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1
Liu, Yuan-Yuan, Yaping Zhang, Yanrong Li, and Yi-Chen Guo. "Combined Influence of Particle Shape and Fabric on the Shear Behaviour of Granular Materials." Advances in Materials Science and Engineering 2022 (November 23, 2022): 1–15. http://dx.doi.org/10.1155/2022/5993323.
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The anisotropy feature is an important characteristic of granular materials in natural life and is caused by two facts: the anisotropy feature of particle shape, such as an elongated or flattened shape, and the anisotropy feature of the packing fabric, such as the preferable orientation of particle alignment. The discrete element method has been commonly used in the study of meso-mechanics of granular materials and is in our study to simulate the direct shear test with particles of various aspect ratios under different initial orientation alignment conditions for assessing the coupled influence of anisotropy from particle shape and fabric of particle packings on the shear behaviour of granular materials. Analysis results show that anisotropy from the particle shape has the most significant influence on the shear behaviour of a granular packing when the packing has the initial anisotropy fabric of an orientational alignment perpendicular to the shear direction. Moreover, the initial fabric anisotropy of a granular packing has an increasing influence with the rise in anisotropy of particle shape. A combined anisotropic factor is finally introduced to reflect the coupled influence of the shape anisotropy of particles and the fabric anisotropy of particle packings.
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Iniyatova, Gulfairuz, Assiya Yermukhambetova, Aidana Boribayeva, and Boris Golman. "Approximate Packing of Binary Mixtures of Cylindrical Particles." Micromachines 14, no. 1 (December 23, 2022): 36. http://dx.doi.org/10.3390/mi14010036.
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Particle packing plays an essential role in industry and chemical engineering. In this work, the discrete element method is used to generate the cylindrical particles and densify the binary cylindrical particle mixtures under the poured packing conditions. The influences of the aspect ratio and volume fraction of particles on the packing structure are measured by planar packing fraction. The Voronoi tessellation is used to quantify the porous structure of packing. The cumulative distribution functions of local packing fractions and the probability distributions of the reduced free volume of Voronoi cells are calculated to describe the local packing characteristics of binary mixtures with different volume fractions. As a result, it is observed that particles with larger aspect ratios in the binary mixture tend to orient randomly, and the particles with smaller aspect ratios have a preferentially horizontal orientation. Results also show that the less dense packings are obtained for mixtures with particles of higher aspect ratios and mixtures with a larger fraction of elongated cylindrical particles.
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Miao, Yinghao, Xin Liu, Yue Hou, Juan Li, Jiaqi Wu, and Linbing Wang. "Packing Characteristics of Aggregate with Consideration of Particle size and Morphology." Applied Sciences 9, no. 5 (February 28, 2019): 869. http://dx.doi.org/10.3390/app9050869.
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The packing characteristics of aggregates are very important for aggregate blend design, which is closely related to the performance of mixtures. In this study, an indoor packing experiment was designed to investigate the behaviors of single-size particle packing and two-size particle packing. The effects of particle composition, particle size and size ratio, particle morphology on packing characteristics were also evaluated. Two kinds of aggregates (crushed stone and gravel) with significant morphological differences were selected for the test. The angularity of the aggregates was quantitatively analyzed using the variance of mean curvature ( S C m 2 ) of particle surface in accordance with the 3-D scanning measurements. Based on the test results, the packing characteristics of aggregates were analyzed using the air void content (Va) and the packing function index (Ipf) proposed in this paper. It is shown that the analysis results of packed ideal spheres cannot be directly used to describe the packing characteristics of aggregates. Particle morphology has a significant impact on packing characteristics, especially on the Va. The Va of packed aggregates with poor angularity is significantly smaller than that with good angularity. Ipf can be used to quantitatively distinguish the packing function of particles. The test results show that the packing function of particles cannot be simply divided into the skeleton building and air voids filling. Generally, the particles in packed blend have both of these functions. The packing function of particles depends not only on the particle size, but also on the composition of particles with different size. When the size ratio and volume ratio are the same, the packing characteristics of the two-size particle blends will still change with the change of the particle size. The exploration of packing behaviors of single- size and two- size particle aggregates is helpful for analyzing the packing behaviors of blends with multi-size particles.
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Wiącek, Joanna, Mateusz Stasiak, and Jalal Kafashan. "Structural and Micromechanical Properties of Ternary Granular Packings: Effect of Particle Size Ratio and Number Fraction of Particle Size Classes." Materials 13, no. 2 (January 11, 2020): 339. http://dx.doi.org/10.3390/ma13020339.
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The confined uniaxial tests of packings with discrete particle size distribution (PSD) were modeled with the discrete element method. Ternary packings of spheres with PSD uniform or nonuniform by number of particles were examined in three-dimensional (3D) system. The study addressed an effect of the particle size ratio and the particle size fraction on structural and micromechanical properties of mixtures. A study of packing structure included porosity and coordination numbers, while the investigation of micromechanical properties included distribution of normal contact forces and stress transmission through the packing. A micro-scale investigation of the effect of particle size ratio on structure and mechanics of the ternary packings revealed a strong relationship between the properties of sample and the value of parameter till its critical value was reached. A further increase in particle size ratio did not significantly affect properties of packings. Contrary to the porosity and coordination numbers, the partial stresses were highly affected by the fraction of particle size classes in ternary mixtures. The contribution of the partial stress into the global stress was determined by number fraction of particles in packings with small particle size ratio, while it was mainly determined by particle size ratio in packings with small particle size ratio.
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Jiang, Haoran, Reid Kawamoto, and Takashi Matsushima. "Exploring the combined effect of particle shape and friction on cell structures in granular packings via LS-DEM modeling." IOP Conference Series: Earth and Environmental Science 1330, no. 1 (May 1, 2024): 012047. http://dx.doi.org/10.1088/1755-1315/1330/1/012047.
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Abstract To comprehensively understand and predict the macroscopic behavior of a granular system, one must consider not only the properties of individual particles but also the local structures. In this study, we prepare mechanically stable granular packings of super disks using the two-dimensional level set discrete element method (LS-DEM). We identify the cells, the irreducible loops enclosed by contacting particles, in the prepared granular packings and then analyze the statistics of these structures. We find the following. (1) The packing fraction or mean coordination number of studied systems exhibits a non-trivial dependency on particle shapes and inter-particle frictions, making it challenging to establish a direct correlation between them. (2) Using the cell-based description as a bridge, we can measure the packing behavior without considering the influence of particle shape and inter-particle friction. Specifically, the mean coordination number can be explicitly represented as a function of the mean cell order according to Euler’s topological relation. Upon the assumption that all cells are regular polygons, we can also approximately estimate the rattlers-free packing fraction via the mean cell order. (3) We have observed a nearly linear relationship between the mean cell order and rattler fraction. This enables us to determine the packing fraction as well.
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Zhao, Tingting, Y. T. Feng, and Yuanqiang Tan. "Characterising 3D spherical packings by principal component analysis." Engineering Computations 37, no. 3 (November 21, 2019): 1023–41. http://dx.doi.org/10.1108/ec-05-2019-0225.
