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Special Issue "Granular Materials"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (30 June 2017)

Special Issue Editor

Guest Editor
Prof. Dr. Sinisa Dj. Mesarovic

School of Mechanical & Materials Engineering, Washington State University, PO Box 642920, Pullman, Washington 99164-2920, USA
Website | E-Mail
Interests: plasticity of crystals and interfaces; granular materials; coupled problems with moving boundaries; multiscale/multiphysics models

Special Issue Information

Dear Colleagues,

Almost two and a half centuries after Coulomb’s first investigations, granular materials still elude full understanding. The disorder in a granular assembly with apparent partial ordering (force chains, fabric), variety of particle shapes and size statistics, as well as the highly constrained kinematics of densely packed particles defy our attempts to formulate a predictive theory, capable of describing dilatancy, shear localization, flow patterns and transition from solid-like (jammed) state to fluid-like flow. Recent advances in experimental techniques and computing power enable more accurate observations and analysis of the particle-scale phenomena and their effects on the collective behaviour.

The problems in granular materials have engaged multiple scientific communities: Engineers, physicists and mathematicians. The Special Issue on “Granular Materials” is intended as a multi-disciplinary forum to present the current state-of-the-art and recent advances, as well as to suggest the future directions. Experimental, computational and theoretical contributions are invited. Of particular interest are the contributions, which provide understanding of micro-scale mechanisms and/or enable their description within meso-scale models.

The list of keywords given below provides brief summary of the open issues. The list is illustrative and the contributions are not limited to these topics.

Prof. Dr. Sinisa Dj. Mesarovic
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Dilatancy and Critical state
  • Force chains and Anisotropy
  • Particle kinematics and Collective behaviour
  • Jamming and flow of granular assemblies
  • Packing

Published Papers (8 papers)

