Showing papers on "Breakage published in 2016"
TL;DR: In this article, the influence of particle breakage on the position of the critical state line (CSL) was systematically investigated through a series of large-scale triaxial compression tests on Tacheng rockfill material (TRM).
Abstract: The influences of particle breakage on the position of the critical state line (CSL) were systematically investigated in this paper through a series of large-scale triaxial compression tests on Tacheng rockfill material (TRM). It was found that the critical-state stress ratio of TRM (i.e., the gradient of the CSL in the p−q space) was approximately regarded as a constant. In the e−logp space, the CSL of TRM descended with a decrease in the initial void ratio, whereas the gradient of the CSL was constant. A procedure was established for evaluating the critical state point at a same particle breakage, which comprised the breakage critical state line (BCSL). An increase of the particle breakage led to not only a vertical translation but also a rotation on the BCSL of TRM in the e−logp space, which was similar to the observation of Dog’s Bay sand. Consequently, the initial gradation (or the corresponding initial void ratio) was the dominant factor that affected the position of the CSL of TRM in the e−...
205 citations
TL;DR: In this article, a series of single particle uniaxial compression tests on different kinds of sand particles were carried out, using a high-speed microscope camera to capture the processes of breakage.
Abstract: Much research has focused on the micro-mechanics of sand particles. The single particle uniaxial compression test is a common way to study breakage behaviour. However, there is still little agreement on particle breakage criteria and the mechanisms of breakage remain uncertain, partly because of the often rapid brittle failure of sand particles. In this study, a series of single particle uniaxial compression tests on different kinds of sand particles were carried out, using a high-speed microscope camera to capture the processes of breakage. This enabled a maximum of 2000 frames to be obtained per second to identify clearly the failure processes and crack propagation. Four failure modes have been proposed based on the rapidity of failure and the size and number of particle fragments created during the breakage: splitting, explosive, explosive–splitting and chipping. The relationship between the particle strength and the breakage mode has then been explored, investigating also whether immersion would affec...
183 citations
TL;DR: In this article, the Kapur function analysis of stable and transient cavitation bubbles was used to investigate the breaking mechanism of paracetamol particles exposed to implosions of stable or transient bubbles.
Abstract: This paper investigates, for the first time, the breaking mechanism of particles exposed to implosions of stable and transient cavitation bubbles via Kapur function analysis. The effect of ultrasonic frequencies of 30–1140 kHz and powers of 4–200 W on particle breakage of paracetamol crystals was studied. The dominant cavitation bubble type was defined via sonoluminescence measurements. The breakage rate of seed crystals with a median size of 75 μm was found to be independent of the applied power when ultrasonically generated stable cavitation bubbles were generated. Furthermore, a particle size threshold of ca. 35 μm was observed. The particle size could not be reduced below this size regardless of the applied power or frequency. For transient bubbles, in contrast, higher powers lead to considerably smaller particles, with no threshold size within the investigated power range. The Kapur function analysis suggests that stable bubbles are more efficient than transient bubbles to break coarse particles with...
103 citations
TL;DR: In this paper, a series of cyclic drained triaxial tests was conducted on ballast with different sizes using the large-scale cylindrical tripleaxial apparatus designed and built at the University of Wollongong.
Abstract: The deformation and degradation of ballast is influenced by the size of the aggregates. In this study, a series of cyclic drained triaxial tests was conducted on ballast with different sizes using the large-scale cylindrical triaxial apparatus designed and built at the University of Wollongong, and two different frequencies of cyclic loading were used to simulate low-speed and high-speed trains. From the laboratory results, coarse particles experience less vertical and lateral strains, whereas the volumetric strains decrease and then increase as the coefficient of uniformity increases, regardless of the loading frequency. Resistance to deformation and degradation is found to be improved by increasing ballast density. Different trends between the extent of breakage and particle size are observed for different breakage indices, and accordingly the extent of breakage is characterized into two distinct zones, depending on the coefficient of uniformity (Cu), where the significantly reduced breakage cor...
89 citations
TL;DR: In this article, a three dimensional fracture model is presented in the context of combined finite-discrete element method (FDEM) to simulate the breakage of irregular shaped granular materials, e.g., sands, gravels, and rockfills.