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Purpose The purpose of this paper is to extend the previous study [Computer Methods in Applied Mechanics and Engineering 340: 70-89, 2018] on the development of a novel packing characterising system based on principal component analysis (PCA) to quantitatively reveal some fundamental features of spherical particle packings in three-dimensional. Design/methodology/approach Gaussian quadrature is adopted to obtain the volume matrix representation of a particle packing. Then, the digitalised image of the packing is obtained by converting cross-sectional images along one direction to column vectors of the packing image. Both a principal variance (PV) function and a dissimilarity coefficient (DC) are proposed to characterise differences between different packings (or images). Findings Differences between two packings with different packing features can be revealed by the PVs and DC. Furthermore, the values of PV and DC can indicate different levels of effects on packing caused by configuration randomness, particle distribution, packing density and particle size distribution. The uniformity and isotropy of a packing can also be investigated by this PCA based approach. Originality/value Develop an alternative novel approach to quantitatively characterise sphere packings, particularly their differences.
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Amano, Yuto, Takashi Itoh, Hoshiaki Terao, and Naoyuki Kanetake. "Prediction of Packing Density of Milled Powder Based on Packing Simulation and Particle Shape Analysis." Materials Science Forum 534-536 (January 2007): 1621–24. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.1621.
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For precise property control of sintered products, it is important to know the powder characteristics, especially the packing density of the powder. In a previous work, we developed a packing simulation program that could make a packed bed of spherical particles having particle size distribution. In order to predict the packing density of the actual powder that consisted of nonspherical particles, we combined the packing simulation with a particle shape analysis. We investigated the influence of the particle size distribution of the powder on the packing density by executing the packing simulation based on particle size distributions of the actual milled chromium powders. In addition, the influence of the particle shape of the actual powder on the packing density was quantitatively analyzed. A prediction of the packing density of the milled powder was attempted with an analytical expression between the particle shape of the powder and the packing simulation. The predicted packing densities were in good agreement with the actual data.
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Sun, Shaobo, Huisu Chen, and Jianjun Lin. "A Universal Method for Modeling and Characterizing Non-Circular Packing Systems Based on n-Point Correlation Functions." Materials 15, no. 17 (August 30, 2022): 5991. http://dx.doi.org/10.3390/ma15175991.
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A universal method for modeling and characterizing non-circular particles is developed. The n-point correlation functions (n = 1, 2 and 3) are efficiently computed with a GPU parallel computing procedure. An algorithm for dynamic packing of impenetrable non-circular particles is developed based on the fast estimation of overlap information using a one-point correlation function. The packing algorithm is independent of particle shape and proved to be reliable by examples of polygons and super-ellipses. In addition, penetrable packings are generated in an efficient and precise way. Using a two-point correlation function, these non-circular packs are accurately characterized and compared in terms of features such as penetrable and impenetrable, packing fraction and particle shape. In addition, three-point correlation functions are also illustrated and discussed.
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Dinger, Dennis R., and James E. Funk. "Particle-Packing Phenomena and Their Application in Materials Processing." MRS Bulletin 22, no. 12 (December 1997): 19–23. http://dx.doi.org/10.1557/s0883769400034692.
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Particle packing is directly controlled by the particle-size distribution of a material being processed. For this reason, particle packing is important to all particulate/fluid systems. After the solids fraction of a body is defined, interparticle chemistry controls how the body will pack and flow. A system of powders can never pack better than the maximum possible level defined by the particle-size distribution alone. Proper control of interparticle chemistry however can help achieve maximum packing, can be used to open the structure, and/or can be used to modify rheological or other process properties.The main goals of particle-packing research have been to determine how systems of particles pack, to develop algorithms for calculating packing densities and porosities for any distribution of particles (spherical or nonspherical, rough or smooth, wet or dry), and to determine how packing and its properties affect the variety of industrial operations that utilize particulate/fluid systems.
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Wang, Yutao, Wei Deng, Zhaohui Huang, and Shuixiang Li. "Descriptor-free unsupervised learning method for local structure identification in particle packings." Journal of Chemical Physics 156, no. 15 (April 21, 2022): 154504. http://dx.doi.org/10.1063/5.0088056.
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Local structure identification is of great importance in many scientific and engineering fields. However, mathematical and supervised learning methods mostly rely on specific descriptors of local structures and can only be applied to particular packing configurations. In this work, we propose an improved unsupervised learning method, which is descriptor-free, for local structure identification in particle packing. The point cloud is used as the input of the improved method, which directly comes from spatial positions of particles and does not rely on specific descriptors. The improved method constructs an autoencoder based on the point cloud network combined with Gaussian mixture models for dimension reduction and clustering. Numerical examples show that the improved method performs well in local structure identification of quasicrystal disk and sphere packings, achieving comparable accuracy with previous methods. For disordered packings, which have been considered having nearly no local structures, the improved method identifies a nontrivial seven-neighbor motif in the maximally dense random packing of disks and finds acentric structural motifs in the random close packing of spheres, which demonstrate the ability on identification of new and unknown local structures. The improved unsupervised learning method would help obtain information from massive simulation and experimental results as well as devising new order parameters for particle packings.
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Chen, Yuan, Didier Imbault, and Pierre Dorémus. "Numerical Simulation of Cold Compaction of 3D Granular Packings." Materials Science Forum 534-536 (January 2007): 301–4. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.301.
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During cold compaction processes loose powder is pressed under tooling action in order to produce complex shaped engineering components. Here, the analysis of the plastic deformation of granular packings is of fundamental importance to the development of computer simulation models for industrial forming processes. Powders can be idealized by packing discrete particles, where each particle is a sphere meshed with finite elements. During pressing, particles are deformed by elastic-plastic hardening where friction is present at each contact. The pressing of an isolated particle followed by a body centered cubic packing was compared with numerical prediction and experimental data. The analysis was focused on the interaction between particles and the global response expressed in force-displacement curve during compaction. The accuracy of the numerical models was also analyzed for high relative densities up to 0.95.
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Guo, Ye, Xin Huang, and Bao Lin Zhu. "A Calculation Method for Packing Density of Powder in Paste with Continuous Grain Size Distribution." Key Engineering Materials 477 (April 2011): 125–31. http://dx.doi.org/10.4028/www.scientific.net/kem.477.125.
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By regarding the powder particles warpped with water film as compounded particles, the packing density of powder particles in actual paste system is transformed into the packing density of compounded partcles in imaginary dry-particle system. Based on Stovall Model, a calculation method for packing density of powder with continuous particle size distribution in paste is developed, and the parameters in the method are dentified by experiment. This calculation method could be used to simulate the packing density of cementitious materials such as cement, fine slag, and fly ashes.
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Roy, D. M., B. E. Scheetz, and M. R. Silsbee. "Processing of Optimized Cements and Concretes Via Particle Packing." MRS Bulletin 18, no. 3 (March 1993): 45–49. http://dx.doi.org/10.1557/s088376940004389x.
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It has been well-recognized for many years that the particle-size distributions of the cement and the grading of the aggregates play an important role in determining the properties and characteristics of cement and concrete products. DSP (densified with small particles) type cements and concretes, to a certain extent, MDF (macro-defect-free) cements, and optimized concretes are recently recognized outstanding examples of the application of this principle. The preset characteristics of the cementitious slurry are also strongly influenced by these factors. Both the workability of the fresh material, and the microstructure development are controlled to a considerable extent by these geometric parameters.Two seminal works in the areas of continuous particle size distributions and particle packing are those of Andreason and Furnas, respectively. Furnas deals mainly with discrete systems and Andreason with continuous distributions. As early as 1907, the concept of idealized particle packing was being used to optimize cements and concretes. Figure 1a shows an idealized cross section of a simple cubic packing of monodispersed spheres. This system has a maximum packing density of 0.65%. In an ideally packed system of discrete size ranges, the size of the next smallest particles would be such that they just fit in the gaps between the largest size particles, and so on for subsequent particle sizes; this system is represented schematically in Figure 1b. Not only the sizes but also the relative numbers of particles are important; Figures 1c and 1d show systems where some fraction of the smaller and larger particle sizes, respectively, are missing. Figure 1e shows a system where the size of the second largest particles is too large to fit into the gaps between the largest particles, resulting in a lower packing efficiency. Thus, both the particle size and fractions are important when considering packing efficiency.
