Download or read book Granular Materials at Meso scale written by Bernard Cambou and published by Elsevier. This book was released on 2016-08-19 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Granular Materials at Meso-scale: Towards a Change of Scale Approach proposes a new way for developing an efficient change of scale—considering a meso-scale defined at the level of local arrays of particles. The change of scale is known to be a very interesting way to improve the modelling of mechanical behavior granular materials. In the past, studies have been proposed using a micro-scale at the grain level to perform change of scale, but limitations have been proven for these approaches. Definition and analysis of the phases are detailed, constituted by sets of meso-domains sharing the same texture characteristics. The authors propose a local constitutive model for the phases, allowing the constitutive model of the representative elementary volume to be definied from a change-of-scale approach and, finally, presenting the validation of obtained modeling on cyclic loadings. Proposes a new way for developing an efficient change of scale—considering a meso-scale Explores local meso-domains and texture characteristics Defines meso-strain and stress Analyzes the evolution of these variables and texture characteristics in relation to the applied loading

Download or read book Meso scale Framework for Modeling Granular Material Using Computed Tomography written by and published by . This book was released on 2016 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical modeling of unconsolidated granular materials is comprised of multiple nonlinear phenomena. Accurately capturing these phenomena, including grain deformation and intergranular forces depends on resolving contact regions several orders of magnitude smaller than the grain size. Here, we investigate a method for capturing the morphology of the individual particles using computed X-ray and neutron tomography, which allows for accurate characterization of the interaction between grains. The ability of these numerical approaches to determine stress concentrations at grain contacts is important in order to capture catastrophic splitting of individual grains, which has been shown to play a key role in the plastic behavior of the granular material on the continuum level. Discretization approaches, including mesh refinement and finite element type selection are presented to capture high stress concentrations at contact points between grains. The effect of a grain's coordination number on the stress concentrations is also investigated.

Download or read book Mesoscale Simulations of Granular Materials with Peridynamics written by and published by . This book was released on 2011 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computational Studies of a Mesoscale Thermodynamics of Granular Materials written by Radhika S. Saksena and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mesoscale Modeling and Direct Simulation of Explosively Dispersed Granular Materials written by Huangrui Mo and published by . This book was released on 2019 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explosively dispersed granular materials frequently exhibit macroscale coherent particle clustering and jetting structures. The underlying mechanism is of significant interest to study instability and mixing in high-speed gas-solid flows but remains unclear, primarily attributed to the complex mesoscale multiphase interactions involved in the dispersal process. In order to advance the understanding of particle clustering and jetting instabilities, this thesis establishes a numerical framework for solving interface-resolved gas-solid flows with non-deforming bodies that are able to move, contact, and collide. The developed framework is implemented to create a computational solver and then verified using a variety of gas-solid flow problems at different geometric scales. Employing the developed framework and solver, this thesis further studies the particle clustering and jetting instabilities in explosively dispersed granular materials. A Cartesian, 3D, high-resolution, parallelized, gas-solid flow solver is created with the capability of tackling shocked flow conditions, irregular and moving geometries, and multibody collisions. The underlying numerical framework integrates operator splitting for partitioned fluid-solid interaction in the time domain, 2nd/3rd order strong stability-preserving Runge--Kutta methods and 3rd/5th order weighted essentially nonoscillatory schemes for high-resolution tempo-spatial discretization, the front-tracking method for evolving phase interfaces, a new field function developed for facilitating the solution of complex and dynamic fluid-solid systems on Cartesian grids, a new collision model developed for deterministic multibody contact and collision with parameterized coefficients of restitution and friction, and a new immersed boundary method developed for treating arbitrarily irregular and moving boundaries. The developed framework and solver are able to accurately, efficiently, and robustly solve coupled fluid-fluid, fluid-solid, and solid-solid interactions with flow conditions ranging from subsonic to hypersonic states. Employing the developed framework and solver, direct simulations that capture interface-resolved multiphase interactions and deterministic mesoscale granular dynamics are conducted to investigate particle clustering and jetting instabilities. A random sampling algorithm is employed to generate stochastic payload morphologies with randomly distributed particle positions and sizes. Through solving and analyzing cases that cover a set of stochastic payloads, burster states, and coefficients of restitution, a valid statistical dissipative property of the framework in solving explosively dispersed granular materials with respect to Gurney velocity is demonstrated. The predicted surface expansion velocities can extend the time range of the velocity scaling law with regard to Gurney energy in the Gurney theory from the steady-state termination phase to the unsteady evolution phase. When considering the mean surface expansion velocities, the maximum error of the unsteady velocity scaling law is about $0.792\%$ among the investigated Gurney energies. In addition, a dissipation analysis of the current discrete modeling of granular payloads suggests that incorporating the effects of porosity can enhance the prediction of Gurney velocity for explosively dispersed granular payloads. On the basis of direct simulations, an explanation for particle clustering and jetting instabilities is proposed to increase the understanding of established experimental observations in the literature. Results suggest that the development of internal sliding and colliding lines in the shock-compacted granular payload can be critical to the subsequent fracture pattern of the payload. Particle clusters manifested through payload fracture are then maintained by local pressure gradient between surrounding and interstitial flows as well as by dissipative inter-grain collisions. The existence of stable clusters introduce a more non-equilibrium momentum distribution in the overall payload, exhibiting as a form of clustering instability. Under the current assumptions of non-deformable grains, the mesoscale granular dynamics largely depends on the payload morphology as a result of packing methods. Different payload morphologies can develop varied sliding and colliding lines, which lead to a corresponding pattern for payload fracturing and particle clustering. With the rapid development of high-performance computing technology, future direct simulations on stochastic payloads with significantly increased domain sizes, number of particles, and solution times are expected to lead to a better understanding of the flow instability in explosively dispersed granular payloads. It is suggested that statistics collected from a large number of mesoscale computations based on random payload morphologies can potentially evolve into a macroscopic theory of multiphase flow instability for particle clustering and jetting phenomena widely observed in many areas involving dense gas-solid flows.

