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 A Multi scale Approach to a Greater Understanding of the Behavior of Heterogeneous Materials Under Dynamic Loading written by Andrew J. Van Vooren and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The penetration of granular materials is of interest to a variety of different fields, and is an active area of research. The objective of this project is to gain understanding of the dynamics of a projectile penetrating into a granular material. To do this, experiments were run and a numerical model was created. A dart gun was used to accelerate an aluminum dart to velocities around 100 m/s, which then impacted a target tank filled with Ottawa sand. The dart flew along a view window, which allowed for a recording of the penetration event using a high speed camera. Pressure gauges inserted into the target tank measured the timing and magnitude of the compaction wave created by the dart. In these penetration events a two wave structure was discovered; a compaction wave and a fracture wave. The fracture wave is characterized by a white cone around the nose of the dart, which is created by increased reflectance from the newly created fracture surfaces in the grains of sand. An experiment was conducted in which single grain of sand was crushed. From this experiment it was discovered that the phenomenon that creates increased reflectivity is the creation of fractures faces in the sand, and is not triboluminescence. Stress-strain data for the sand was also gathered, to be used in the numerical simulation. An ultrasonic pulser/receiver was used to gather data on the longitudinal and shear wave sound speeds through "as poured" Ottawa sand; 263 m/s and 209 m/s respectively. It was determined that the compaction and damage wave speeds were not related to either the longitudinal or shear wave speeds. A numerical model was created using an EMU Peridynamic code. This code utilizes integral rather than differential equations, which allows for the modeling of crack propagation and fracture. The numerical simulations run were two-dimensional and on a smaller scale than the penetration experiments. The numerical simulation showed evidence of a compaction wave, force chain creation, and grain fracture, all of which were also observed in the penetration experiments.

Download or read book Understanding the Discrete Element Method written by Hans-Georg Matuttis and published by John Wiley & Sons. This book was released on 2014-06-23 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gives readers a more thorough understanding of DEM and equips researchers for independent work and an ability to judge methods related to simulation of polygonal particles Introduces DEM from the fundamental concepts (theoretical mechanics and solidstate physics), with 2D and 3D simulation methods for polygonal particles Provides the fundamentals of coding discrete element method (DEM) requiring little advance knowledge of granular matter or numerical simulation Highlights the numerical tricks and pitfalls that are usually only realized after years of experience, with relevant simple experiments as applications Presents a logical approach starting withthe mechanical and physical bases,followed by a description of the techniques and finally their applications Written by a key author presenting ideas on how to model the dynamics of angular particles using polygons and polyhedral Accompanying website includes MATLAB-Programs providing the simulation code for two-dimensional polygons Recommended for researchers and graduate students who deal with particle models in areas such as fluid dynamics, multi-body engineering, finite-element methods, the geosciences, and multi-scale physics.

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 The Cell Method written by Elena Ferretti and published by Momentum Press. This book was released on 2014-02-02 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cell Method (CM) is a computational tool that maintains critical multidimensional attributes of physical phenomena in analysis. This information is neglected in the differential formulations of the classical approaches of finite element, boundary element, finite volume, and finite difference analysis, often leading to numerical instabilities and spurious results. This book highlights the central theoretical concepts of the CM that preserve a more accurate and precise representation of the geometric and topological features of variables for practical problem solving. Important applications occur in fields such as electromagnetics, electrodynamics, solid mechanics and fluids. CM addresses non-locality in continuum mechanics, an especially important circumstance in modeling heterogeneous materials. Professional engineers and scientists, as well as graduate students, are offered: • A general overview of physics and its mathematical descriptions; • Guidance on how to build direct, discrete formulations; • Coverage of the governing equations of the CM, including nonlocality; • Explanations of the use of Tonti diagrams; and • References for further reading.

Download or read book Behaviour of Granular Materials written by Bernard Cambou and published by Springer Science & Business Media. This book was released on 1998-08-12 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a complete and comprehensive analysis of the behaviour of granular materials including the description of experimental results, the different ways to define the global behaviour from local phenomena at the particle scale, the various modellings which can be used for a D.E.M. analysis to solve practical problems and finally the analysis of strain localisation. The concepts developed in this book are applicable to many kinds of granular materials considered in civil, mechanical or chemical engineering.

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 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 A Network cell Based Framework for Multiscale Analysis of Granular Materials written by Jagan Mohan Padbidri and published by . This book was released on 2010 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Discrete Element Method to Model 3D Continuous Materials written by Mohamed Jebahi and published by John Wiley & Sons. This book was released on 2015-03-30 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex behavior models (plasticity, cracks, visco elascticity) face some theoretical difficulties for the determination of the behavior law at the continuous scale. When homogenization fails to give the right behavior law, a solution is to simulate the material at a meso scale in order to simulate directly a set of discrete properties that are responsible of the macroscopic behavior. The discrete element model has been developed for granular material. The proposed set shows how this method is capable to solve the problem of complex behavior that are linked to discrete meso scale effects.