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Dodds, JohnA. "Particle packing characteristics." Powder Technology 61, no. 1 (April 1990): 101. http://dx.doi.org/10.1016/0032-5910(90)80071-6.
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Lee, Jong-Heon, W. Jack Lackey, and James F. Benzel. "Ternary packing of SiC and diamond particles in ethanol." Journal of Materials Research 11, no. 11 (November 1996): 2804–10. http://dx.doi.org/10.1557/jmr.1996.0355.
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Particle packing techniques employing a liquid phase were used for preparation of dense disks of SiC and diamond particulates. Forty-one SiC and fifteen diamond compositions in the ternary-component particle systems were used to determine the optimum percentages of coarse, medium, and fine particles for achieving high packing densities: over 80% for SiC and over 62% for diamond. High packing densities were achieved without vibration by simply mixing the three size fractions in ethanol followed by stirring during the initial evaporation stage. The packing density results for SiC were successfully correlated with the percentages of the coarse and fine particles using multiple regression analysis; however, the data for diamond could not be similarly correlated with particle composition because the experimental work was done in a narrow range of compositions and the range of packing densities was small.
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Tung, K. L., Y. L. Chang, J. Y. Lai, C. H. Chang, and C. J. Chuang. "A CFD study of the deep bed filtration mechanism for submicron/nano-particle suspension." Water Science and Technology 50, no. 12 (December 1, 2004): 255–64. http://dx.doi.org/10.2166/wst.2004.0721.
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The mechanism of the deep bed filtration for submicron and nano particles suspension was conducted by means of a force analysis on the suspended particles flow path through order-packed granular filter beds. The flow fields through the filter beds were calculated by using the commercial available CFD software - Fluent. Various types of granular packing structures, such as the simple cubic packing, bodycentered packing and face-centered packing structures were chosen for analysis. The motion of suspended particle of 2.967, 0.816, 0.460 and 0.050 μm in diameter, respectively, were tracked by considering the following forces including a net gravitational force, hydraulic drag force, lift force, Brownian force, van der Waals force and a double layer force. The effects of the granular bed packing structure, the porosity of these beds and the suspended particle diameter on the capture efficiency of a granular filter bed were examined. The force analysis depicts that the inertial effect and van der Waals force increased the capture probability of particles on the granular filter bed while the lift force and the Brownian force decreased the particle deposition. Simulated results show that among the chosen packing structures, the face-center packed granular bed gives the greatest pressure drop and capture efficiency of particles due to the lower packing porosity. The simple cubic packed filter bed showed the lowest pressure drop and capture efficiency of particles due to the greatest packing porosity among the chosen packing structures. It is mainly due to the simple cubic packing structure in which there exists the free vertical downward flowing path and thus exhibits a higher packing porosity. The comparisons of the simulated capture efficiency with experimental results depicted that the body-centre packed granular bed showed the best approximation of capture efficiency compared to that of the randomly packed granular bed.
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Wang, Dong, Nima Nejadsadeghi, Yan Li, Shashi Shekhar, Anil Misra, and Joshua A. Dijksman. "Rotational diffusion and rotational correlations in frictional amorphous disk packings under shear." Soft Matter 17, no. 34 (2021): 7844–52. http://dx.doi.org/10.1039/d1sm00525a.
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Particles in a packing will rotate when the packing is deformed. We find that rotations display diffusive dynamics set by particle friction and packing fraction. Rotations are spatially anticorrelated and directly indicative of the system pressure.
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LIU Zelin, YUAN Houfei, ZENG Zhikun, GE Zhuan, JIANG Yonglun, and WANG Yujie. "Structural Study of Binary Hard-sphere Packing under Tapping." Acta Physica Sinica 74, no. 13 (2025): 0. https://doi.org/10.7498/aps.74.20250232.
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The packing behavior and mechanical properties of granular materials play a critical role in various engineering applications, including materials handling, construction, and energy storage. Although significant progress has been made in understanding the packing of monodisperse spheres, real-world granular systems often exhibit polydispersity, where particles of different sizes coexist. Binary systems, where the particle size ratio is adjustable, serve as a simplified model to study the structural and dynamical properties of granular materials. However, most theoretical studies on binary systems have focused on idealized frictionless models, neglecting the coupled effects of friction and preparation history, and experimental data for three-dimensional systems remain limited. This study seeks to address these gaps by investigating the packing behavior of binary hard spheres under tapping, using advanced experimental techniques such as X-ray computed tomography (CT) and tap-driven compaction. We systematically explore the effects of particle size ratio and tap intensity on the packing fraction and local structure of binary granular systems. The experimental results show that the steady-state packing fraction decreases as tap intensity increases, exhibiting similar behavior across different composition ratios. Additionally, the compaction dynamics are quantified using the Kohlrausch-Williams-Watts (KWW) relaxation function, revealing that the relaxation time decays exponentially with tap intensity, independent of the composition ratios. Voronoi cell analysis demonstrates that the local volume distribution of both big and small particles in binary systems follows statistical patterns similar to monodisperse systems. Notably, as tap intensity decreases, the system density increases, and volume fluctuations decrease, mirroring trends observed in monodisperse packings. Furthermore, the study highlights the influence of friction on the packing structure. For binary systems, big particles, with rougher surfaces, pack more loosely than smaller particles, and the coordination number increases with the proportion of smaller particles. This suggests that frictional interactions between particles play a significant role in determining the packing density and structural stability of granular materials. The average coordination number and the steady-state packing fraction are found to be weakly dependent on each other, with friction and tap intensity (or effective temperature) being the primary factors affecting the system's structural characteristics. These findings provide a comprehensive experimental framework for understanding the packing behavior of binary granular systems, with important implications for material design in industrial applications. The study contributes to the development of a more complete statistical mechanical theory for granular materials, incorporating both frictional effects and the influence of preparation history. Future research may extend these findings to more complex particle size distributions and explore the relationship between structural and mechanical properties.
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Dandekar, Rahul, and P. L. Krapivsky. "Dynamic space packing." Journal of Statistical Mechanics: Theory and Experiment 2023, no. 10 (October 1, 2023): 103403. http://dx.doi.org/10.1088/1742-5468/ad0223.
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Abstract Dynamic space packing (DSP) is a random process with sequential addition and removal of identical objects into space. In the lattice version, objects are particles occupying single lattice sites, and adding a particle to a lattice site leads to the removal of particles on neighboring sites. We show that the model is solvable and determine the steady-state occupancy, correlation functions, desorption probabilities, and other statistical features for the DSP of hyper-cubic lattices. We also solve a continuous DSP of balls into R d .
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Nagy, Endre. "On the three-phase mass transfer with solid particles adhered to the gas-liquid interface." Open Chemistry 1, no. 2 (June 1, 2003): 160–77. http://dx.doi.org/10.2478/bf02479266.
