Ultrasonic Attenuation of Gas-Solid Flow Pneumatic Conveying Fly Ash

2013 ◽  
Vol 437 ◽  
pp. 335-338
Author(s):  
Guang Bin Duan ◽  
Hong Li Pan ◽  
Yong Wang ◽  
Zong Ming Liu
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Volume Fraction ◽  
Ultrasonic Attenuation ◽  
Particle Volume Fraction ◽  
Ultrasonic Frequency ◽  
Pneumatic Conveying ◽  
Particle Volume ◽  
Attenuation Coefficients ◽  
Volume Fractions

In order to set solid particle phase distributed uniformly in the whole detection space， the McClements model and Bouguer -Lambert -Beer law model were applied to formulate the ultrasonic attenuation properties of gas-solid flow for pneumatic conveying fly ash. The theoretical relation between the ultrasonic attenuation coefficients and the flow parameters of gas/ solids two-phase flow was established. By numerical simulations, the alteration laws of the ultrasonic attenuation coefficients with particle volume fraction， ultrasonic frequency and particle size were analyzed. The results show that the higher the ultrasonic frequency was, the greater the attenuation coefficients were. The ultrasonic attenuation coefficients linearly increased with the increasing of the solid particles volume fraction. If some fixed frequency was chosen， the slopes of attenuation -volume fractions curves can be confirmed by just testing ultrasonic attenuation coefficients under two volume fractions. So that testing of particle volume fraction corresponding to arbitrarily ultrasonic attenuation coefficients can be achieved. If the fly ash particle sizes were in the domain of 10 -200 μm with the same volume fraction， the ultrasonic attenuation coefficients monotonically decreased with the increasing of the particle size. But if the fly ash particle size was higher than 200 μm， the ultrasonic attenuation coefficients were no longer sensitive to the solids particle size.

scholarly journals Meso-Simulation and Experimental Research on the Mechanical Behavior of an Energetic Explosive

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 64
Author(s):  
Qinxue Pan ◽  
Shuangyang Li ◽  
Yang Liu ◽  
Xiaoyu Xu ◽  
Meile Chang ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Volume Fraction ◽  
Ultrasonic Attenuation ◽  
Particle Volume Fraction ◽  
Effective Elastic Modulus ◽  
Testing System ◽  
Ultrasonic Frequency ◽  
Particle Volume ◽  
Element Analysis ◽  
Polymer Bonded Explosives

This study establishes a model for polymer-bonded explosives (PBX) using Digimat-FE. The model identifies the relationship between the material’s effective elastic modulus and the explosive particle volume fraction, shape and gradation, and porosity, as well as other factors. Further, finite element analysis of the stress distribution of the PBX composite material is performed, and the mathematical models between the ultrasonic attenuation coefficient, particle volume fraction, and ultrasonic frequency are established. Finally, an efficient ultrasonic nondestructive testing system is designed to determine the stress distribution and fine crack groups in the material. Experimental results indicate that the relative error of stress detection is within 15%, which meets the requirements of engineering applications.

scholarly journals Improved Heat Transfer in Guar Gel Composites Reinforced with Randomly Distributed Glass Microspheres

2021 ◽  
Author(s):  
Ruifeng CAO ◽  
Taotao WANG ◽  
Yuxuan ZHANG ◽  
Hui WANG
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Particle Size ◽  
Composite Materials ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Glass Microspheres ◽  
Particle Volume ◽  
Number Of Particles

Improved heat transfer in composites consisting of guar gel matrix and randomly distributed glass microspheres is extensively studied to predict the effective thermal conductivity of composites using the finite element method. In the study, the proper and probabilistic three-dimensional random distribution of microspheres in the continuous matrix is automatically generated by a simple and efficient random sequential adsorption algorithm which is developed by considering the correlation of three factors including particle size, number of particles, and particle volume fraction controlling the geometric configuration of random packing. Then the dependences of the effective thermal conductivity of composite materials on some important factors are investigated numerically, including the particle volume fraction, the particle spatial distribution, the number of particles, the nonuniformity of particle size, the particle dispersion morphology and the thermal conductivity contrast between particle and matrix. The related numerical results are compared with theoretical predictions and available experimental results to assess the validity of the numerical model. These results can provide good guidance for the design of advanced microsphere reinforced composite materials.

Multi-Scale Approach for Nonhomogeneous Microstructural Effects on Damage in Particulate Composites

2003 ◽  
Author(s):  
W. M. Cho ◽  
Y. W. Kwon ◽  
C. T. Liu
Keyword(s):  
Volume Fraction ◽  
Global Analysis ◽  
Particle Volume Fraction ◽  
Crack Tip ◽  
Particulate Composites ◽  
Local Analysis ◽  
Particle Volume ◽  
Damage Initiation ◽  
Volume Fractions ◽  
Multi Scale

This study investigated the effects of random and non-uniform particle distributions on the damage initiation and growth in particulate composites. Numerical specimens with either no crack or an existing crack were examined. For the cases with no crack, the effect of sizes of the representative area for non-uniform particle volume fractions was studied on the overall stress-strain curves and the results were compared with that of the specimen with uniform particle volume fractions. Other studies considered cracked specimens, either single edge crack or a center crack. The global-local approach was used along with multi-scale technique. The global analysis determined the deformations around the crack tip. Then, the local analysis evaluated the damage progress at the crack tip using the solution of the global analysis as boundary conditions. The results showed non-uniformed particle volume fractions in particulate composites caused the crack growth at lower applied loads than the uniform particle volume fraction. Statistical data were also plotted for the non-uniform particle volume fraction cases.