Download or read book Shock Phenomena in Granular and Porous Materials written by Tracy J. Vogler and published by Springer Nature. This book was released on 2019-09-04 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Granular forms of common materials such as metals and ceramics, sands and soils, porous energetic materials (explosives, reactive mixtures), and foams exhibit interesting behaviors due to their heterogeneity and critical length scale, typically commensurate with the grain or pore size. Under extreme conditions of impact, granular and porous materials display highly localized phenomena such as fracture, inelastic deformation, and the closure of voids, which in turn strongly influence the bulk response. Due to the complex nature of these interactions and the short time scales involved, computational methods have proven to be powerful tools to investigate these phenomena. Thus, the coupled use of experiment, theory, and simulation is critical to advancing our understanding of shock processes in initially porous and granular materials. This is a comprehensive volume on granular and porous materials for researchers working in the area of shock and impact physics. The book is divided into three sections, where the first presents the fundamentals of shock physics as it pertains to the equation of state, compaction, and strength properties of porous materials. Building on these fundamentals, the next section examines several applications where dynamic processes involving initially porous materials are prevalent, focusing on the areas of penetration, planetary impact, and reactive munitions. The final section provides a look at emerging areas in the field, where the expansion of experimental and computational capabilities are opening the door for new opportunities in the areas of advanced light sources, molecular dynamics modeling, and additively manufactured porous structures. By intermixing experiment, theory, and simulation throughout, this book serves as an excellent, up-to-date desk reference for those in the field of shock compression science of porous and granular materials.

Download or read book A study of mesoscale simulations for planar shock experiments on heterogeneous granular materials written by Merit G. Schumaker and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 3D Multi scale Behavior of Granular Materials Using Experimental and Numerical Techniques written by Andrew Druckrey and published by . This book was released on 2016 with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: Constitutive modeling of granular material behavior has generally been based on global response of laboratory-size specimens or larger models with little understanding of the fundamental mechanics that drive the global response. Many studies have acknowledged the importance of micro-scale and meso-scale mechanics on the constitutive behavior of granular materials. However, much knowledge is still missing to develop and improve robust micromechanical constitutive models. The research in this dissertation contributes to this knowledge gap for many potential applications using novel experimental techniques to investigate the three-dimensional (3D) behavior of granular materials. Critical micromechanics measurements at multiple scales are investigated by combining 3D synchrotron micro-computed tomography (SMT), 3D image analysis, and finite element analysis (FEA). At the single particle level (micro-scale), particle fracture was examined at strain rates of 0.2 mm/min and 2 m/s using quasi-static unconfined compression, unconfined mini-Kolsky bar, and x-ray imaging techniques. Surface reconstructions of particles were generated and exported to Abaqus FEA software, where quasi-static and higher rate loading curves and crack propagation were simulated with good accuracy. Stress concentrations in oddly shaped particles during FEA simulations resulted in more realistic fracture stresses than theoretical models. A nonlinear multivariable statistical model was developed to predict force required to fracture individual particles with known internal structure and loading geometry. At the meso-scale, 3D SMT imaging during in-situ triaxial testing of granular materials were used to identify particle morphology, contacts, kinematics and interparticle behavior. Micro shear bands (MSB) were exposed during pre-peak stress using a new relative particle displacement concept developed in this dissertation. MSB for spherical particles (glass beads) had larger thickness (3d50 to 5d50) than that of angular sands (such as F35 Ottawa sand, MSB thickness of 1d50 to 3d50). Particle morphology also plays a significant role in the onset and growth of shear bands and global fabric evolution of granular materials. More spherical particles typically exhibit more homogeneous internal anisotropy. Fabric of particles within the shear band (at higher densities and confining pressures) exhibits a peak and decrease into steady-state. Also, experimental fabric produces more accurate strength and deformation predictions in constitutive models that incorporate fabric evolution.