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AbstractA heterogeneous, multi-layer mass transfer model is proposed for prediction of the effect of multi-layer packing of catalyst particles adhered to the gas-liquid interface. The behavior of the mass transfer rate with respect to the multi-layer packing, to the particle size and mass transfer coefficient without particles is discussed. It is shown that enhancement can be considerably increased by multi-layer packing compared to that of mono-layer packing, depending on the values of particle size and mass transfer coefficient. The predicted mass transfer rates using the proposed model was verified with experimental data taken from the literature. The model presented should be superior to that of published in the literature.
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Sudduth, Richard D. "Optimum formulation derivation for the ultimate packing fraction using monodispersed particle sizes when optimizing suspension viscosities." Pigment & Resin Technology 48, no. 1 (January 7, 2019): 45–56. http://dx.doi.org/10.1108/prt-01-2018-0006.
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Purpose The importance of maximizing the particle packing fraction in a suspension by maximizing average particle size ratio of D5/D1 has been adequately shown to be important as previously reported in the literature. This study aims to extend that analysis to include the best formulation approach to maximize the packing fraction with a minimum number of monodisperse particle sizes. Design/methodology/approach An existing model previously developed by this author was modified theoretically to optimize the ratio used between consecutive monodisperse particle sizes. This process was found to apply to a broad range of particle configurations and applications. In addition, five different approaches for maximizing average particle size ratio D̅5/D̅1 were addressed for blending several different particle size distributions. Maximizing average particle size ratio D̅5/D̅1 has been found to result in an optimization of the packing fraction. Several new concepts were also introduced in the process of maximizing the packing fraction for these different approaches. Findings The critical part of the analysis to maximize the packing fraction with a minimum number of particles was the theoretical optimization of the ratio used between consecutive monodisperse particle sizes. This analysis was also found to be effectively independent of the maximum starting particle size. This study also clarified the recent incorrect claim in the literature that Furnas in 1931 was the first to generate the maximum theoretical packing fraction possible for n different particles that was actually originally developed in conjunction with the Sudduth generalized viscosity equation. In addition, the Furnas generated equation was also shown to give significantly different results from the Sudduth generated equation. Research limitations/implications Experimental data involving monodisperse particles of different blends with a minimum number of particle sizes that are truly monodisperse are often extremely difficult to obtain. However, the theoretical general concepts can still be applicable. Practical implications The expanded model presented in this article provides practical guidelines for blending pigments using a minimum number of monodisperse particle sizes that can yield much higher ratios of the particle size averages D̅5/D̅1 and thus potentially achieve significantly improved properties such as viscosity. Originality/value The model presented in this article provides the first apparent guidelines to control the blending of pigments in coatings by the optimization of the ratio used between consecutive monodisperse particle sizes. This analysis was also found to be effectively independent of the maximum starting particle size.
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Yu, Weixiao, Yun Li, Zhipeng Liang, Jiaxi Wu, Sudi Wang, and Yinghao Miao. "Laboratory Investigation of Packing Characteristics and Mechanical Performance of Aggregate Blend." Materials 18, no. 9 (April 25, 2025): 1953. https://doi.org/10.3390/ma18091953.
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Aggregates are the main material forming the skeleton structure of asphalt mixtures and are of great importance to resist external load for asphalt pavement. This study analyzed the packing characteristics and mechanical performance of aggregate blend to provide a reference for improving the bearing capacity of asphalt mixtures. The single-size, two-size, and multi-size aggregate blends were chosen to conduct the laboratory packing and California bearing ratio (CBR) tests. Six particle sizes were selected to design the single-size aggregate blends. Six size combinations were included and various mass ratios were considered for each size combination in the two-size aggregate blends. The multi-size aggregate blends were designed through the gradually filling method according to stone matrix asphalt with a nominal maximum particle size (NMPS) of 16 mm (SMA16) and dense asphalt concrete with an NMPS of 26.5 mm (AC25). The packing characteristics of the blends were quantified by the air voids and the percentage of contribution to the packing volume (PCPV). The mechanical performance of the blends was analyzed by the CBR value. The relationship between packing characteristics and mechanical performance was explored by data fitting. The results showed that the particle size and the size ratio have an effect on the packing characteristics and mechanical performance of aggregate blend. The smaller the particle size, the larger the air void of the blend. The blends composed of larger particles have better load bearing capacity than those composed of smaller particles. The larger the particle size ratio, the greater the air void of the blend and the weaker the load bearing capacity. The particles smaller than 1.18 mm and those smaller than 0.3 mm in AC25 mainly play a role in filling the voids and have little contribution to the load bearing. There is a certain correlation between the packing characteristics and mechanical performance of aggregate blend.
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Yang, Zon-Yee, and Shin-Chen Lo. "Describing the geometrical packing of gravelly cobble deposits using pair-correlation functions." Canadian Geotechnical Journal 38, no. 6 (December 1, 2001): 1343–53. http://dx.doi.org/10.1139/t01-065.
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There is a close correlation between the mechanical behavior of gravelly cobbles and their geometrical fabric. In geotechnical engineering, the particle-size distribution curve is used to describe the particle gradation. However, a group of particles with the same particle-size distribution can result in several packing arrangements due to the different sedimentation processes. The particle-size distribution curve does not distinguish this characteristic. This study attempts to employ the pair-correlation function of point field theory for describing the geometric packing of gravelly cobble deposits. In the point field, a single gravel- or cobble-sized particle is represented by a point of its geometric center. The pair-correlation function can statistically illustrate the characteristics of a geometrical point pattern and is helpful in interpreting the neighborhood relationship between particles, such as the frequency of interpoint distances and the dominant particle sizes in a point process. Some examples based on ideal particle shapes and arrangements are analyzed to illustrate the interpretations from the pair-correlation functions. The characteristics of pair-correlation functions of field examples are also explained. It is shown that the pair-correlation function can provide another approach to understanding the geometrical packing characteristics of a gravelly cobble formation.Key words: gravelly cobble deposit, geometrical packing, interpoint distance, particle-size distribution, pair-correlation function, point field theory.
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Huang, Qiu An, Geng Guang Xu, and Jian Yu Chen. "Research of the Particle Gradation Technology of Components in PBX Explosive Based on CPM Model." Applied Mechanics and Materials 727-728 (January 2015): 366–69. http://dx.doi.org/10.4028/www.scientific.net/amm.727-728.366.
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Basedon the assumption of related parameters in compressible packing model, thecompressible packing model was used for the calculation of the explosivespacking efficiency. The accuracy of the calculation was verified by experimentsand the relative error was 2.49%. Besides, the influence of content offineparticles and particle size distribution in explosives on stacking efficiencywas discussed. The results show that the stacking efficiency was increasingwith the particle size distribution increasing from 0~300μm to 0~700μm. Thepacking efficiency reached it’s maximum value when we only increased thecontent of fine particles to 40%. Therefore, the packing efficiency has arelation with particle size distribution of raw materials.
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Teich, Erin G., Greg van Anders, Daphne Klotsa, Julia Dshemuchadse, and Sharon C. Glotzer. "Clusters of polyhedra in spherical confinement." Proceedings of the National Academy of Sciences 113, no. 6 (January 25, 2016): E669—E678. http://dx.doi.org/10.1073/pnas.1524875113.