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Research

Open AccessArticle Force Transmission Modes of Non-Cohesive and Cohesive Materials at the Critical State
Materials 2017, 10(9), 1014; doi:10.3390/ma10091014
Received: 15 July 2017 / Revised: 26 August 2017 / Accepted: 29 August 2017 / Published: 31 August 2017
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Abstract
This paper investigates the force transmission modes, mainly described by probability density distributions, in non-cohesive dry and cohesive wet granular materials by discrete element modeling. The critical state force transmission patterns are focused on with the contact model effect being analyzed. By shearing
[...] Read more.
This paper investigates the force transmission modes, mainly described by probability density distributions, in non-cohesive dry and cohesive wet granular materials by discrete element modeling. The critical state force transmission patterns are focused on with the contact model effect being analyzed. By shearing relatively dense and loose dry specimens to the critical state in the conventional triaxial loading path, it is observed that there is a unique critical state force transmission mode. There is a universe critical state force distribution pattern for both the normal contact forces and tangential contact forces. Furthermore, it is found that using either the linear Hooke or the non-linear Hertz model does not affect the universe force transmission mode, and it is only related to the grain size distribution. Wet granular materials are also simulated by incorporating a water bridge model. Dense and loose wet granular materials are tested, and the critical state behavior for the wet material is also observed. The critical state strength and void ratio of wet granular materials are higher than those of a non-cohesive material. The critical state inter-particle distribution is altered from that of a non-cohesive material with higher probability in relatively weak forces. Grains in non-cohesive materials are under compressive stresses, and their principal directions are mainly in the axial loading direction. However, for cohesive wet granular materials, some particles are in tension, and the tensile stresses are in the horizontal direction on which the confinement is applied. The additional confinement by the tensile stress explains the macro strength and dilatancy increase in wet samples. Full article
(This article belongs to the Special Issue Granular Materials)
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Open AccessArticle The Quantified Characterization Method of the Micro-Macro Contacts of Three-Dimensional Granular Materials on the Basis of Graph Theory
Materials 2017, 10(8), 898; doi:10.3390/ma10080898
Received: 22 May 2017 / Revised: 21 July 2017 / Accepted: 25 July 2017 / Published: 3 August 2017
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Abstract
We have attempted a multiscale and quantified characterization method of the contact in three-dimensional granular material made of spherical particles, particularly in cemented granular material. Particle contact is defined as a type of surface contact with voids in its surroundings, rather than a
[...] Read more.
We have attempted a multiscale and quantified characterization method of the contact in three-dimensional granular material made of spherical particles, particularly in cemented granular material. Particle contact is defined as a type of surface contact with voids in its surroundings, rather than a point contact. Macro contact is a particle contact set satisfying the restrictive condition of a two-dimensional manifold with a boundary. On the basis of graph theory, two dual geometrical systems are abstracted from the granular pack. The face and the face set, which satisfies the two-dimensional manifold with a boundary in the solid cell system, are extracted to characterize the particle contact and the macro contact, respectively. This characterization method is utilized to improve the post-processing in DEM (Discrete Element Method) from a micro perspective to describe the macro effect of the cemented granular material made of spherical particles. Since the crack has the same shape as its corresponding contact, this method is adopted to characterize the crack and realize its visualization. The integral failure route of the sample can be determined by a graph theory algorithm. The contact force is assigned to the weight value of the face characterizing the particle contact. Since the force vectors can be added, the macro contact force can be solved by adding the weight of its corresponding faces. Full article
(This article belongs to the Special Issue Granular Materials)
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Open AccessArticle Impact Load Behavior between Different Charge and Lifter in a Laboratory-Scale Mill
Materials 2017, 10(8), 882; doi:10.3390/ma10080882
Received: 28 June 2017 / Revised: 16 July 2017 / Accepted: 29 July 2017 / Published: 31 July 2017
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Abstract
The impact behavior between the charge and lifter has significant effect to address the mill processing, and is affected by various factors including mill speed, mill filling, lifter height and media shape. To investigate the multi-body impact load behavior, a series of experiments
[...] Read more.
The impact behavior between the charge and lifter has significant effect to address the mill processing, and is affected by various factors including mill speed, mill filling, lifter height and media shape. To investigate the multi-body impact load behavior, a series of experiments and Discrete Element Method (DEM) simulations were performed on a laboratory-scale mill, in order to improve the grinding efficiency and prolong the life of the lifter. DEM simulation hitherto has been extensively applied as a leading tool to describe diverse issues in granular processes. The research results shown as follows: The semi-empirical power draw of Bond model in this paper does not apply very satisfactorily for the ball mills, while the power draw determined by DEM simulation show a good approximation for the measured power draw. Besides, the impact force on the lifter was affected by mill speed, grinding media filling, lifter height and iron ore particle. The maximum percent of the impact force between 600 and 1400 N is at 70–80% of critical speed. The impact force can be only above 1400 N at the grinding media filling of 20%, and the maximum percent of impact force between 200 and 1400 N is obtained at the grinding media filling of 20%. The percent of impact force ranging from 0 to 200 N decreases with the increase of lifter height. However, this perfect will increase above 200 N. The impact force will decrease when the iron ore particles are added. Additionally, for the 80% of critical speed, the measured power draw has a maximum value. Increasing the grinding media filling increases the power draw and increasing the lifter height does not lead to any variation in power draw. Full article
