Micromechanical model for hydroxyapatite whisker reinforced polymer biocomposites

2006 ◽  
Vol 21 (8) ◽  
pp. 2136-2145 ◽  
Author(s):  
Weimin Yue ◽  
Ryan K. Roeder
Keyword(s):  
Aspect Ratio ◽  
High Density Polyethylene ◽  
Elastic Moduli ◽  
Volume Fraction ◽  
Micromechanical Model ◽  
Orientation Distribution ◽  
Ratio Distribution ◽  
Reinforced Polymer ◽  
Model Predictions ◽  
Aspect Ratio Distribution

A micromechanical model was developed to predict the elastic moduli of hydroxyapatite (HA) whisker reinforced polymer biocomposites based upon the elastic properties of each phase and the reinforcement volume fraction, morphology, and preferred orientation. The effects of the HA whisker volume fraction, morphology, and orientation distribution were investigated by comparing model predictions with experimentally measured elastic moduli for HA whisker reinforced high-density polyethylene composites. Predictions using experimental measurements of the HA whisker aspect ratio distribution and orientation distribution were also compared to common idealized assumptions. The best model predictions were obtained using the experimentally measured HA whisker aspect ratio distribution and orientation distribution.

Micromechanical Model for the Orthotropic Elastic Constants of Polyetheretherketone Composites Considering the Orientation Distribution of the Hydroxyapatite Whisker Reinforcements

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Justin M. Deuerling ◽  
J. Scott Vitter ◽  
Gabriel L. Converse ◽  
Ryan K. Roeder
Keyword(s):  
Elastic Constants ◽  
Volume Fraction ◽  
Flow Direction ◽  
Micromechanical Model ◽  
Orientation Distribution ◽  
Short Fiber ◽  
Preferred Orientation ◽  
Experimental Measurements ◽  
Fiber Reinforced ◽  
Model Predictions

Hydroxyapatite (HA) whisker reinforced polyetheretherketone (PEEK) composites have been investigated as bioactive materials for load-bearing orthopedic implants with tailored mechanical properties governed by the volume fraction, morphology, and preferred orientation of the HA whisker reinforcements. Therefore, the objective of this study was to establish key structure-property relationships and predictive capabilities for the design of HA whisker reinforced PEEK composites and, more generally, discontinuous short fiber-reinforced composite materials. HA whisker reinforced PEEK composites exhibited anisotropic elastic constants due to a preferred orientation of the HA whiskers induced during compression molding. Experimental measurements for both the preferred orientation of HA whiskers and composite elastic constants were greatest in the flow direction during molding (3-axis, C33), followed by the transverse (2-axis, C22) and pressing (1-axis, C11) directions. Moreover, experimental measurements for the elastic anisotropy and degree of preferred orientation in the same specimen plane were correlated. A micromechanical model accounted for the preferred orientation of HA whiskers using two-dimensional implementations of the measured orientation distribution function (ODF) and was able to more accurately predict the orthotropic elastic constants compared to common, idealized assumptions of randomly oriented or perfectly aligned reinforcements. Model predictions using the 3-2 plane ODF, and the average of the 3-1 and 3-2 plane ODFs, were in close agreement with the corresponding measured elastic constants, exhibiting less than 5% average absolute error. Model predictions for C11 using the 3-1 plane ODF were less accurate, with greater than 10% error. This study demonstrated the ability to accurately predict differences in orthotropic elastic constants due to changes in the reinforcement orientation distribution, which will aid in the design of HA whisker reinforced PEEK composites and, more generally, discontinuous short fiber-reinforced composites.

scholarly journals Mechanical Properties of a Biocomposite Based on Carbon Nanotube and Graphene Nanoplatelet Reinforced Polymers: Analytical and Numerical Study

2021 ◽  
Vol 5 (9) ◽  
pp. 234
Author(s):  
Marwane Rouway ◽  
Mourad Nachtane ◽  
Mostapha Tarfaoui ◽  
Nabil Chakhchaoui ◽  
Lhaj El Hachemi Omari ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Numerical Study ◽  
Turbine Blades ◽  
Natural Fibers ◽  
Computational Method ◽  
Wind Turbine Blades ◽  
Reinforced Polymer ◽  
Analytical Approaches

Biocomposites based on thermoplastic polymers and natural fibers have recently been used in wind turbine blades, to replace non-biodegradable materials. In addition, carbon nanofillers, including carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are being implemented to enhance the mechanical performance of composites. In this work, the Mori–Tanaka approach is used for homogenization of a polymer matrix reinforced by CNT and GNP nanofillers for the first homogenization, and then, for the second homogenization, the effective matrix was used with alfa and E-glass isotropic fibers. The objective is to study the influence of the volume fraction Vf and aspect ratio AR of nanofillers on the elastic properties of the composite. The inclusions are considered in a unidirectional and random orientation by using a computational method by Digimat-MF/FE and analytical approaches by Chamis, Hashin–Rosen and Halpin–Tsai. The results show that CNT- and GNP-reinforced nanocomposites have better performance than those without reinforcement. Additionally, by increasing the volume fraction and aspect ratio of nanofillers, Young’s modulus E increases and Poisson’s ratio ν decreases. In addition, the composites have enhanced mechanical characteristics in the longitudinal orientation for CNT- reinforced polymer and in the transversal orientation for GNP-reinforced polymer.