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Dense particle packing in a confining volume remains a rich, largely unexplored problem, despite applications in blood clotting, plasmonics, industrial packaging and transport, colloidal molecule design, and information storage. Here, we report densest found clusters of the Platonic solids in spherical confinement, for up to N=60 constituent polyhedral particles. We examine the interplay between anisotropic particle shape and isotropic 3D confinement. Densest clusters exhibit a wide variety of symmetry point groups and form in up to three layers at higher N. For many N values, icosahedra and dodecahedra form clusters that resemble sphere clusters. These common structures are layers of optimal spherical codes in most cases, a surprising fact given the significant faceting of the icosahedron and dodecahedron. We also investigate cluster density as a function of N for each particle shape. We find that, in contrast to what happens in bulk, polyhedra often pack less densely than spheres. We also find especially dense clusters at so-called magic numbers of constituent particles. Our results showcase the structural diversity and experimental utility of families of solutions to the packing in confinement problem.
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Pykhtin, A. A., I. D. Simonov-Emelyanov, A. N. Kovaleva, and K. S. Tsvetkova. "Characteristics of shungite particles of different fractional composition and design of compositions of particulate-filled polymer composite materials with different types of structures." Plasticheskie massy, no. 4 (September 1, 2024): 31–37. http://dx.doi.org/10.35164/0554-2901-2024-04-31-37.
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The paper presents the results of studies of technological properties (bulk and true density, particle size of the general fraction, particle size distribution, packing coefficient and maximum packing degree of filler particles, etc.) of shungite particles of different batches produced by LLC Nadvoitsky TDM Plant LLC (Karelia, RF).For the first time for shungite particles of different sizes the values of packing density (kуп) and maximum content of dispersed phase (φm) in DFPCM were determined, which allows to calculate generalized and reduced structure parameters, to carry out classification by structural principle and to design compositions of high-tech polymer composites with given properties.Practically all possible compositions of DFPCM with shungite particles of different sizes and different types of disperse structure are presented.
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Cárdenas-Barrantes, Manuel, David Cantor, Jonathan Barés, Mathieu Renouf, and Emilien Azéma. "A micro-mechanical compaction model for granular mix of soft and rigid particles." EPJ Web of Conferences 249 (2021): 02008. http://dx.doi.org/10.1051/epjconf/202124902008.
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We use bi-dimensional non-smooth contact dynamics simulations to analyze the isotropic compaction of mixtures composed of rigid and deformable incompressible particles. Deformable particles are modeled using the finite-element method and following a hyper-elastic neo-Hookean constitutive law. The evolution of the packing fraction, bulk modulus and particle connectivity, beyond the jamming point, are characterized as a function of the applied stresses for different proportion of rigid/soft particles and two values of friction coefficient. Based on the granular stress tensor, a micro-mechanical expression for the evolution of the packing fraction and the bulk modulus are proposed. This expression is based on the evolution of the particle connectivity together with the bulk behaviour of a single representative deformable particle. A constitutive compaction equation is then introduced, set by well-defined physical quantities, given a direct prediction of the maximum packing fraction φmax as a function of the proportion of rigid/soft particles.
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Cao, De Wen, Jia Huan Wang, Yu Qing Sun, Ke Hua Chen, Cheng Ming Yu, and Ping Ju Li. "The Effect of the Microstructure of Semisolid Al Alloy on its Rheology." Applied Mechanics and Materials 490-491 (January 2014): 109–12. http://dx.doi.org/10.4028/www.scientific.net/amm.490-491.109.
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In the present work, the effect of the microstructure of AlSi6Mg2 alloy on its macro-rheological behavior of the steady AlSi6Mg2 alloy is investigated. Specifically, the effect of particle size, packing mode and degree of the agglomeration of particles are analyzed. It can be seen that the apparent viscosity decreases with increasing the particle size (d) ifdis between a few μm and 200 μm, while the solid particle size does not affect viscosity except this region. This theoretical prediction is in qualitatively agreement with the experimental data. The trend of the variation of the average agglomerate size with the particle size is the same as the one of viscosity. The packing mode of solid particles in agglomerate is closely related to the solid volume fraction and the characteristics of the alloy system. Subsequently, the state of agglomeration of solid particles which determines the rheology of semisolid AlSi6Mg2 alloy, while the external flow conditions (such as shear rate) influence the viscosity by changing the state of agglomeration. Consequently, the particle size, the packing mode and the average agglomerate size have different effect on the rheological behavior of SSMS.
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Trulsson, Martin. "Rheology and shear jamming of frictional ellipses." Journal of Fluid Mechanics 849 (June 26, 2018): 718–40. http://dx.doi.org/10.1017/jfm.2018.420.
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Understanding and predicting dense granular flows is of importance in geology and industrial applications. Still, most theoretical work has been limited to flows and packings composed of discs or spheres, a narrow subset of all possible packings. To advance our understanding of more realistic flows we here study the granular rheology of ellipses in steady-state flow with a focus on the effects of elongation and interparticle friction. We carry out novel numerical simulations of amorphous granular flows in a shear cell under confining pressure, at constant shear rate and at various aspect ratios. Both frictionless and frictional particles are considered. The various rheological curves follow the semi-empirical constitutive relations previously found for granular flows composed of discs or spheres. At the shear jamming point one finds well-defined packings, all characterised by their own set of critical parameters such as critical packing fraction, effective friction, etc. Packings composed of frictionless or almost frictionless particles are found to have a non-monotonic dependence of the macroscopic friction but a monotonic increase in packing fraction as the aspect ratio increases. For packings composed of particles with high interparticle friction the reverse is found. While frictionless packings are found to be hypostatic (except in the disc limit) frictional packings are remarkably close to the isostaticity point of having three contacts per particle. Both frictional and frictionless packings are found to have an increasing nematic ordering as the aspect ratio increases. The onset of a rolling, rather than sliding, motion between very frictional particles diminish this nematic ordering substantially. These findings put new and previously unknown bounds on the packing ratios and yield criteria for these amorphous packings at shear jamming.
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Hou, Jinghui, Yifei Ma, Zihan Zhang, Xuanhe Yang, Muhua Huang, and Chunpeng Chai. "The Relationship between Solid Content and Particle Size Ratio of Waterborne Polyurethane." Coatings 9, no. 6 (June 21, 2019): 401. http://dx.doi.org/10.3390/coatings9060401.
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A series of high solid content carboxylic acid/sulfonic acid waterborne polyurethanes was prepared by the emulsion dispersion method. The particle size and solid content were measured. By changing the particle size of the large particles to achieve different particle size ratios, high solid content waterborne polyurethanes were obtained at specific particle size ratios. When the particle size ratio was >7, 4–5 or 2–3, the aqueous polyurethane could reach a higher solid content (more than 56%). This indicated that solid content is related to particle size distribution in high solid content waterborne polyurethane. Moreover, the corresponding three-dimensional stacked models (simple cubic accumulation, face-centered cubic accumulation, cubic close packing and hexagonal closest packing) were established.
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He, Li Qun, Ping Wu, Zi Da Li, and Li Li Feng. "Dynamics for Dense Packing of Colloids." Advanced Materials Research 465 (February 2012): 248–54. http://dx.doi.org/10.4028/www.scientific.net/amr.465.248.
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Colloidal packing by evaporation is a process that particles are packed by Stokes’ forces. As particles are far from each other, interactions among them are too weak to be taken into account and it’s the Stokes’ force on free particles that is in charge of packing. However, when they are close to some extent, the force is countered by particle interactions. Here, with the aid of force balance model, we demonstrate that the further packing is achieved by all drag forces of particles in the upstream.
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Katagiri, Jun, Sukeharu Nomoto, Masahiro Kusano, and Makoto Watanabe. "Particle Size Effect on Powder Packing Properties and Molten Pool Dimensions in Laser Powder Bed Fusion Simulation." Journal of Manufacturing and Materials Processing 8, no. 2 (April 1, 2024): 71. http://dx.doi.org/10.3390/jmmp8020071.