3D Micro-Structural Modeling of Vibration Characteristics of Smart Particle-Reinforced Metal-Matrix Composite Beams

2019 ◽  
Vol 19 (07) ◽  
pp. 1950078
Author(s):  
Recep Ekici ◽  
Vahdet Mesut Abaci ◽  
J. N. Reddy
Keyword(s):  
Particle Size ◽  
Metal Matrix Composite ◽  
Metal Matrix ◽  
Vibration Amplitude ◽  
Natural Frequencies ◽  
Particle Distribution ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Particle Volume ◽  
Random Particle

In this study, the effects of micro-structural parameters such as particle volume fraction, size and random distribution of Al 6061/SiC particulate metal-matrix composite (MMC) beams on free vibration response and the active vibration control are investigated. For this purpose, numerical particle-reinforced MMC (PRMMC) beam specimens were modeled with 3D finite elements, and the cubic-shaped reinforcing SiC particles were randomly distributed in Al 6061 metal matrix similar to an actual micro-structure. The particle size and especially volume fraction play an important role on the natural frequencies of the smart PRMMCs although they have no effect on the mode shapes. The random particle distribution has minor effect on the natural frequencies of the smart PRMMCs. With the increase of the feedback control gain, both the vibration amplitude and the suppression time are reduced reasonably. Increasing the particle volume fraction induces an important reduction in the damping time and the vibration amplitude for both the controlled and uncontrolled damped vibrations. Finally, increasing the particle size decreases the vibration suppression capacity and increases the vibration amplitude and time slightly. Random particle distribution had no obvious effect on the uncontrolled and controlled vibrations.

Disordered Spheres with Extensive Overlap in Projection: Image Simulation and Analysis

2011 ◽  
Vol 17 (6) ◽  
pp. 872-878 ◽  
Author(s):  
Christopher D. Chan ◽  
Michelle E. Seitz ◽  
Karen I. Winey
Keyword(s):  
Particle Size ◽  
Critical Thickness ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Spherical Particles ◽  
Specimen Thickness ◽  
Number Density ◽  
Particle Volume ◽  
Transmission Electron ◽  
Projection Image

AbstractThis article simulates highly overlapped projections of spherical particles that are distributed randomly in space. The size and number of the features in the projections are examined as well as how these features change with particle size and concentration. First, there are discernable features in projection even when particles overlap extensively, and the size of these discernable features is the expected size of an individual particle. Second, the number of features increases with specimen thickness at a rate of t0.543 when the specimen thickness is below a critical value and becomes independent of specimen thickness at higher thicknesses. A criterion is established for the critical thickness based on particle size and particle volume fraction. When the specimen thickness is known and smaller than the critical thickness, a single representative transmission electron microscopy (TEM) (or scanning TEM) image exhibiting extensive particle overlap can be used to determine the size and number density of the spherical particles.

Physical and mechanical properties of stir-casting processed AA2024/B4Cp composites

2014 ◽  
Vol 21 (4) ◽  
pp. 505-515 ◽  
Author(s):  
Aykut Canakci ◽  
Fazli Arslan ◽  
Temel Varol
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Tensile Strength ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Stir Casting ◽  
Particle Volume ◽  
Electron Microscopic ◽  
Particle Content ◽  
Casting Technique

AbstractIn this study, metal matrix composites of an aluminum alloy (AA2024) and B4C particles with volume fractions 3, 5, 7, and 10 vol% and with sizes 29 and 71 μm were produced using stir-casting technique. The effects of B4C particle content and size of boron carbide on the mechanical properties of the composites such as hardness, 0.2% yield strength, tensile strength, and fracture were investigated. Furthermore, the relation between particle content, microstructure, and particle distribution has been investigated. The hardness of the composites increased with increasing particle volume fraction and with decreasing particle size, although the tensile strength of the composites decreased with increasing particle volume fraction and with decreasing particle size. Scanning electron microscopic observations of the microstructures revealed that dispersion of the coarser sizes of B4C particles was more uniform while the finer particles led to agglomeration of the particles and porosity.

Finite Element Analysis about Effects of Particle Size on Deformation Behavior of Particle Reinforced Metal Matrix Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1263-1266
Author(s):  
Yi Wu Yan ◽  
Lin Geng ◽  
Ai Bin Li ◽  
Guo Hua Fan
Keyword(s):  
Particle Size ◽  
Finite Element ◽  
Metal Matrix Composites ◽  
Deformation Behavior ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Matrix Composites ◽  
Particle Volume ◽  
Element Analysis

By incorporating the Taylor-based nonlocal theory of plasticity, the finite element method (FEM) is applied to investigate the effect of particle size on the deformation behavior of the metal matrix composites. In the simulation, the two-dimensional plane strain and random distribution multi-particles model are used. It is shown that, at a fixed particle volume fraction, there is a close relationship between the particle size and the deformation behavior of the composites. The yield strength and plastic work hardening rate of the composites increase with decreasing particle size. The predicted stress-strain behaviors of the composites are qualitative agreement with the experimental results.

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