Download or read book Multi Scale Modeling and Characterization of Infrastructure Materials written by Niki Kringos and published by Springer Science & Business Media. This book was released on 2013-05-26 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: The micro- and nano-modification of infrastructure materials and the associated multi-scale characterization and simulation has the potential to open up whole new uses and classes of materials, with wide-ranging implications for society. The use of multi-scale characterization and simulation brings the ability to target changes at the very small scale that predictably effect the bulk behavior of the material and thus allowing for the optimization of material behavior and performance. The International RILEM Symposium on Multi-Scale Modeling and Characterization of Infrastructure Materials (Stockholm, June 10-12, 2013) brought together key researchers from around the world to present their findings and ongoing research in this field in a focused environment with extended discussion times. From asphalt to concrete, from chemistry to mechanics, from nano- to macro-scale: the collection of topics covered by the Symposium represents the width and depth of the currently ongoing efforts of developing more sustainable infrastructure materials. Researchers, practitioners, undergraduates and graduate students engaged in infrastructure materials or multi-scale characterization and modeling efforts can use this book as a comprehensive reference, to learn about the currently ongoing research efforts in this field or as an inspiration for new research ideas to enhance the long-term performance of infrastructure materials from a fundamental perspective. The Symposium was held under the auspices of the RILEM Technical Committee on Nanotechnology-Based Bituminous Materials 231-NBM and the Transport Research Board (TRB) Technical Committee on Characteristics of Asphalt Materials AFK20.

Download or read book The Material Point Method for Geotechnical Engineering written by James Fern and published by CRC Press. This book was released on 2019-01-30 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: This practical guide provides the best introduction to large deformation material point method (MPM) simulations for geotechnical engineering. It provides the basic theory, discusses the different numerical features used in large deformation simulations, and presents a number of applications -- providing references, examples and guidance when using MPM for practical applications. MPM covers problems in static and dynamic situations within a common framework. It also opens new frontiers in geotechnical modelling and numerical analysis. It represents a powerful tool for exploring large deformation behaviours of soils, structures and fluids, and their interactions, such as internal and external erosion, and post-liquefaction analysis; for instance the post-failure liquid-like behaviours of landslides, penetration problems such as CPT and pile installation, and scouring problems related to underwater pipelines. In the recent years, MPM has developed enough for its practical use in industry, apart from the increasing interest in the academic world.

Download or read book Multi physics Modeling and Simulations of Thermally assisted Compaction of Granular Materials written by Gülşad Küçük and published by . This book was released on 2015 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Having characteristics that differ from those associated with solids, liquids, and gases, granu- lar materials require miscellaneous multi-physics approaches that integrate theories at different scales. The abstract behavior of granular material provides limitless arrangements in terms of microscopic and macroscopic properties, specifically concerning the thermally-assisted com- paction process. However the uniqueness of particulate systems reduces significantly the effec- tiveness of conventional compaction models based on continuum mechanics description. Thus the current study engages with the problem at both discrete and continuum levels, and bridges the gap between particle-mechanics and macro-scale theories. A mathematical formulation that integrates the thermal and mechanical behavior of discrete system of particles is presented. It is worth noting that thermal expansion experienced by the compacted particles increases the nonlinearity in the thermo-elastic contact problem, which results in various interesting aspects unique to granular matter. Numerical analysis reveals the role of thermal expansion, the role applied thermal and mechanical loads during thermally- assisted compaction of spherical, perfectly conforming particles. Modeling consolidated granular media by using continuum mechanics requires an addi- tional concentration on defining the effective transport properties of the material. Taking advantage of the effective medium approximation, an equivalent continuum model for the state of small-strain deformation under the applied thermal gradient is investigated. The discrepancy between discrete and continuum analysis underlines the importance of describing an effective thermal expansion parameter. Starting from the fundamental understanding of particle interac- tions, an effective thermal expansion coefficient is derived for the current problem statement. Unlike the continuum media, granular materials host inhomogeneous distribution of con- tact networks, which results in uneven distribution of loads in the dense particulate assemblies. Moreover these structural arrangements play critical role in forming preferred paths of heat transport. In spite of the recent experimental and theoretical studies on the evolution of force chains, the formation of heat chains and the correlation between the heat and force chains still remain unclear. In this study two-dimensional numerical simulations are demonstrated to un- derstand some of the fundamental concepts such as: (i) formation of force and heat chains (ii) formation of localized hot zones, (iii) cross-property relations between contact force distribu- tions and heat transported at the contact surfaces, (iv) influence of system characteristics such as diverse size distribution of particles, binary material constituents and different boundary conditions.

