Numerical Study of Damage Growth in Particulate Composites

1999 ◽  
Vol 121 (4) ◽  
pp. 476-482 ◽  
Author(s):  
Y. W. Kwon ◽  
C. T. Liu
Keyword(s):  
Cell Model ◽  
Numerical Study ◽  
Matrix Material ◽  
Three Dimensional ◽  
Crack Tip ◽  
Particulate Composite ◽  
Crack Size ◽  
Particulate Composites ◽  
Specimen Thickness ◽  
Damage Initiation

A numerical study was conducted to simulate and predict damage initiation and growth around the crack tip crack tip in particulate composite specimens made of hard particles embedded in a soft rubber-like matrix material. Therefore, damage evolution in the matrix material around crack tips was investigated. The progressive damage was modeled using a micro/macro-approach which combined two levels of analyses like the micro-level and the macro-level analyses. Damage description was undertaken at the microlevel using a simplified three-dimensional unit-cell model and an isotropic continuum damage theory. The numerical study examined both him and thick specimens with a short or long edge crack to understand the effects of specimen thickness and crack size on the damage initiation, growth, and saturation. Numerical results were compared with experimental data.

The Estimation of Micro-Crack Behavior in Polymer Particulate Composite with Soft Interphase

2012 ◽  
Vol 482-484 ◽  
pp. 1660-1663 ◽  
Author(s):  
Zdeněk Majer ◽  
Luboš Náhlík ◽  
Pavel Hutař
Keyword(s):  
Material Properties ◽  
Numerical Study ◽  
Matrix Material ◽  
Particulate Composite ◽  
Particulate Composites ◽  
Linear Matrix ◽  
Crack Behavior ◽  
Crack Propagation Direction ◽  
Commercial Code ◽  
Three Phase

The presented paper is focused on the numerical study of fracture behavior of polymer particulate composites. The polymer particulate composite is modeled as a three-phase continuum. Together with particles and matrix is considered an interphase. The interphase is created on particle-matrix interface. Non-linear matrix material properties were experimentally determined and used in calculations. The main aim is to estimate micro-crack propagation direction for the variety of matrix and interphase material properties. The results are obtained using the finite element commercial code ANSYS.

Effective Stiffness of a Debonded Particle in Particulate Composites

2007 ◽  
Vol 334-335 ◽  
pp. 33-36 ◽  
Author(s):  
Akihiro Wada ◽  
Yusuke Nagata ◽  
Shi Nya Motogi
Keyword(s):  
Three Dimensional ◽  
Particulate Composite ◽  
Spherical Particles ◽  
Particulate Composites ◽  
Particle Volume ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Load Carrying ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this study, partially debonded spherical particles in a particulate composite are analyzed by three-dimensional finite element method to investigate their load carrying capacities, and the way to replace a debonded particle with an equivalent inclusion is examined. The variation in Young’s modulus and Poisson’s ratio of a composite with the debonded angle was evaluated for different particle arrangements and particle volume fractions, which in turn compared with the results derived from the equivalent inclusion method. Consequently, it was found that by replacing a debonded particle with an equivalent orthotropic one, the macroscopic behavior of the damaged composite could be reproduced so long as the interaction between neighboring particles is negligible.

scholarly journals An optimised GAS-pharyngeal cell biofilm model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Heema K. N. Vyas ◽  
Jason D. McArthur ◽  
Martina L. Sanderson-Smith
Keyword(s):  
Crystal Violet ◽  
Biofilm Formation ◽  
Cell Model ◽  
Matrix Material ◽  
Three Dimensional ◽  
Growth Period ◽  
Optimal Growth ◽  
Abiotic Surfaces

AbstractGroup A Streptococcus (GAS) causes 700 million infections and accounts for half a million deaths per year. Biofilm formation has been implicated in both pharyngeal and dermal GAS infections. In vitro, plate-based assays have shown that several GAS M-types form biofilms, and multiple GAS virulence factors have been linked to biofilm formation. Although the contributions of these plate-based studies have been valuable, most have failed to mimic the host environment, with many studies utilising abiotic surfaces. GAS is a human specific pathogen, and colonisation and subsequent biofilm formation is likely facilitated by distinct interactions with host tissue surfaces. As such, a host cell-GAS model has been optimised to support and grow GAS biofilms of a variety of GAS M-types. Improvements and adjustments to the crystal violet biofilm biomass assay have also been tailored to reproducibly detect delicate GAS biofilms. We propose 72 h as an optimal growth period for yielding detectable biofilm biomass. GAS biofilms formed are robust and durable, and can be reproducibly assessed via staining/washing intensive assays such as crystal violet with the aid of methanol fixation prior to staining. Lastly, SEM imaging of GAS biofilms formed by this model revealed GAS cocci chains arranged into three-dimensional aggregated structures with EPS matrix material. Taken together, we outline an efficacious GAS biofilm pharyngeal cell model that can support long-term GAS biofilm formation, with biofilms formed closely resembling those seen in vivo.