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Various defects are produced during the laser powder bed fusion (L-PBF) process, which can affect the quality of the fabricated part. Previous studies have revealed that the defects formed are correlated with molten pool dimensions. Powder particles are thinly spread on a substrate during the L-PBF process; hence, powder packing properties should influence the molten pool dimensions. This study evaluated the influence of particle size on powder packing properties and molten pool dimensions obtained through numerical simulations. Using particles with different average diameters (Dav) of 24, 28, 32, 36, and 40 μm, a series of discrete-element method (DEM) simulations were performed. The packing fraction obtained from DEM simulations became high as Dav became small. Several particles piled up for small Dav, whereas particles spread with almost one-particle diameter thickness for large Dav. Moreover, the packing structure was inhomogeneous and sparse for large Dav. As a result of multiphysics computational fluid dynamics (CFD) simulations incorporating particles’ positions as initial solid metal volume, the molten pool width obtained was hardly dependent on the Dav and was roughly equivalent to the laser spot size used in the simulations. In contrast, the molten pool depth decreased as Dav decreased. Even if the powder bed thickness is the same, small particles can form a complex packing structure by piling up, resulting in a large specific surface area. This can lead to a complex laser reflection compared to the large particles coated with almost one-particle thickness. The complex reflection absorbs the heat generated by laser irradiation inside the powder bed formed on the substrate. As a result, the depth of the molten pool formed below the substrate is reduced for small particles.
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Sariyev, Bakytzhan, Abilkhairkhan Aldabergen, Dulat Akzhigitov, Boris Golman, and Christos Spitas. "Fabrication of Highly Compacted Green Body Using Multi-Sized Al Powder under a Centrifugal Force." Journal of Manufacturing and Materials Processing 6, no. 4 (July 22, 2022): 79. http://dx.doi.org/10.3390/jmmp6040079.
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This study investigates the application of centrifugal force for the compaction of metal powder. Previous studies using the centrifugal force for manufacturing the green bodies were focused on fine powders with narrow particle size distribution or binary mixtures. This study explores the particle packing of multi-sized powder. Aluminum alloy powder with a particle size less than 100 µm and polymer binder were admixed and compacted in the centrifugal casting with ranging magnitudes of centripetal acceleration. Three different centrifugal forces were tested: 700, 1800, and 3700 G. The microstructure of the green bodies was then observed on the SEM micrographs. The obtained green bodies had high packing densities ranging from 62 to 69%. The packing density and median particle size increase at the positions further away from the center of rotation of the centrifuge with an increase of centrifugal force. The effect of centrifugal force on the segregation of particles was investigated through the quasi-binary segregation index. The segregation phenomena was not observed at 700 G, but clear particle segregation was found at higher centrifugal forces. The increase of the centrifugal force resulted in higher segregation with finer particles moving to the inner part of the spinning mold, with a significant change in the size of particles located closer to the center of rotation. Overall, the centrifugal process was found to produce highly compacted green bodies while yielding a segregation effect due to wide particle size distribution.
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Cao, Zhe, and Ming Li. "INCLUSION OF CONTACT FRICTION FOR PARTICLE-BASED SIMULATION OF SEDIMENT TRANSPORT OVER MOBILE BED." Coastal Engineering Proceedings, no. 37 (September 1, 2023): 34. http://dx.doi.org/10.9753/icce.v37.sediment.34.
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The particle based approach, including the particle resolving method, such as CFD-DEM, e.g. Drake and Calantoni (2001), Schmeeckle (2014), and the Particle-In-Cell (PIC) method, e.g. Patankar and Joseph (2001); Finn, M. Li, and Apte (2016); Y. Li et al. (2014), has become important tool for simulation of sediment transport in recent years. The latter is advantageous in the required computing resources when large amount of particles are involved and hence is more suitable for simulation of sediment transport over mobile bed. However, unlike that in CFD-DEM, special treatment is needed in the PIC method in order to prevent overlap and over-packing of sediment particles in a computational cell. Most models so far ignore the contact friction force between particles that hinders relative movement but often is essential to maintain particles in static position, especially in the seabed where the contact forces between particles are the largest. An new friction force is proposed to simulate the particle interactions, similar to the collision used in previous studies, so that the kinetic energy driving particles motion can be effectively dissipated and over-packing can be minimised under either static or dynamic stages of the particle motion.
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Shabaev, Sergey, Sergey Ivanov, and Martel Nikita. "The Development of Theoretical Basis of Mathematical Model of Crushed Rock Particle-Particle Packing." E3S Web of Conferences 105 (2019): 01028. http://dx.doi.org/10.1051/e3sconf/201910501028.
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The existing mathematical models that predict the poly-fractional granular media packing density do not take into account their packing degree, which gives a fairly large deviation of the simulation results from the actual experimental values (up to 20-25%). To increase the reliability of prediction of the elastic modulus of crushed rocks, it is necessary to develop the mathematical model that would give more adequate values, since it is known that a change in the granular medium packing density by only 5-10% can lead to a change in the elastic modulus up to 1.5-2 times. The conditions under which smaller particles can be placed in the free space formed after packing larger particles are determined in this work on the basis of the performed computer simulation. It is established that particles of the i-th component of crushed rock can be placed in the free space formed after packing all the previous (larger) components, if the free space volume exceeds the ratio of the actual volume of the particles of the considered component to the packing density of one-dimensional particles to a degree that is exponential function of the serial number of the component.
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Alam, Parvez, and Martti Toivakka. "Fracture and Plasticity in Nano-Porous Particle-Polymer Composites." Key Engineering Materials 462-463 (January 2011): 24–29. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.24.
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A fracture mechanics algorithm, used for continuum mechanics simulations of nano-porous particle-polymer composites, is described herein. The model comprises close to a thousand ceramic particles bound together by latex polymer. These packings are generated using probabilistic methods (Monte Carlo). Pore-space arises as a function of particle shape and position coupled to the concentration and distribution of latex. Since the bridges are the weakest links in the solid state continuum, an understanding of failure behaviour is paramount for the design and optimisation of these composites. The objective of this research is to statistically characterise adhesive failure at particle-latex interfaces against cohesive failure within the latex bridges. To achieve this, a novel numerical method was developed. This method solves ordinary differential equations for vectors of force and displacement in layers through the computational packing. The model includes a scheme for non-linear elastic behaviour that evolves into a plastic flow regime. The model moreover incorporates a routine for interfacial failure between particulates and binder. Geometrical features such as solid state anfractuosity, bridge orientation, material fraction and coordination numbers are calculated from the packing output. The number of bridges straining plastically within the packing is lower than those that fracture at the interface. Fracture and failure are both related to the particle-binder coordination number. There is no evidence to suggest that decreasing the contacting sizes of binder at interfaces as well as making them thinner will lead to more plastic failure and decrease fracture. Rather, both plastic failure and fracture increase as a function of decreased contacting sizes and bulk diameters. The residual elastic modulus decreases exponentially as the number of broken connections increases.
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HERMANN, A., E. A. LANGARO, S. H. LOPES DA SILVA, and N. S. KLEIN. "Particle packing of cement and silica fume in pastes using an analytical model." Revista IBRACON de Estruturas e Materiais 9, no. 1 (February 2016): 48–65. http://dx.doi.org/10.1590/s1983-41952016000100004.
