Modeling Ductile/Brittle Behavior in Polymeric Microlaminates: Effect of Volume Fraction

2006 ◽  
Vol 977 ◽  
Author(s):  
Rajdeep Sharma ◽  
Mary C. Boyce ◽  
Simona Socrate
Keyword(s):  
Volume Fraction ◽  
Micromechanical Model ◽  
Three Dimensional ◽  
Failure Criteria ◽  
Two Phase ◽  
Shear Yielding ◽  
Deformation And Failure ◽  
Brittle Behavior ◽  
Brittle Layers ◽  
Mechanisms Of Deformation

AbstractIn this work we present a micromechanical model for two-phase ductile/brittle laminates that captures the macroscopic behavior, as well as the underlying micro-mechanisms of deformation and failure, in particular the synergy between the inelastic deformation mechanisms of crazing and shear yielding. The finite element implementation of our model considers a three-dimensional representative volume element (RVE), and incorporates continuum-based physics-inspired descriptions of shear yielding and crazing, along with failure criteria for the ductile and brittle layers. The interface between the ductile and brittle layers is assumed to be perfectly bonded. The model successfully explains the volume fraction effect on the micro and macromechanics of ductile/brittle microlaminates subjected to uniaxial tension.

Droplet Formation in a Microchannel T-Junction With Different Step Structure Position

2020 ◽  
Vol 143 (7) ◽  
Author(s):  
Mohammad Yaghoub Abdollahzadeh Jamalabadi ◽  
Rasoul Kazemi ◽  
Mohammad Ghalandari
Keyword(s):  
Nusselt Number ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Droplet Formation ◽  
Continuous Phase ◽  
Flow Path ◽  
The Other ◽  
Two Phase ◽  
Fluid Behavior ◽  
Discrete Phase

Abstract In this study, numerical simulation of formation of droplet within T-shaped microchannel is investigated. Three-dimensional, transient and two-phase numerical solution for four different microchannels with different stepping positions in the flow path was performed. Various parameters such as volume fraction, Nusselt number, pressure, Reynolds number, and temperature are discussed. The results show that the location of stepped barriers in the flow path affects the process of droplet formation, its number and size in the microchannel and should be considered as an important factor in determining the fluid behavior in the microchannel. It was observed that by placing half of the step at the entrance and the other half after the entrance, the continuous phase (S3 mode) was formed in 37.5 s compared to the other modes. The droplets were also smaller in size and more in numbers. It was also observed that the maximum value for the Nusselt number was obtained for the S2 mode where the step was located just above the discrete-phase entrance. In addition, the pressure at the inlet was higher and the flow velocity increased after the step and its pressure decreased, and continued to decrease due to frictional path.

Vortex Simulation for Behavior of Solid Particles Falling in Air

2011 ◽  
Author(s):  
Hisanori Yagami ◽  
Tomomi Uchiyama
Keyword(s):  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Air Flow ◽  
Three Dimensional ◽  
Particle Diameter ◽  
Vortex Method ◽  
Solid Particles ◽  
Particle Volume ◽  
Two Phase ◽  
Spherical Region

The behavior of small solid particles falling in an unbounded air is simulated. The particles, initially arranged within a spherical region in a quiescent air, are made to fall, and their fall induces the air flow around them, resulting in the gas-particle two-phase flow. The particle diameter and density are 1 mm and 7.7 kg/m3 respectively. A three-dimensional vortex method proposed by one of the authors is applied. The simulation demonstrates that the particles are accelerated by the induced downward air flow just after the commencement of their fall. It also highlights that the particles are whirled up by a vortex ring produced around the downward air flow after the acceleration. The effect of the particle volume fraction at the commencement of the fall is also explored.

The Effect of Microstructural Morphologies on the Effective Electromechanical Properties of Piezoelectric Particle Composites

2012 ◽  
Author(s):  
Vahid Tajeddini ◽  
Chien-hong Lin ◽  
Anastasia Muliana ◽  
Martin Lévesque
Keyword(s):  
Mechanical Properties ◽  
Elastic Moduli ◽  
Volume Fraction ◽  
Micromechanical Model ◽  
Three Dimensional ◽  
Particle Sizes ◽  
Reinforced Composites ◽  
Electromechanical Properties ◽  
Particle Volume ◽  
Self Consistent

This study introduces a micromechanical model that incorporates detailed microstructures for analyzing the effective electro-mechanical properties, such as piezoelectric and permittivity constants as well as elastic moduli, of piezoelectric particle reinforced composites. The studied composites consist of polarized spherical piezoelectric particles dispersed into a continuous and elastic polymeric matrix. A micromechanical model generated using three-dimensional (3D) continuum elements within a finite element (FE) framework. For each volume fraction (VF) of particles, realization with different particle sizes and arrangements were generated in order to represent microstructures of a particle composite. We examined the effects of microstructural morphologies, such as particle sizes and distributions, and particle volume fractions on the overall effective electro-mechanical properties of the active composites. The overall electro-mechanical properties determined from the present micromechanical model were compared to those generated using the Mori-Tanaka, self-consistent, and simplified unit-cell micromechanical models.