Damage Study in Notched Particulate Composite Specimens Under Non-Uniform Strain Loading

1999 ◽  
Author(s):  
Y. W. Kwon ◽  
C. T. Liu
Keyword(s):  
Numerical Technique ◽  
Matrix Material ◽  
Damage Model ◽  
Particulate Composite ◽  
Crack Size ◽  
Initial Crack ◽  
Reinforced Composite ◽  
Varying Length ◽  
Particle Reinforced Composite ◽  
Circular Notch

Abstract This paper studied crack initiation in a hard particle reinforced composite with a soft rubber-like matrix material using a numerical technique. The numerical specimen considered had a semi-circular notch with a linearly varying length. The initial crack size occurring at the notch tip was modeled and predicted using a micro/macro-approach along with a damage model. A criterion to predict the initial crack size was proposed based on the size of a localized unstable material zone. Different notch sizes were compared to their initial crack sizes.

Computational Evaluation of Effective Conductivity of Particulate Composites with Imperfect Interfaces

2009 ◽  
Vol 631-632 ◽  
pp. 35-40
Author(s):  
M. Zhang ◽  
Peng Cheng Zhai ◽  
Qing Jie Zhang
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Effective Properties ◽  
Effective Conductivity ◽  
Three Dimensional ◽  
Particulate Composite ◽  
Imperfect Interface ◽  
Particulate Composites ◽  
Imperfect Interfaces ◽  
Volume Fractions

This paper is aimed to numerically evaluate the effective thermal conductivity of randomly distributed spherical particle composite with imperfect interface between the constituents. A numerical homogenization technique based on the finite element method (FEM) with representative volume element (RVE) was used to evaluate the effective properties with periodic boundary conditions. Modified random sequential adsorption algorithm (RSA) is applied to generate the three dimensional RVE models of randomly distributed spheres of identical size with the volume fractions up to 50%. Several investigations have been conducted to estimate the influence of the imperfect interfaces on the effective conductivity of particulate composite. Numerical results reveal that for the given composite, due to the existence of an interfacial thermal barrier resistance, the effective thermal conductivity depends not only on the volume fractions of the particle but on the particle size.

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.

Effect of Hydrostatic Pressure on Damage in Particulate Composites

2001 ◽  
Author(s):  
Y. W. Kwon ◽  
C. T. Liu
Keyword(s):  
Hydrostatic Pressure ◽  
Volumetric Strain ◽  
Particulate Composite ◽  
Crack Size ◽  
Initial Crack ◽  
Material Behavior ◽  
Particulate Composites ◽  
Damage Growth ◽  
Damage Theory ◽  
Effect Of Hydrostatic Pressure

Abstract Hydrostatic pressure affects the damage growth in a particulate composite. As a result, an analytical model was presented to represent the damage growth in a particulate composite under various hydrostatic pressures. The model was based on a multi-level approach with damage description at the micro-level. A damage theory was presented to describe the material behavior under hydrostatic pressure. The effect of hydrostatic pressure was introduced to the damage theory through the damage function that was assumed to be a function of both deviatoric and volumetric strain energy densities. The predicted stress-strain curves with hydrostatic pressure compared well with the experimental data. Furthermore, the initial crack size at a notch tip was studied with and without hydrostatic pressure. The initial crack size determined from the computer modeling and simulation agreed well with the measured data with or without hydrostatic pressure.

A Three-Dimensional Unit Cell Model With Application Toward Particulate Composites

1995 ◽  
Vol 62 (1) ◽  
pp. 136-140 ◽  
Author(s):  
H. A. Wienecke ◽  
J. R. Brockenbrough ◽  
A. D. Romanko
Keyword(s):  
Cell Model ◽  
Three Dimensional ◽  
Unit Cube ◽  
Unit Cell ◽  
Particulate Composites ◽  
Unit Cell Model ◽  
Two Phase ◽  
Element Discretization ◽  
Cubic Symmetry ◽  
Dimensional Unit

A formulation of a fully three-dimensional unit cell model is presented for uniform general deformation at a point in a composite material. The unit cell model is constructed as a finite element discretization of the unit cube. General displacement periodicity boundary conditions are prescribed such that the cell may be considered as a representative volume element of material. As a particular application of the model, the problem of determining the least anisotropic periodic model of a particulate composite is considered, and comparisons are made with bounds for elastic two-phase composites possessing cubic symmetry.

scholarly journals A Lattice Model for Elastic Particulate Composites

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1584 ◽  
Author(s):  
Darius Zabulionis ◽  
Vytautas Rimša
Keyword(s):  
Mechanical Response ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Particulate Composite ◽  
High Volume ◽  
Spherical Particles ◽  
Particulate Composites ◽  
The Finite Element Method ◽  
Network Method

In the present article, a version of the lattice or spring network method is proposed to model the mechanical response of elastic particulate composites with a high volume fraction of spherical particles and with a much weaker matrix compared to the stiffness of the particles. The main subject of the article is the determination of the axial stiffnesses of the springs of the cell. A comparison of the mechanical response of a three-dimensional particulate composite cube obtained using the finite element method and the proposed methodology showed that the efficiency of the proposed methodology increases with an increasing volume fraction of the particles.

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