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When added to concrete in appropriate content, silica fume may provide an increase in the mechanical strength of the material due to its high pozzolanic reactivity. In addition to the chemical contribution, physical changes can also be observed in concretes with silica fume due to an improvement in the particle packing of the paste. This is a result of their small size spherical particles, which fill the voids between the larger cement grains. However, it is necessary to properly establish the cement replacement content by silica fume, because at high amounts, which exceed the volume of voids between the cement particles, silica fume can promote the loosening of these particles. Thus, instead of filling the voids and increasing the packing density, the addition of silica fume will increase the volume of voids, decreasing the solid concentration. Consequently, this will impair the properties of the concrete. The objective of this paper is to use a particle packing analytical model, the CPM (Compressible Packing Model), to verify the maximum packing density of cement and silica fume, which could be associated with the silica fume optimum content in pastes. The ideal content of silica fume in pastes, mortars and concretes is usually experimentally determined. However, a theoretical study to contrast experimental data may help understanding the behaviour of silica fume in mixes. Theoretical results show maximum amounts of silica fume in the order of 18 to 20% of the cement weight, which is high considering recommendations on literature of 15%. Nevertheless, the packing model does not consider the effect of silica fume high specific surface on the agglomeration of particles or water demand. Hence, the packing density predicted by this model cannot be used as the single parameter in determining the optimum amount of silica fume in pastes.
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Xu, Zhiwei, Michael Yu Wang, and Tianning Chen. "An Experimental Study of Particle Damping for Beams and Plates." Journal of Vibration and Acoustics 126, no. 1 (January 1, 2004): 141–48. http://dx.doi.org/10.1115/1.1640354.
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This paper describes an experimental investigation of a particle damping method for a beam and a plate. Tungsten carbide particles are embedded within longitudinal (and latitudinal) holes drilled in the structure, as a simple and passive means for vibration suppression. Unlike in traditional damping materials, mechanisms of energy dissipation of particle damping are highly nonlinear and primarily related to friction and impact phenomena. Experiments are conducted with a number of arrangements of the packed particles including different particle sizes and volumetric packing ratios. The results show that the particle damping is remarkably effective and that strong attenuations are achieved within a broad frequency range. The effects of the system parameters including particle size, packing ratio and particle material are studied by broadband and narrowband random excitations. The experimental results confirm a numerical prediction that shear friction in the longitudinal (and the latitudinal) directions is effective as the major contributing mechanism of damping in the case. Another unique feature of linear decay in free vibrations is also observed in this case of particle damping.
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Lam, David C. C. "Packing model for bimodal particle packing with aligned fibers." Journal of Materials Processing Technology 79, no. 1-3 (July 1998): 170–76. http://dx.doi.org/10.1016/s0924-0136(98)00007-7.
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KIRSH, V. A., and A. A. KIRSH. "COLLECTION OF SUBMICRON AEROSOL PARTICLES BY FILTERS COMPOSED OF NANOFIBERS." Коллоидный журнал 85, no. 1 (January 1, 2023): 38–46. http://dx.doi.org/10.31857/s0023291222600316.
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The deposition of aerosol particles from a Stokes flow in filters composed of nanofibers has been considered at Knudsen numbers Kn ∼ 1. The efficiency of particle collection by model filters with 2D and 3D structures has been determined by numerical simulation as depending on particle radius rp , filter parameters (nanofiber radius a, packing density α and filter thickness), and filtration conditions taking into account the gas slip at the fibers.It has been shown that the efficiencies of particle collection by nanofibers in model 2D and 3D filters are almost equal at the same low packing density 0.02. It has been found that the dependence of the penetration of particles on their radius at a constant velocity on the order of several centimeters per second and at Kn ∼ 1 passes through a maximum, which corresponds to particle radius rp ∼ a. The calculated sizes of the most penetrating particles agree with experimental data. The results obtained will be used when selecting aerosols for testing nanofibrous filters.
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Lebovka, N. I., M. R. Petryk, and N. V. Vygornitskii. "Percolation connectivity in deposits obtained usingcompetitive random sequential adsorption of binarydisk mixtures." Condensed Matter Physics 27, no. 1 (March 28, 2024): 13201. http://dx.doi.org/10.5488/cmp.27.13201.
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Connectedness percolation phenomena in the two-dimensional (2D) packing of binary mixtures of disks with different diameters were studied numerically. The packings were produced using random sequential adsorption (RSA) model with simultaneous deposition of disks. The ratio of the particle diameters was varied within the range D=1-10, and the selection probability of the small disks was varied within the range 0-1. A core-shell structure of the particles was assumed for the analysis of connectivity. The packing coverages in a jamming state for different components, connectivities through small, large and both types of disks, the behavior of electrical conductivity were analyzed. The observed complex effects were explained accounting for the formation of conductive "bridges" from small disks in pores between large disks.
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Luo, Lisha, Zhifu Shen, Xudong Wang, and Hongmei Gao. "Evolution of rattling particles in deviatoric shear deformation of granular material." EPJ Web of Conferences 249 (2021): 11017. http://dx.doi.org/10.1051/epjconf/202124911017.
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Granular material such as clean sand in geotechnical engineering is characterized by structured internal deformation pattern and some interesting particle arrangement patterns. This study focuses on the evolution of the fraction of rattling particles in deviator deformation until the critical state. Numerical simulations using the discrete element method reveal the presence of rattling particles (with zero or only one contact with neighbouring particles) even in a very dense packing system. The results show that the initial fraction of rattling particles depends on sample density and particle size distribution. With the increase of deviator strain, the number and volume fractions of rattling particles gradually approach a steady critical state from either a loose or a dense starting point. An effective void ratio, which is calculated by treating rattling particles as voids, can be viewed as new state parameter describing the effective packing density of sands. Besides, the rattling behaviour strongly depends on particle size distribution.
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Thiede, Tobias, Tatiana Mishurova, Sergei Evsevleev, Itziar Serrano-Munoz, Christian Gollwitzer, and Giovanni Bruno. "3D Shape Analysis of Powder for Laser Beam Melting by Synchrotron X-ray CT." Quantum Beam Science 3, no. 1 (February 19, 2019): 3. http://dx.doi.org/10.3390/qubs3010003.
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The quality of components made by laser beam melting (LBM) additive manufacturing is naturally influenced by the quality of the powder bed. A packing density <1 and porosity inside the powder particles lead to intrinsic voids in the powder bed. Since the packing density is determined by the particle size and shape distribution, the determination of these properties is of significant interest to assess the printing process. In this work, the size and shape distribution, the amount of the particle’s intrinsic porosity, as well as the packing density of micrometric powder used for LBM, have been investigated by means of synchrotron X-ray computed tomography (CT). Two different powder batches were investigated: Ti–6Al–4V produced by plasma atomization and stainless steel 316L produced by gas atomization. Plasma atomization particles were observed to be more spherical in terms of the mean anisotropy compared to particles produced by gas atomization. The two kinds of particles were comparable in size according to the equivalent diameter. The packing density was lower (i.e., the powder bed contained more voids in between particles) for the Ti–6Al–4V particles. The comparison of the tomographic results with laser diffraction, as another particle size measurement technique, proved to be in agreement.
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Duriagina, Z. A., I. A. Lemishka, V. V. Kulyk, and H. A. Hrydova. "Determination of properties of non-spherical VT20 alloy powders for modelling packing density." Metaloznavstvo ta obrobka metalìv 96, no. 4 (December 1, 2020): 56–63. http://dx.doi.org/10.15407/mom2020.04.056.