Abstract: It is well known that particle breakage plays a critical role in the mechanical behavior of granular materials and has been a topic subject to intensive studies. This paper presents a three dimensional fracture model in the context of combined finite-discrete element method (FDEM) to simulate the breakage of irregular shaped granular materials, e.g., sands, gravels, and rockfills. In this method, each particle is discretized into a finite element mesh. The potential fracture paths are represented by pre-inserted non-thickness cohesive interface elements with a progressive damage model. The Mohr–Coulomb model with tension cut-off is employed as the damage initiation criterion to rupture the predominant failure mode at the particle scale. The particle breakage modeling using combined FDEM is validated by the qualitative agreement between the results of simulated single particle crushing tests and those obtained from laboratory tests and prior DEM simulations. A comprehensive numerical triaxial tests are carried out on both the unbreakable and breakable particle assemblies with varied confining pressure and particle crushability. The simulated stress–strain–dilation responses of breakable granular assembly are qualitatively in good agreement with the experimental observations. The effects of particle breakage on the compressibility, shear strength, volumetric response of the fairly dense breakable granular assembly are thoroughly investigated through a variety of mechanism demonstrations and micromechanical analysis. This paper also reports the energy input and dissipation behavior and its relation to the mechanical response.
77 citations
TL;DR: In this paper, the influence of joint spacing on the performance of TBM cutters was investigated for the Beishan granite samples with different joint spacing (i.e., one intact sample, two jointed samples with joint spacing of 100mm and 400mm).
75 citations
TL;DR: In this paper, a simple but comprehensive cyclic stress-strain model that incorporates particle breakage for granular soils including ballast and rockfill has been proposed on the basis of bounding boxes.
Abstract: In this paper, a simple but comprehensive cyclic stress–strain model that incorporates particle breakage for granular soils including ballast and rockfill has been proposed on the basis of bounding...
73 citations
TL;DR: In this article, a simulation of droplet breakage in turbulent liquid-liquid dispersions is simulated by using computational fluid dynamics and population balance modeling, validated against experimental data for eight test cases, namely stirred tanks with different geometries and different continuous and disperse phases.
73 citations
TL;DR: In this article, a random virtual crack DEM model is proposed for creep behavior of rockfill in PFC2D according to the theory of subcritical crack propagation induced by stress corrosion mechanisms.
Abstract: The post-construction settlement of rockfill dams and high filled ground of airport, which is a phenomenon of much significance, is mainly caused by the time-dependent breakage of the rockfill material. In this paper, a random virtual crack DEM model is proposed for creep behavior of rockfill in PFC2D according to the theory of subcritical crack propagation induced by stress corrosion mechanisms. The bonded clusters are adopted to represent the rockfill particles so as to simulate their irregular shapes. Virtual cracks are set at the bonds of the clusters, and the length of the crack is considered as a random value, which leads the crushing strength of a single particle to follow the Weibull’s statistical model and the corresponding size rules. Oedometric creep tests for rockfill are simulated by using this proposed model. The results show that the model, validated preliminarily by some test data, can reflect qualitatively the creep mechanism as well as the size effects reasonably. Particles can develop various breakage patterns during creep, including global breakage, local breakage and even complex mixed breakage. The increase in stress levels and particle size will lead to an obvious growth of the creep strain and creep rate of the rockfill. The scale effects on the creep behavior of rockfill are analyzed through 35 specimens, and formulas including the effects of scales and stress levels are tentatively proposed.
55 citations
TL;DR: The phase evolution and microstructure of the ceramic proppants sintered at different temperatures were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) as discussed by the authors.
52 citations
TL;DR: In this article, the authors present a review of 20 applications of the JK size-dependent breakage model for the mineral and coal industries in the past 10 years to encourage its use in future applications, including single impact data reduction, low energy incremental breakage modelling, reduced breakage testing method, and fine particle breakage characterisation (JKFBC).
TL;DR: In this article, the results of a high-speed imaging of a single stirrer blade were investigated by high speed imaging, and the results were presented with and without the addition of SDS to the continuous water phase.
TL;DR: In this paper, a Discrete Element Method (DEM) model is developed to study the particle breakage effect on the one-dimensional compression behavior of silica sands considering multiple contacts.
TL;DR: In this article, Zhao et al. presented particle breakage and the mobilized drained shear strengths of sand with the purpose of clarifying the influence of particles breakage on the mobilized shear strength of sand.
