Numerical Simulation of Motion Rules of Coarse Aggregates in the Compaction Process

2015 ◽  
Vol 44 (2) ◽  
pp. 20150228
Author(s):  
Ying Gao ◽  
Weidong Liu ◽  
Hanguang Li ◽  
Xiongwei Dai
Keyword(s):  
Numerical Simulation ◽  
Compaction Process ◽  
Coarse Aggregates

Simulation Study of Granular Compaction Dynamics under Vertical Tapping

2007 ◽  
Vol 555 ◽  
pp. 107-112 ◽  
Author(s):  
D. Arsenović ◽  
S.B. Vrhovac ◽  
Z.M. Jakšić ◽  
Lj. Budinski-Petković ◽  
A. Belić
Keyword(s):  
Numerical Simulation ◽  
Molecular Dynamics ◽  
Friction Coefficient ◽  
Simulation Study ◽  
Material Properties ◽  
Two Dimensions ◽  
Second Phase ◽  
Hard Disks ◽  
Compaction Process ◽  
Granular Compaction

We study by numerical simulation the compaction dynamics of frictional hard disks in two dimensions, subjected to vertical shaking. Shaking is modeled by a series of vertical expansions of the disk packing, followed by dynamical recompression of the assembly under the action of gravity. The second phase of the shake cycle is based on an efficient event−driven molecular−dynamics algorithm. We analyze the compaction dynamics for various values of friction coefficient and coefficient of normal restitution. We find that the time evolution of the density is described by ρ(t)=ρ∞ − ρEα[−(t/τ)α], where Eα denotes the Mittag−Leffler function of order 0<α<1. The parameter τ is found to decay with tapping intensity Γ according to a power law τ ∝ Γ−γ , where parameter γ is almost independent of the material properties of grains. Also, an expression for the grain mobility during compaction process has been obtained.

Numerical Simulation of the Shock Compaction of W/Cu Powders

2011 ◽  
Vol 673 ◽  
pp. 113-118 ◽  
Author(s):  
Kai Da Dai ◽  
Peng Wan Chen
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Micromechanical Model ◽  
Rigid Wall ◽  
Metal Powders ◽  
Simulation Approach ◽  
Particle Deformation ◽  
Compaction Process ◽  
Lagrange Formulation ◽  
Shock Compaction

A numerical simulation approach is used to study the deformation and temperature distribution of W/Cu powders under shock compaction. A two-dimensional micromechanical model is employed where only a few particles are considered. The simulation is performed using plane strain element and Lagrange formulation. Shock compaction is achieved by bringing in the W/Cu powders an intense compression wave using a high-velocity rigid wall. The effects of compact velocity, particle size and friction on the particle deformation and temperature distribution are discussed based on the results of simulations. The study provides a detailed understanding of the micromechanical behavior of metal powders during shock compaction process.

scholarly journals EXPERIMENTAL AND NUMERICAL INVESTIGATION OF SAND COMPRESSION PECULIARITIES

2013 ◽  
Vol 19 (1) ◽  
pp. 78-85 ◽  
Author(s):  
Šarunas Skuodis ◽  
Arnoldas Norkus ◽  
Liudas Tumonis ◽  
Jonas Amšiejus ◽  
Ceslovas Aksamitauskas
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Numerical Modeling ◽  
Compression Test ◽  
Void Ratio ◽  
Vertical Stress ◽  
Compaction Process ◽  
Compression Properties ◽  
Sample Compression ◽  
The Baltic

Investigation of the compression properties of Klaipėda sand by oedometric testing and numerical modeling is presented. Klaipėda sand is characteristic of the Baltic seashore region sand. Experimental investigation was performed with fraction corresponding to diameter variation bounds of 0.6 and 0.425 mm. Compression test was realized with initial maximal void ratio (e 0 = 0.800) of sand. Employed vertical stress ramp value is 800.0 kPa/min, maximum loading σmax = 400.0 kPa. Applying loading within the range of 50.0 to 120.0, two vertical stress jumps have been identified. A rubber sample compression test has been performed aiming to deny an assumption, that vertical stress jumps are influenced by device construction. Experiment viewed that not any vertical stress jumps have been recognized. Numerical simulation yielded exactly the same two vertical stress jumps found by compression with oedometer. It proves that the nature of rearrangement of sand grains has been properly reflected by modeling compaction process by DEM. Sand compaction velocity is higher versus applied vertical stress ramp. This is the reason for appearing of the vertical stress jumps. Numerical simulation viewed that location of the largest compression in oedometer is at the top of the sample.

