30
Genre: Technology & Engineering
ISBN: 012812542X

Electrical Conductivity in Polymer-Based Composites: Experiments, Modelling and Applications offers detailed information on all aspects of conductive composites. These composites offer many benefits in comparison to traditional conductive materials, and have a broad range of applications, including electronic packaging, capacitors, thermistors, fuel cell devices, dielectrics, piezoelectric functions and ferroelectric memories. Sections cover the theory of electrical conductivity and the different categories of conductive composites, describing percolation threshold, tunneling effect and other phenomena in the field. Subsequent chapters present thorough coverage of the key phases in the development and use of conductive composites, including manufacturing methods, external parameters, applications, modelling and testing methods. This is an essential source of information for materials scientists and engineers working in the fields of polymer technology, processing and engineering, enabling them to improve manufacture and testing methods, and to benefit fully from applications. The book also provides industrial and academic researchers with a comprehensive and up-to-date understanding of conductive composites and related issues. - Explains the methods used in the manufacture and testing of conductive composites, and in the modeling of electrical conductivity - Contains specialized information on the full range of applications for conductive composites, including conductive adhesives or pastes - Brings scientists, engineers and researchers up-to-date with the latest advances in the field

Immittance Spectroscopy

Immittance Spectroscopy
Author: Mohammad A. Alim
Publisher: John Wiley & Sons
Total Pages: 427
Release: 2017-12-27
Genre: Science
ISBN: 1119185424

This book emphasizes the use of four complex plane formalisms (impedance, admittance, complex capacitance, and modulus) in a simultaneous fashion. The purpose of employing these complex planes for handling semicircular relaxation using a single set of measured impedance data (ac small-signal electrical data) is highly underscored. The current literature demonstrates the importance of template version of impedance plot whereas this book reflects the advantage of using concurrent four complex plane plots for the same data. This approach allows extraction of a meaningful equivalent circuit model attributing to possible interpretations via potential polarizations and operative mechanisms for the investigated material system. Thus, this book supersedes the limitations of the impedance plot, and intends to serve a broader community of scientific and technical professionals better for their solid and liquid systems. This book addresses the following highlighted contents for the measured data but not limited to the:- (1) Lumped Parameter/Complex Plane Analysis (LP/CPA) in conjunction with the Bode plots; (2) Equivalent circuit model (ECM) derived from the LP/CPA; (3) Underlying Operative Mechanisms along with the possible interpretations; (4) Ideal (Debye) and non-ideal (non-Debye) relaxations; and (5) Data-Handling Criteria (DHC) using Complex Nonlinear Least Squares (CNLS) fitting procedures.

Localized In-situ Methods for Investigating Eletrochemical Interfaces

Localized In-situ Methods for Investigating Eletrochemical Interfaces
Author: S. Ray Taylor
Publisher:
Total Pages: 418
Release: 2000
Genre: Science
ISBN:

The 31 papers discuss various methods for analyzing electrochemical interfaces to find and identify local phenomena such as corrosion, electrocrystallization, electrocatalysis, and membrane-based separations that might affect the electrochemical process. The methods include atomic force and scanning tunneling microscopy, optical methods, scanning electrochemical microscopy, local impedance and current, and scanning Kelvin probe. c. Book News Inc.