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The study of unfavorable titanium alloy powders of VT20 grades was carried out and the methods of computer analysis were applied to determine the parameters of their optimal packaging. Metallographic studies were performed on a scanning electron microscope EVO-40XVP, and elemental analysis was performed using an energy dispersion spectrometer OXFORD INCA Energy 350. Determination of particle size distribution of powders was performed using image analysis software ImageJ. The surface morphology of non-spherical particles of VT20 alloy powder was studied for three different fractions: 100 ... 160 μm, 160 ... 200 μm and 200 ... 250 μm. It is shown that the powder particles are characterized by a nonspherical shape and a small difference in size. There is a tendency according to which when the particle size of the powder of the investigated alloy decreases, their shape approaches spherical. According to the results of particle size analysis, it was found that the usual sieve analysis does not allow to fully assess the distribution of powder by fractions. It was found that for the fraction 200 ... 250 μm the dominant particles are with an average diameter of 226 μm, for the fraction 160 ... 200 μm - 177 μm and for the fraction 100 ... 160 μm - 114 μm, respectively. Thus, for the fraction of titanium powder of the BT20 brand 200 ... 250 the polydispersity is 6.4%, for the fraction 160 ... 200 - 8.3%, and for the fraction 100 ... 160 - 9.1%. It is established that the fluidity of titanium alloy powders of the BT20 brand is: for the fraction 200 ... 250 μm - 62.35 s, for the fraction 160 ... 200 μm - 65.44 s, and for the fraction 100 ... 160 - 68, 73 s. That is, the highest value of fluidity is characterized by the powder with the largest particle size. Simulation of the pre-defined volume filling was performed using the "Spheres test" program. The average radii of particles of VT20 titanium alloy powder particles and the probability of the sizes of each of fractions of powder which is necessary at filling of the set volume was calculatedthe possibility of their precipitation have been established. Based on the obtained results, the packing density of VT20 titanium alloy powders was calculated depending on their fractional composition. It is confirmed that as the particle size of the powder decreases, their packing density increases. The surface morphology of non-spherical particles of VT20 alloy powder of different fractional composition and their particle size characteristics were studied. It is shown that with decreasing fractional composition of powder fractions, their homogeneity and bulk density increase. It was found that finer fractions are characterized by poorer fluidity. The simulation results determine the optimal fractional composition of the powder to fill the pre-specified volume. It is shown that as the size of the test particles decreases, their packing density increases. Keywords: additive production, titanium, microstructure, particle size distribution, bulk density, fluidity, packing density modelingmodelling.
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Specht, Eckard. "A precise algorithm to detect voids in polydisperse circle packings." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2182 (October 2015): 20150421. http://dx.doi.org/10.1098/rspa.2015.0421.
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Computer simulations are the primary tool for studying polydisperse particle packings quanti- tatively. For the problem of packing N unequal circles in a larger container circle, nothing is known a priori about the optimal packing (i.e. the packing with the highest packing fraction). Simulations usually start from a random initial configuration with the aim to finish with a dense final packing. Unfortunately, smaller circles often get stuck in trapped positions and prevent the rest of the packing from growing larger. Hence, the knowledge of the structure of unoccupied areas or holes inside a packing is important to be able to move trapped circles into free circular places or voids . A novel algorithm is proposed for detecting such voids in two-dimensional arbitrary circle packings by a decomposition of the contact graph. Combined with a clever object jumping strategy and together with other heuristic methods like swaps and shifts, this approach increases the packing fraction ϕ significantly. Its effectiveness for jumping across the maximally random jammed barrier ( ϕ MRJ ≈0.8575 in the large- N limit) for small benchmark instances as well as for large problem sizes (up to N ≈10 3 ) is demonstrated.
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Assarsson, A., I. Nasir, M. Lundqvist, and C. Cabaleiro-Lago. "Kinetic and thermodynamic study of the interactions between human carbonic anhydrase variants and polystyrene nanoparticles of different size." RSC Advances 6, no. 42 (2016): 35868–74. http://dx.doi.org/10.1039/c6ra06175c.
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Liu, Xiang, and Rui Jie Yu. "Blast Furnace Slag Foundation Packing Grading and Compaction Characteristics Analysis." Applied Mechanics and Materials 368-370 (August 2013): 855–59. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.855.
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Through the packing particles analysis test and heavy compaction test at different depths of new system of Baotou steel finished product of the test section , analysis of the grain size distribution of slag and fly ash mixture and the content of coarse and fine particles on compaction effect are conducted , the results show that the filler embankment foundation is mainly for uniform gradation and continuous filler, when the coarse particle of the filler is 83% ～ 84% content, the compaction effect is best. Using multiple linear regression, the grain size distribution characteristics of the filler particle size equation, coarse and fine particle content and maximum dry density of the regression equation are obtained .
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Chen, Z., L. G. Gibilaro, and N. Jand. "Particle packing constraints in fluid–particle system simulation." Computers & Chemical Engineering 27, no. 5 (May 2003): 681–87. http://dx.doi.org/10.1016/s0098-1354(02)00258-2.
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Cersonsky, Rose K., Greg van Anders, Paul M. Dodd, and Sharon C. Glotzer. "Relevance of packing to colloidal self-assembly." Proceedings of the National Academy of Sciences 115, no. 7 (January 30, 2018): 1439–44. http://dx.doi.org/10.1073/pnas.1720139115.
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Since the 1920s, packing arguments have been used to rationalize crystal structures in systems ranging from atomic mixtures to colloidal crystals. Packing arguments have recently been applied to complex nanoparticle structures, where they often, but not always, work. We examine when, if ever, packing is a causal mechanism in hard particle approximations of colloidal crystals. We investigate three crystal structures composed of their ideal packing shapes. We show that, contrary to expectations, the ordering mechanism cannot be packing, even when the thermodynamically self-assembled structure is the same as that of the densest packing. We also show that the best particle shapes for hard particle colloidal crystals at any finite pressure are imperfect versions of the ideal packing shape.
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Cheng, Yun-Hong, Bao-Long Zhu, Si-Hui Yang, and Bai-Qiang Tong. "Design of Concrete Mix Proportion Based on Particle Packing Voidage and Test Research on Compressive Strength and Elastic Modulus of Concrete." Materials 14, no. 3 (January 29, 2021): 623. http://dx.doi.org/10.3390/ma14030623.
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According to the basic principle of dense packing of particles, and considering the interaction between particles, a dense packing model of granular materials in concrete was proposed. During the establishment of this model, binary particle packing tests of crushed stone and sand were carried out. The fitting analysis of the test results determines the relationship between the particle size ratio and the remaining volume fraction of the particle packing, and then the actual void fraction of the particle packing was obtained, based on which the water–binder ratio was combined to determine the amount of various materials in the concrete. The proposed concrete mix design method was used to prepare concrete, and its compressive strength and elastic modulus were tested experimentally. The test results show that the aggregate volume fraction of the prepared concrete increased, and the workability of the concrete mixture with the appropriate amount of water reducing agent meets the design requirements. When the water–binder ratio was 0.42, 0.47, or 0.52, the compressive strength of the concrete increased compared with the control concrete, and the degree of improvement in compressive strength increased with the decrease in water–binder ratio; when the water-binder ratio was 0.42, 0.47, or 0.52, the static elastic modulus of the concrete increased compared with the control concrete, and the degree of improvement in elastic modulus also increased with the decrease in water–binder ratio. The elastic modulus and compressive strength of the prepared concrete have a positive correlation. Findings show that the concrete mix design method proposed by this research is feasible and advanced in a sense.