Aggregate Degradation Characteristics of Stone Mastic Asphalt Mixtures

2013 ◽  
Vol 65 (3) ◽  
Author(s):  
Mohd. Rosli Hainin ◽  
Norliza Mohd Akhir ◽  
Ramadhansyah Putra Jaya ◽  
Nur Izzi Md. Yusoff ◽  
Haryati Yaacob ◽  
...  
Keyword(s):  
Coarse Aggregate ◽  
Asphalt Mixtures ◽  
Compaction Process ◽  
Traffic Loading ◽  
Coarse Aggregates ◽  
Mastic Asphalt ◽  
Superpave Gyratory Compactor ◽  
Stone Mastic Asphalt ◽  
The Relationship ◽  
Compaction Method

Stone Mastic Asphalt (SMA) mixtures are designed to have a high coarse aggregate content and stone-on-stone contact, which results in more stress on the coarse aggregates during compaction and traffic loading. As a result, aggregates tend to break down more in SMA mixtures than in conventional dense graded mixtures. Aggregate degradation during compaction and traffic loading may cause changes in the original gradation and thus may also affect the volumetric parameters of SMA mixtures. Therefore, this  study was conducted to determine the degree of aggregate degradation in SMA mixtures due to the compaction process. Aggregates of two Nominal Maximum Aggregates Sizes (NMAS), designated as SMA14 and SMA20, were compacted using 50 blows of the Marshall Hammer and 100 gyrations of the Superpave Gyratory Compactor (SGC). The verified samples were then prepared and extracted using the Centrifuge Method. The relationship between aggregate degradation and influencing factors, such as compaction effort and volumetric properties were investigated. Aggregate degradation by the Marshall Hammer was found to be significantly higher than degradation by the SGC. Voids in the mineral aggregate (VMA) of either compaction method decrease or are almost the same when aggregate degradation is not significant. SGC method can be selected to represent the field roller that results in a similar trend of aggregate degradation.

Numerical Simulation of Underwater Explosive Compaction Process for Compaction of Tungsten Powder

2007 ◽  
Vol 566 ◽  
pp. 77-82 ◽  
Author(s):  
Mehdi Zohoor ◽  
A. Mehdipoor
Keyword(s):  
Numerical Simulation ◽  
Tungsten Powder ◽  
Research Work ◽  
Theoretical Method ◽  
Amorphous Powder ◽  
Die Design ◽  
Compaction Process ◽  
Explosive Compaction ◽  
Mean Grain Size ◽  
Relative Hardness

Underwater explosive compaction is a modified explosive compaction process that is used for manufacturing of parts by compaction of hard powders such as tungsten powder. In the present research work, equation of state (EOS) for tungsten powder was determined by a theoretical method and numerical simulation of the underwater explosive compaction process for tungsten powder was done using LS-DYNA program. The simulation results were utilized for the optimization of die design setups, which were used in our experimental test. Several experiments for compaction of tungsten amorphous powder with a mean grain size about 5 microns were performed using C4 explosive with a detonation velocity about 8.2 km/s. The hardness and density of consolidated samples were determined. The fragmented surfaces of samples were analyzed by scanning electron microscope (SEM). The experimental results indicated the usefulness of computer simulation for optimization of die design and the process parameters. In addition, the results indicated that the tungsten parts without cracks and with a high relative hardness and density could be obtained by underwater explosive compaction method.

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