Download or read book Advances in Multi Physics and Multi Scale Couplings in Geo Environmental Mechanics written by Francois Nicot and published by Elsevier. This book was released on 2017-11-20 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Multi-Physics and Multi-Scale Couplings in Geo-Environmental Mechanics reunites some of the most recent work from the French research group MeGe GDR (National Research Group on Multiscale and Multiphysics Couplings in Geo-Environmental Mechanics) on the theme of multi-scale and multi-physics modeling of geomaterials, with a special focus on micromechanical aspects. Its offers readers a glimpse into the current state of scientific knowledge in the field, together with the most up-to-date tools and methods of analysis available. Each chapter represents a study with a different viewpoint, alternating between phenomenological/micro-mechanically enriched and purely micromechanical approaches. Throughout the book, contributing authors will highlight advances in geomaterials modeling, while also pointing out practical implications for engineers. Topics discussed include multi-scale modeling of cohesive-less geomaterials, including multi-physical processes, but also the effects of particle breakage, large deformations on the response of the material at the specimen scale and concrete materials, together with clays as cohesive geomaterials. The book concludes by looking at some engineering problems involving larger scales. Identifies contributions in the field of geomechanics Focuses on multi-scale linkages at small scales Presents numerical simulations by discrete elements and tools of homogenization or change of scale

Download or read book Mesoscale Modeling in Chemical Engineering Part II written by and published by Academic Press. This book was released on 2016-02-16 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mesoscale Modeling in Chemical Engineering, a volume in the Advances in Chemical Engineering series provides the reader with personal views of authorities in the field. Subjects covered are not limited to the classical chemical engineering disciplines, with contributions connecting chemical engineering to related scientific fields, thus providing new ideas for additional thought. The book balances well developed areas such as process industry, transformation of materials, energy, and environmental issues with areas where applications of chemical engineering are more recent or emerging. Contains reviews by leading authorities in the respective areas Presents Up-to-date reviews of latest techniques in modeling of catalytic processes Includes a mix of US and European authors, as well as academic/industrial/research institute perspectives Contains the critical connections between computation and experimental methods

Download or read book Computational Granular Mechanics and Its Engineering Applications written by Shunying Ji and published by Springer Nature. This book was released on 2020-03-18 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book systematically introduces readers to computational granular mechanics and its relative engineering applications. Part I describes the fundamentals, such as the generation of irregular particle shapes, contact models, macro-micro theory, DEM-FEM coupling, and solid-fluid coupling of granular materials. It also discusses the theory behind various numerical methods developed in recent years. Further, it provides the GPU-based parallel algorithm to guide the programming of DEM and examines commercial and open-source codes and software for the analysis of granular materials. Part II focuses on engineering applications, including the latest advances in sea-ice engineering, railway ballast dynamics, and lunar landers. It also presents a rational method of parameter calibration and thorough analyses of DEM simulations, which illustrate the capabilities of DEM. The computational mechanics method for granular materials can be applied widely in various engineering fields, such as rock and soil mechanics, ocean engineering and chemical process engineering.

Download or read book Proceedings of China Europe Conference on Geotechnical Engineering written by Wei Wu and published by Springer. This book was released on 2018-08-02 with total page 881 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book compiles the first part of contributions to the China–Europe Conference on Geotechnical Engineering held 13.-16. August 2016 in Vienna, Austria. About 400 papers from 35 countries cover virtually all areas of geotechnical engineering and make this conference a truly international event. The contributions are grouped into thirteen special sessions and provide an overview of the geoengineering research and practice in China, Europe and the world: · Constitutive model · Micro-macro relationship · Numerical simulation · Laboratory testing · Geotechnical monitoring, instrumentation and field test · Foundation engineering · Underground construction · Environmental geotechnics · New geomaterials and ground improvement · Cold regions geotechnical engineering · Geohazards – risk assessment, mitigation and prevention · Unsaturated soils and energy geotechnics · Geotechnics in transportation, structural and hydraulic Engineering