The 3-D Finite Element Analysis on Elastic-Plastic Micromechanical Response of the Particle Volume Fraction

2019 ◽  
Vol 962 ◽  
pp. 210-217
Author(s):  
Yong Ming Guo ◽  
Nozomi Fukae
Keyword(s):  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Three Dimensional ◽  
Particle Volume ◽  
Two Phase ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Microstructural Parameters ◽  
Commercial Software Package ◽  
Properties Of Materials

It is well known that the properties of materials are a function of their microstructural parameters. The FEM is a good selection for studies of three-dimensional microstructure-property relationships. In this research, the elastic-plastic micromechanical response of the particle volume fraction of two-phase materials have been calculated using a commercial software package of the FEM, some new knowledges on the microstructure-property relationships have obtained.

Numerical Analysis of Erosive Wear on the Guide Vanes of a Francis Turbine

2015 ◽  
Vol 741 ◽  
pp. 531-535
Author(s):  
Hong Ming Zhang ◽  
Li Xiang Zhang
Keyword(s):  
Numerical Analysis ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Erosive Wear ◽  
Francis Turbine ◽  
Two Phase ◽  
Guide Vanes ◽  
Flow Equations ◽  
Sand Erosion ◽  
Volume Method

The paper presents the numerical analysis of erosive wear on the guide vanes of a Francis turbine using CFD code. The 3-D turbulent particulate-liquid two-phase flow equations are employed in this study. The computing domain is discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The finite volume method is used to solve the governing equations and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that the volume fraction of sand at the top of the guide vanes is higher than others and the maximum of volume fraction of sand is at same location with the maximum of sand erosion rate density. The erosive wear is more serious at the top of the guide vanes.

Three-Dimensional Numerical Simulation of Convective Melting of Solid Particles in a Fluid

1999 ◽  
Author(s):  
Y. L. Hao ◽  
Y.-X. Tao
Keyword(s):  
Volume Fraction ◽  
Solid Phase ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Phase Changes ◽  
Solid Particles ◽  
Preliminary Calculation ◽  
Two Phase ◽  
Closed Set ◽  
Gravity Effects

Abstract A physical model of two-phase flow and heat-mass transfer with the phase changes based on the theory of interacting continua is proposed. All terms in the conservation equations are analyzed and the constitutive equations are presented. A closed set of governing equations describing the convective melting of solid particles in a fluid is obtained. The numerical method is developed for the solution of velocity, temperature, and volume fraction of solid phase for the three-dimensional melting in a rectangular cross-section channel. Preliminary calculation, including gravity effects, shows that the result is reasonable. This study provides a basis for the theoretical and experimental investigation of convective melting of solid particles in a fluid.

scholarly journals Simulation of Boiling Flow Experiments Close to CHF with the Neptune_CFD Code

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Boštjan Končar ◽  
Borut Mavko
Keyword(s):  
Volume Fraction ◽  
Flow Boiling ◽  
Three Dimensional ◽  
Heated Wall ◽  
Wall Region ◽  
Two Phase ◽  
Subcooled Flow Boiling ◽  
Boiling Flow ◽  
Flow Experiments ◽  
Near Wall

A three-dimensional two-fluid code Neptune_CFD has been validated against the Arizona State University (ASU) and DEBORA boiling flow experiments. Two-phase flow processes in the subcooled flow boiling regime have been studied on ASU experiments. Within this scope a new wall function has been implemented in the Neptune_CFD code aiming to improve the prediction of flow parameters in the near-wall region. The capability of the code to predict the boiling flow regime close to critical heat flux (CHF) conditions has been verified on selected DEBORA experiments. To predict the onset of CHF regime, a simplified model based on the near-wall values of gas volume fraction was used. The results have shown that the code is able to predict the wall temperature increase and the sharp void fraction peak near the heated wall, which are characteristic phenomena for CHF conditions.