Download or read book 3D Kinematic and Strength Behavior of Granular Materials at the Particle level written by Mehmet Burak Cil and published by . This book was released on 2015 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: The macro-scale behavior of uncemented granular materials is governed by the particle-to-particle interactions. Therefore, accurate assessment of the micro-scale mechanics is essential for better understanding of the fundamental behavior of granular materials. Particle fracture phenomenon and force transmission mechanisms in natural granular assemblies such as sands have not been fully understood due to the lack of micro-scale experimental measurements. The objective of this dissertation is to provide key quantitative measurements about these issues using powerful non-destructive experimental 3D x-ray diffraction (3DXRD) and synchrotron micro-tomography (SMT) techniques, as well as distinct element method (DEM). 3DXRD was employed to measure the volume-averaged lattice strain of individual silica sand particles within a sand assembly under 1D compression loading condition. The evolution and distribution of particle fracture, particle fracture mechanism and deformation characteristics of sand particles subjected to 1D compression across the scales were also investigated and quantified using SMT and DEM methods. Sand particles were modeled in DEM as crushable agglomerates composed of many spherical sub-particles that were linked by parallel bonds. DEM simulations were first calibrated and validated using laboratory experiments, and then were used to quantify micro-scale processes including the contact force network, and the fracture mechanics of crushable agglomerates. In addition, DEM was adopted to examine particle kinematic behavior and the influence of boundary conditions in triaxial testing. In first set of lattice strain measurements performed on a column composed of three sand particles, the normal strain along the loading direction increased in a linear fashion as the compression proceeded until one of the sand particle fractured. However, significant variation and fluctuations were observed in the measured lattice strain tensor components of sand particles for relatively larger specimen due to complex deformation behavior and a non-homogenous contact force network. The SMT images and DEM model revealed that particle fracture concentrates at certain locations close to the loading platen, and the onset of particle fracture and specimen yielding occur at the same strain level in a 1D compression test. Finally, triaxial test DEM simulations showed that a flexible membrane better replicates the uniformly applied confining stress compared to a rigid boundary.

Download or read book Uncertainty Quantification in Multiscale Materials Modeling written by Yan Wang and published by Woodhead Publishing Limited. This book was released on 2020-03-12 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt: Uncertainty Quantification in Multiscale Materials Modeling provides a complete overview of uncertainty quantification (UQ) in computational materials science. It provides practical tools and methods along with examples of their application to problems in materials modeling. UQ methods are applied to various multiscale models ranging from the nanoscale to macroscale. This book presents a thorough synthesis of the state-of-the-art in UQ methods for materials modeling, including Bayesian inference, surrogate modeling, random fields, interval analysis, and sensitivity analysis, providing insight into the unique characteristics of models framed at each scale, as well as common issues in modeling across scales.

Download or read book Structural Analysis of Historical Constructions Anamnesis Diagnosis Therapy Controls written by Koen Van Balen and published by CRC Press. This book was released on 2016-11-03 with total page 1879 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural Analysis of Historical Constructions. Anamnesis, diagnosis, therapy, controls contains the papers presented at the 10th International Conference on Structural Analysis of Historical Constructions (SAHC2016, Leuven, Belgium, 13-15 September 2016). The main theme of the book is “Anamnesis, Diagnosis, Therapy, Controls”, which emphasizes the importance of all steps of a restoration process in order to obtain a thorough understanding of the structural behaviour of built cultural heritage. The contributions cover every aspect of the structural analysis of historical constructions, such as material characterization, structural modelling, static and dynamic monitoring, non-destructive techniques for on-site investigation, seismic behaviour, rehabilitation, traditional and innovative repair techniques, and case studies. The knowledge, insights and ideas in Structural Analysis of Historical Constructions. Anamnesis, diagnosis, therapy, controls make this book of abstracts and the corresponding, digital full-colour conference proceedings containing the full papers must-have literature for researchers and practitioners involved in the structural analysis of historical constructions.

Download or read book Multiscale Modeling in Granular Flow written by Christopher Harley Rycroft and published by . This book was released on 2007 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: Granular materials are common in everyday experience, but have long-resisted a complete theoretical description. Here, we consider the regime of slow, dense granular flow, for which there is no general model, representing a considerable hurdle to industry, where grains and powders must frequently be manipulated. Much of the complexity of modeling granular materials stems from the discreteness of the constituent particles, and a key theme of this work has been the connection of the microscopic particle motion to a bulk continuum description. This led to development of the "spot model", which provides a microscopic mechanism for particle rearrangement in dense granular flow, by breaking down the motion into correlated group displacements on a mesoscopic length scale. The spot model can be used as the basis of a multiscale simulation technique which can accurately reproduce the flow in a large-scale discrete element simulation of granular drainage, at a fraction of the computational cost. In addition, the simulation can also successfully track microscopic packing signatures, making it one of the first models of a flowing random packing. To extend to situations other than drainage ultimately requires a treatment of material properties, such as stress and strain-rate, but these quantities are difficult to define in a granular packing, due to strong heterogeneities at the level of a single particle. However, they can be successfully interpreted at the mesoscopic spot scale, and this information can be used to directly test some commonly-used hypotheses in modeling granular materials, providing insight into formulating a general theory.