Abstract: This paper presents particle breakage and the mobilized drained shear strengths of sand with the purpose of clarifying the influence of particle breakage on the mobilized shear strengths of sand. Several drained triaxial tests were carried out on Silica sand No.5 under 3 MPa confining pressure to produce the pre-crushed sands in simulating the high-pressure shear process on soil to result in particle breakage, and then the pre-crushed sands were re-sheared in series of drained triaxial tests to investigate the mobilized strengths of the pre-crushed sands in detecting the influence of particle breakage. It was found that, by deteriorating strain-stress behavior, particle breakage resulted in change of stress-dilatancy behavior in translation and rotation of the relation of the dilatancy factor and the effective principal stress ratio. For a given initial void ratio, particle breakage resulted in impairment of dilatancy behavior of soil to be more contractive in deterioration of the mobilized friction angle and the mobilized dilatancy angle and reduction of void ratio. However, particle breakage resulted in increase of the mobilized basic friction angle especially before failure. In addition, the influence of particle breakage on the mobilized strengths was revealed to be influenced by the shear stress-strain state.
TL;DR: In this paper, a three-dimensional analytical helical gear pair model is developed by considering the mass eccentric and mesh stiffness induced by tooth breakage with sliding friction, which shows that the amplitude modulation phenomenon emerged in the dynamic transmission error of helical gears with tooth breakages.
TL;DR: In this article, the authors proposed a model to describe a single breakage event by modelling it as a process through several stages of primary fracture while appreciating the effect of sequential fragmentation.
TL;DR: In this article, a model is presented for predicting the size reduction of particles coupled with the flow field in pipeline conveying, where the particles are described as individual discrete entities within a representative mass.
TL;DR: In this paper, an experimental study on a selected coal wash is undertaken to characterize the influence of compaction and particle breakage on its corresponding stress-strain behavior and the critical state conditions for coal wash seem to be better described through a threedimensional surface incorporating the effect of breakage.
Abstract: Coal wash is a granular waste material that is readily available in the vicinity of coal mining operations. While its potential use in structural fills has been recognized in the past, the effects of particle breakage on the geomechanical performance of the material have not been thoroughly investigated. In this paper, an experimental study on a selected coal wash is undertaken to characterize the influence of compaction and particle breakage on its corresponding stress-strain behavior. Particular emphasis is given to the role of compaction energy level and associated breakage incurred during compaction on the drained and undrained shearing behavior. The incidence of particle breakage for undrained and drained shearing was observed to be different, which in turn had a strong influence in the yielding behavior and the critical state. Furthermore, the critical state conditions for coal wash seem to be better described through a three-dimensional surface incorporating the effect of breakage.
TL;DR: In this paper, the effect of size and shape in single particle breakage of pegmatite was evaluated using drop weight test and the results showed that the shape of particle does have an influence on the breakage function.
TL;DR: In this paper, the breakage rates of two pharmaceutical excipients, microcrystalline cellulose (MCC) and mannitol, were determined with two different approaches, i.e. by analysing the milling mass throughput and the change in mass in the largest granule size class.
TL;DR: In this paper, the authors investigated breakage probabilities of ore during these repetitive impacts using a JKRBT (Rotary Breakage Tester) so as to minimise variability in applied energy.
TL;DR: In this article, the effect of load duration on particle breakage and dilative behavior of a residual soil was investigated and the linearity was observed between the shear stress ratio and the dilation rate.
Abstract: This paper presents an experimental investigation of the effect of load duration on particle breakage and dilative behavior of a residual soil. To deepen the understanding of particle breakage subjected to load duration, the large-scale monotonic triaxial (TX) tests and creep TX tests were conducted on residual soil in saturated conditions. Values of particle breakage for the monotonic loading condition are compared with corresponding values for the creep loading condition calculated using a relative breakage index. For the creep TX tests, the load duration results in >1.5 times greater breakage index than the values of the monotonic TX test did. The obtained results suggest that load duration and stress level beneficially influence the particle breakage in the form of dilation suppression. The linearity is observed between the shear stress ratio and the dilation rate. A cycle with three phases is provided to help understand the creep behavior of coarse-grained residual soil: the concentration of ...
TL;DR: In this paper, the role of dispersion stages (nozzle and dispersion cloud turbulence) on particle breakage and compare the performance of a dispersion system to that of a standard 20-L apparatus is examined.