(This article belongs to the Special Issue Granular Materials)
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Open AccessArticle On Critical States, Rupture States and Interlocking Strength of Granular Materials
Materials 2017, 10(8), 865; doi:10.3390/ma10080865
Received: 30 June 2017 / Revised: 19 July 2017 / Accepted: 21 July 2017 / Published: 27 July 2017
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Abstract
The Mohr-Coulomb theory of strength identifies cohesion and internal friction as the two principal contributions to the shear strength of a granular material. The contribution of cohesion in over-compacted granular materials has been challenged and replacing cohesion with interlocking has been proposed. A
[...] Read more.
The Mohr-Coulomb theory of strength identifies cohesion and internal friction as the two principal contributions to the shear strength of a granular material. The contribution of cohesion in over-compacted granular materials has been challenged and replacing cohesion with interlocking has been proposed. A theory of rupture strength that includes interlocking is derived herein. The physics-chemistry concept of critical state is elaborated to accommodate granular materials, based on empirical definitions established in the fields of soil mechanics and bulk solids’ flow. A surface in state space, called the critical compaction surface, separates over-compacted states from lightly compacted states. The intersection of this surface with the Mohr-Coulomb envelope forms the critical state surface for a granular material. The rupture strength of an over-compacted granular material is expressed as the sum of cohesion, internal friction and interlocking strength. Interlocking strength is the shear strength contribution due to over-compaction and vanishes at critical state. The theory allows migrations from one critical state to another. Changes in specific volume during such migrations are related to changes in mean-normal effective stress and uncoupled from changes in shearing strain. The theory is reviewed with respect to two established research programs and underlying assumptions are identified. Full article
(This article belongs to the Special Issue Granular Materials)
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Open AccessArticle The Use of Empirical Methods for Testing Granular Materials in Analogue Modelling
Materials 2017, 10(6), 635; doi:10.3390/ma10060635
Received: 14 April 2017 / Revised: 18 May 2017 / Accepted: 5 June 2017 / Published: 9 June 2017
Cited by 1 | PDF Full-text (10012 KB) | HTML Full-text | XML Full-text
Abstract
The behaviour of a granular material is mainly dependent on its frictional properties, angle of internal friction, and cohesion, which, together with material density, are the key factors to be considered during the scaling procedure of analogue models. The frictional properties of a
[...] Read more.
The behaviour of a granular material is mainly dependent on its frictional properties, angle of internal friction, and cohesion, which, together with material density, are the key factors to be considered during the scaling procedure of analogue models. The frictional properties of a granular material are usually investigated by means of technical instruments such as a Hubbert-type apparatus and ring shear testers, which allow for investigating the response of the tested material to a wide range of applied stresses. Here we explore the possibility to determine material properties by means of different empirical methods applied to mixtures of quartz and K-feldspar sand. Empirical methods exhibit the great advantage of measuring the properties of a certain analogue material under the experimental conditions, which are strongly sensitive to the handling techniques. Finally, the results obtained from the empirical methods have been compared with ring shear tests carried out on the same materials, which show a satisfactory agreement with those determined empirically. Full article
(This article belongs to the Special Issue Granular Materials)
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Open AccessArticle The Stability Analysis Method of the Cohesive Granular Slope on the Basis of Graph Theory
Materials 2017, 10(3), 240; doi:10.3390/ma10030240
Received: 25 November 2016 / Accepted: 17 February 2017 / Published: 27 February 2017
Cited by 1 | PDF Full-text (3674 KB) | HTML Full-text | XML Full-text
Abstract
This paper attempted to provide a method to calculate progressive failure of the cohesivefrictional granular geomaterial and the spatial distribution of the stability of the cohesive granular slope. The methodology can be divided into two parts: the characterization method of macro-contact and the
[...] Read more.
This paper attempted to provide a method to calculate progressive failure of the cohesivefrictional granular geomaterial and the spatial distribution of the stability of the cohesive granular slope. The methodology can be divided into two parts: the characterization method of macro-contact and the analysis of the slope stability. Based on the graph theory, the vertexes, the edges and the edge sequences are abstracted out to characterize the voids, the particle contact and the macro-contact, respectively, bridging the gap between the mesoscopic and macro scales of granular materials. This paper adopts this characterization method to extract a graph from a granular slope and characterize the macro sliding surface, then the weighted graph is analyzed to calculate the slope safety factor. Each edge has three weights representing the sliding moment, the anti-sliding moment and the braking index of contact-bond, respectively, . The safety factor of the slope is calculated by presupposing a certain number of sliding routes and reducing Weight repeatedly and counting the mesoscopic failure of the edge. It is a kind of slope analysis method from mesoscopic perspective so it can present more detail of the mesoscopic property of the granular slope. In the respect of macro scale, the spatial distribution of the stability of the granular slope is in agreement with the theoretical solution. Full article