Extrinsic viscous anisotropy in two-phase aggregates, fabric parametrisation and application to mantle convection

2020 ◽  
Author(s):  
Albert de Montserrat Navarro ◽  
Manuele Faccenda
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Phase ◽  
Mantle Dynamics ◽  
Mineral Phases ◽  
Viscosity Contrast ◽  
The Matrix ◽  
Order Of Magnitude ◽  
Convection Patterns ◽  
Strong Inclusion

<p>Earth's mantle rocks are poly-aggregates where different mineral phases coexist.  These rocks may often be approximated as two-phase aggregates with a dominant phase and less abundant one (e.g. bridgmanite-ferropericlase aggregates in the lower mantle). Severe shearing of these rocks leads to a non-homogeneous partitioning of the strain between the different phases. The resulting bulk rock is mechanically not isotropic, and the elastic and the viscous tensor depend on the volume fraction and viscosity contrast between the mineral phases and the fabric.</p><p>Here we employ three-dimensional mechanical models to reproduce and parametrise fabrics typical of mantle rocks and quantify the evolution of the viscous tensor. These fabrics are produced by shearing a mechanically heterogeneous medium comprised by randomly distributed isotropic inclusions embedded in: i) a weak inclusion-strong matrix aggregate where strain is mainly accommodated by the weak phase, that flattens and yields a penetrative foliation; and, ii) a strong inclusion-weak matrix where strain is mainly accommodated by the matrix, in this case, the strong phase deforms primarily parallel to the direction of the flow, producing cigar-shaped inclusions.</p><p>Finally, we combine the fabric parametrisation of a two-phase aggregate with the Differential Effective Medium (DEM) theory to study the evolution of the viscous tensor and its effects in mantle dynamics. The results of two-dimensional models of thermal convection show that a viscosity contrast of one order of magnitude between the two mineral phases is enough to deflect mantle plumes and produce convection patterns that differ considerably from the ideal isotropic media.</p>

Intersect distributions of a `dead leaves' model with spherical primary grains

2005 ◽  
Vol 38 (3) ◽  
pp. 520-527 ◽  
Author(s):  
Wilfried Gille
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Length Distribution ◽  
Hard Core ◽  
Spherical Particles ◽  
Characteristic Functions ◽  
Phase System ◽  
Two Phase ◽  
Linear Integration ◽  
Dead Leaves Model

This article analyses a tightly packed random two-phase system possessing spherical particles having the volume fraction of 1/8. For a three-dimensional hard-core `dead leaves' model of spheres of constant diameter, the chord length distribution density of typical chords m i of the connected phase (outside the hard particles) is investigated. The calculation starts from the second derivative of the small-angle scattering correlation function of the model and applies characteristic functions. The result fulfills Rosiwal's linear integration principle.

scholarly journals A Three-Dimensional Random Walk Algorithm for Estimating the Chloride Diffusivity of Concrete

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5700
Author(s):  
Hua Rong ◽  
Cong-Yan Zhang ◽  
Jian-Jun Zheng ◽  
Jian Zhang ◽  
Xin-Zhu Zhou ◽  
...  
Keyword(s):  
Random Walk ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Mean Square Displacement ◽  
Computational Time ◽  
Aggregate Model ◽  
Two Phase ◽  
Chloride Diffusivity ◽  
Random Walk Algorithm ◽  
Walk Algorithm

The chloride diffusivity of concrete is an important parameter for assessing the long-term durability of coastal concrete structures. The purpose of this paper is to present a three-dimensional random walk algorithm (RWA) for estimating the chloride diffusivity of concrete. By analyzing the size distribution of aggregates, the equivalent interfacial transition zone (ITZ) thickness is derived in an analytical manner. Each aggregate is combined with the surrounding ITZ to construct an equivalent aggregate model (EAM) and the chloride diffusivity is formulated. It is found that the equivalent ITZ thickness decreases with the increase of practical ITZ thickness and aggregate volume fraction. The aggregate gradation influences the equivalent ITZ thickness to a certain extent. The relative chloride diffusivity of the equivalent aggregate is almost directly and inversely proportional to the equivalent ITZ thickness and the aggregate radius, respectively. The numerical results show that, when the EAM is adopted, the computational time is greatly reduced. With the EAM, concrete can be modeled as a two-phase material and the chloride diffusivity is estimated by applying the RWA. It is shown that, with the increase of mean square displacement and number of Brownian particles, the average chloride diffusivity of concrete approaches a stable value. Finally, through comparison with experimental data, the validation of the RWA is preliminarily verified.

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