Abstract: Dust explosion hazards can be described with parameters such as MIE, MEC, P max , K st etc., which are known to depend on particle size distribution within a dust cloud. Literature has shown the dispersion system (outlet valve, in particular) in a standard 20-L dust explosion apparatus breaks the dust into smaller particles leading to explosion parameters not necessarily corresponding to the original size. This study uses a novel dispersion system in a 36-L dust explosion apparatus to eliminate the mechanical shearing from the outlet valve and investigates its effect on dust particle integrity. The study also aims to observe the role of dispersion stages (nozzle and dispersion cloud turbulence) on particle breakage and compare the performance of our dispersion system to that of a standard 20-L apparatus. In addition, the role of dust dispersion concentration on particle breakage is examined. Anthraquinone, Acetaminophen (Paracetamol) and Ascorbic Acid are used to accomplish the goals of the study. Finally, the effect of dispersion on a nanomaterial is investigated using Carbon Nanofibers (CNFs). Anthraquinone, Acetaminophen and Ascorbic Acid show that even in the absence of an outlet valve, significant particle breakage occurs. This demonstrates the major role of both the dispersion nozzle and cloud turbulence in particle breakage. In addition, the experiments revealed dispersion concentration to be an important factor in particle breakage and helped establish the inverse relation between particle breakage and dust dispersion concentration. Nanomaterial experiments with CNFs show significant de-agglomeration in the dispersion cloud followed by re-agglomeration.
TL;DR: The time evolution of the normalized average size of the fragments generated by the breakup process could be scaled using a unique dimensionless time defined by multiplying the real time with the cluster breakage rate constant (τ = t·kB).
Abstract: We have studied the long-term dynamics of shear-induced breakage of individual colloidal clusters, covering a wide range of fractal dimensions, using Stokesian dynamics. We found that the time evolution of the normalized average size of the fragments generated by the breakup process could be scaled using a unique dimensionless time defined by multiplying the real time with the cluster breakage rate constant (τ = t·kB). Clusters with different masses but the same fractal dimension exhibited almost identical breakage dynamics when exposed to equal overall hydrodynamic forces (ηγRg,02). The steady-state values of the average size, mass, and standard deviation of fragment mass distribution showed a universal scaling depending only on the overall hydrodynamic force, irrespective of the initial cluster properties. We also identified two asymptotic regimes for the evolution of the fractal dimension, ⟨df⟩, of fragments: open clusters (df ≤ 2.1) produced dense fragments with a limiting ⟨df⟩ ≈ 2.4 ± 0.1; conversely...
TL;DR: In this paper, an experimental and computational study of agglomeration and breakage processes for fully destabilized latex particles under turbulent flow conditions in a jar is presented, where the particle size distribution and the fractal dimension of flocs of latex particles were monitored using an on-line laser diffraction technique.
TL;DR: In this article, a wide-size JKMRC Rotary Breakage Tester (JKRBT) characterisation method was developed, where mixed particles in 13.2-45mm size range were tested as one size class in the JKRBT by single-particle breakage mode.
TL;DR: Shi and Kojovic as discussed by the authors used the JK size-dependent breakage model to smooth the energy-size reduction relationship and predict crusher energy requirement, to explain the non-linear response of power station grinding mill capacity with the coal grindability index HGI, and to estimate specific energy reduction resulting from the high voltage pulse pre-weakening effect.
TL;DR: In this paper, the effect of porosity on attrition of spray-dried powders has been investigated by scanning electron microscopy (SEM) and X-ray microtomography (XRT).
TL;DR: In this article, the strength distribution and the breakage functions of particles of four different materials subjected to uniaxial compressive loading were developed, and the parameters of logistic function and breakage function were obtained by curvefitting of the functions to the strength and size distribution of the fragments, respectiv...
Abstract: Particle breakage is a common problem in the conveying and handling of particulate solids. The phenomenon of particle breakage has been studied by experiments by a number of researchers in order to describe the process of breakage by mathematical functions. The development of comminution functions that can suitably describe the breakage behavior of granular materials can lead to a significant improvement in the design and efficiency of particulate solids handling equipment. The present study focuses on developing the strength distribution and the breakage functions of particles of four different materials subjected to uniaxial compressive loading. Single particles were compressed until fracture in order to determine their strength distribution and the fragments were investigated to determine their size distribution. The parameters of logistic function and breakage function were obtained by curve-fitting of the functions to the strength distribution and size distribution of the fragments, respectiv...