(This article belongs to the Special Issue Granular Materials)
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Open AccessArticle Numerical Simulation on Seismic Response of the Filled Joint under High Amplitude Stress Waves Using Finite-Discrete Element Method (FDEM)
Materials 2017, 10(1), 13; doi:10.3390/ma10010013
Received: 31 October 2016 / Revised: 16 December 2016 / Accepted: 18 December 2016 / Published: 27 December 2016
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Abstract
This paper numerically investigates the seismic response of the filled joint under high amplitude stress waves using the combined finite-discrete element method (FDEM). A thin layer of independent polygonal particles are used to simulate the joint fillings. Each particle is meshed using the
[...] Read more.
This paper numerically investigates the seismic response of the filled joint under high amplitude stress waves using the combined finite-discrete element method (FDEM). A thin layer of independent polygonal particles are used to simulate the joint fillings. Each particle is meshed using the Delaunay triangulation scheme and can be crushed when the load exceeds its strength. The propagation of the 1D longitude wave through a single filled joint is studied, considering the influences of the joint thickness and the characteristics of the incident wave, such as the amplitude and frequency. The results show that the filled particles under high amplitude stress waves mainly experience three deformation stages: (i) initial compaction stage; (ii) crushing stage; and (iii) crushing and compaction stage. In the initial compaction stage and crushing and compaction stage, compaction dominates the mechanical behavior of the joint, and the particle area distribution curve varies little. In these stages, the transmission coefficient increases with the increase of the amplitude, i.e., peak particle velocity (PPV), of the incident wave. On the other hand, in the crushing stage, particle crushing plays the dominant role. The particle size distribution curve changes abruptly with the PPV due to the fragments created by the crushing process. This process consumes part of wave energy and reduces the stiffness of the filled joint. The transmission coefficient decreases with increasing PPV in this stage because of the increased amount of energy consumed by crushing. Moreover, with the increase of the frequency of the incident wave, the transmission coefficient decreases and fewer particles can be crushed. Under the same incident wave, the transmission coefficient decreases when the filled thickness increases and the filled particles become more difficult to be crushed. Full article
(This article belongs to the Special Issue Granular Materials)
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Open AccessArticle An Experimental Study of Mortars with Recycled Ceramic Aggregates: Deduction and Prediction of the Stress-Strain
Materials 2016, 9(12), 1029; doi:10.3390/ma9121029
Received: 18 October 2016 / Revised: 28 November 2016 / Accepted: 13 December 2016 / Published: 21 December 2016
Cited by 1 | PDF Full-text (7617 KB) | HTML Full-text | XML Full-text
Abstract
The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the
[...] Read more.
The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε); therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%), such as the density and compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content) are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications. Full article
(This article belongs to the Special Issue Granular Materials)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Evidence of metastable attractors in dense granular materials
Author: Sebastian Pucilowski, Antoinette Tordesillas, Gary Froyland
Abstract: We study the metastable dynamics of dense granular systems deforming in the presence of persistent shear bands in two- and three-dimensions from the perspective of its conformational landscape: the state space formed by all observed grain conformations, as defined by the local mesoscale topology of grains relative to their first ring of contacting neighbours. Peaks in the distributions of grain conformations reveal preferred self-assembled mesostructures. The conformational landscape is partitioned into metastable almost-invariant regions or sets, such that grain rearrangements from one conformation to another in the same almost-invariant set occurs with high probability, and rearrangements between almost-invariant sets are unlikely. The great majority of conformational transitions are identity transitions: grains rearrange and exchange contacts to preserve those topological properties with the greatest influence on cluster stability, namely, the number of contacts and 3-cycles. Dynamical transition barriers are observed in which non-identity conformational transitions are favoured or impeded. Force chains show a clear preference for almost-invariant sets with the most number of accessible and highly connected conformations, with rearrangements preserving structural stability. These metastable regions make ideal breeding grounds for future force chains. When force chains become overloaded and fail by buckling in the shear zone, the energy released enables member grains to overcome the dynamical barriers that seperate metastable regions and enable a transition to another in the conformational landscape.
These buckling force chain grains, compared to grains locked in stable force chains, show preference for not only non-identity transitions within each metastable region but also transitions between metastable regions.

Title: Basic features of the quasi-static mechanical behavior of model granular materials studied by discrete numerical simulations.
Authors: Jean-Noël Roux, Chloë Dequeker

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