Download or read book Geomechanics from Micro to Macro written by Kenichi Soga and published by CRC Press. This book was released on 2014-08-26 with total page 1668 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geomechanics from Micro to Macro contains 268 papers presented at the International Symposium on Geomechanics from Micro and Macro (IS-Cambridge, UK, 1-3 September 2014). The symposium created a forum for the dissemination of new advances in the micro-macro relations of geomaterial behaviour and its modelling. The papers on experimental investigati

Download or read book Proceedings of GeoShanghai 2018 International Conference Fundamentals of Soil Behaviours written by Annan Zhou and published by Springer. This book was released on 2018-05-10 with total page 1008 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the second volume of the proceedings of the 4th GeoShanghai International Conference that was held on May 27 - 30, 2018. The book, entitled “Fundamentals of Soil Behaviours”, presents the recent advances and technology in the understanding and modelling of fundamentals of soil’s behaviours. The subject of this book covers a wide range of topics related to soil behaviours in geotechnical engineering, geoenvironmental engineering and transportation engineering. The state-of-the-art theories, methodologies and findings in the related topics are included. This book may benefit researchers and scientists from the academic fields of soil and rock mechanics, geotechnical engineering, geoenvironmental engineering, transportation engineering, geology, mining and energy, as well as practical engineers from industry. Each of the papers included in this book received at least two positive peer reviews. The editors would like to express their sincerest appreciation to all of the anonymous reviewers all over the world, for their diligent work.

Download or read book Views on Microstructures in Granular Materials written by Pasquale Giovine and published by Springer Nature. This book was released on 2020-11-09 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This contributed volume provides an up-to-date overview of the mechanics of granular materials, ranging from sparse media to soils. With chapters exploring state-of-the-art theoretical, experimental, and applied trends in the study of granular matter in various states, readers will be motivated to learn about the current challenges and potential avenues of exploration in this active area of research. Including a variety of perspectives, this volume will be a valuable reference for audiences in a number of fields. Specific topics covered include: X-ray tomography techniques for analyzing sand Evaluation of effective stress in unsaturated soils Hyper-plasticity Wave propagation in granular systems Partly saturated porous media Multi-scale approaches to the dynamics of sparse media Views on Microstructures in Granular Materials is an ideal resource for PhD students and researchers in applied mathematics, solid-state physics, civil engineering, and mechanical engineering.

Download or read book Multiscale Geomechanics written by Pierre-Yves Hicher and published by John Wiley & Sons. This book was released on 2013-02-28 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the latest issues in multiscale geomechanics. Written by leading experts in the field as a tribute to Jean Biarez (1927-2006), it can be of great use and interest to researchers and engineers alike. A brief introduction describes how a major school of soil mechanics came into being through the exemplary teaching by one man. Biarez's life-long work consisted of explaining the elementary mechanisms governing soil constituents in order to enhance understanding of the underlying scientific laws which control the behavior of constructible sites and to incorporate these scientific advancements into engineering practices. He innovated a multiscale approach of passing from the discontinuous medium formed by individual grains to an equivalent continuous medium. The first part of the book examines the behavior of soils at the level of their different constituents and at the level of their interaction. Behavior is then treated at the scale of the soil sample. The second part deals with soil mechanics from the vantage point of the construction project. It highlights Biarez's insightful adoption of the Finite Element Codes and illustrates, through numerous construction examples, his methodology and approach based on the general framework he constructed for soil behavior, constantly enriched by comparing in situ measurements with calculated responses of geostructures.

Download or read book MESO SCALE SIMULATIONS OF COMPACTION WAVES IN A GRANULAR BED written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A granular bed provides an extreme example of a heterogeneous material. Behind a moderate strength wave, the shock compression in a granular material is due to squeezing out pore space rather than an increase in the density of individual grains. This type of shock is known as a compaction wave. The key properties of compaction waves are displayed in mesomechanics simulations--continuum mechanics calculations in which individual grains are resolved. Fluctuations in hydrodynamic quantities occur behind the wave front due to stress concentrations at the contact between grains exceeding the yield strength and leading to localized plastic flow. Nevertheless, average wave profiles have the appearance of a dispersed shock wave, and for the most part the fluid mechanics equations, with the addition of a porosity variable, can be used as a homogenized model to describe the behavior of a granular bed. However, some aspects of the wave structure are not accounted for by the homogenized model. These include dispersion of weak waves and an elastic precursor for intermediate strength waves.