Viscoelastic behavior of epoxy resin reinforced with shape-memory-alloy wires

2020 ◽  
pp. 1045389X2097549
Author(s):  
Niloufar Bagheri ◽  
Mahmood M Shokrieh ◽  
Ali Saeedi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Epoxy Resin ◽  
Volume Fraction ◽  
Niti Alloy ◽  
Micromechanical Model ◽  
Viscoelastic Behavior ◽  
Mechanical Analysis ◽  
Reinforced Polymer ◽  
Small Volume Fraction

The effect of NiTi alloy long wires on the viscoelastic behavior of epoxy resin was investigated by utilizing the dynamic mechanical analysis (DMA) and a novel micromechanical model. The present model is capable of predicting the viscoelastic properties of the shape-memory-alloy (SMA) reinforced polymer as a function of the SMA volume fraction, initial martensite volume fraction, pre-strain level in wires, and the temperature variations. The model was verified by conducting experiments. Good agreement between the theoretical and experimental results was achieved. A parametric study was also performed to investigate the effect of SMA parameters. According to the results, by the addition of a small volume fraction of SMA, the storage modulus of the composite increases significantly, especially at higher temperatures. Moreover, applying a 4% pre-strain caused a 10% increase in the maximum value of the loss factor of the SMA reinforced epoxy in comparison with the 0% pre-strained SMA reinforced epoxy.

Interphase influences on the mechanical behavior of carbon nanotube–shape memory polymer nanocomposites: A micromechanical approach

2018 ◽  
Vol 30 (3) ◽  
pp. 463-478 ◽  
Author(s):  
MK Hassanzadeh-Aghdam ◽  
MJ Mahmoodi ◽  
R Ansari ◽  
A Darvizeh
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Shape Memory ◽  
Polymer Nanocomposites ◽  
Elastic Moduli ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Micromechanical Model ◽  
Elastic Behavior ◽  
Interphase Region

The effects of interphase characteristics on the elastic behavior of randomly dispersed carbon nanotube–reinforced shape memory polymer nanocomposites are investigated using a three-dimensional unit cell–based micromechanical method. The interphase region is formed due to non-bonded van der Waals interaction between a carbon nanotube and a shape memory polymer. The influences of temperature, diameter, volume fraction, and arrangement type of carbon nanotubes within the matrix as well as two interphase factors, including adhesion exponent and thickness on the carbon nanotube/shape memory polymer nanocomposite’s longitudinal and transverse elastic moduli, are explored extensively. Moreover, the results are presented for the shape memory polymer nanocomposites containing randomly oriented carbon nanotubes. The obtained results clearly demonstrate that the interphase region plays a crucial role in the modeling of the carbon nanotube/shape memory polymer nanocomposite’s elastic moduli. It is observed that the nanocomposite’s elastic moduli remarkably increase with increasing interphase thickness or decreasing adhesion exponent. It is found that when the interphase is considered in the micromechanical simulation, the shape memory polymer nanocomposite’s elastic moduli non-linearly increase as the carbon nanotube diameter decreases. The predictions of the present micromechanical model are compared with those of other analytical methods and available experiments.

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.

Aspect Ratio Analysis Using Image Processing for Rice Grain Quality

2010 ◽  
Vol 6 (5) ◽  
Author(s):  
Amit K Aggarwal ◽  
Ratan Mohan
Keyword(s):  
Image Processing ◽  
Aspect Ratio ◽  
Local Market ◽  
Rice Grain ◽  
Ratio Analysis ◽  
Ratio Distribution ◽  
Aspect Ratios ◽  
Percent Accuracy ◽  
Aspect Ratio Distribution

Determination of aspect ratio distribution is important for elongated, needle-shaped particles whose utility and/or value may depend on this feature. In this work rice grain is taken as an example of such a particle and its aspect ratio distribution in various samples is found using image processing. The samples examined were from three different grades (commonly termed as full, half and broken) sold in local market and priced according to their size. From the analysis, reference aspect ratios were assigned to classify the grains and hence determine the extent of off-size in each market grade. Further, the effectiveness of the technique to quantify mixed or adulterated grades was studied. It was found that it is possible to know the undesired content within 10 percent accuracy.

A Numerical Technique for Computing Effective Thermal Conductivity of Fluid-Particle Mixtures

2004 ◽  
Author(s):  
Satish Kumar ◽  
Jayathi Y. Murthy
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Aspect Ratio ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
Numerical Technique ◽  
Fluid Particle ◽  
Finite Volume Scheme ◽  
Ratio Distribution ◽  
Periodic Arrays

Periodic arrays of particles, foams, and other structures impregnated with a static fluid play an important role in heat transfer enhancement. In this paper, we develop a numerical method for computing conduction heat transfer in periodic beds by exploiting the periodicity of heat flux and the resulting linear variation of mean temperature. The numerical technique is developed within the framework of an unstructured finite volume scheme in order to enable the computation of effective thermal conductivity for complex fluid-particle arrangements. The method is applied to the computation of effective thermal conductivity of ordered as well as random beds of spheres and rods. The effect of varying surface area, aspect ratio, volume fraction, orientation, and distribution is studied for various solid-to-fluid conductivity ratios. Unlike classical theories which predict only a dependence on volume fraction, these direct simulations show that aspect ratio, distribution, and alignment of particles have an important influence on the effective thermal conductivity of the bed.

scholarly journals Creep of particle and short fibre reinforced polyurethane rubber

2021 ◽  
Author(s):  
Yi Cui ◽  
Trevor William Clyne
Keyword(s):  
Aspect Ratio ◽  
Volume Fraction ◽  
Creep Behaviour ◽  
Extrusion Process ◽  
Short Fibre ◽  
Stress Strain ◽  
Eshelby Model ◽  
Model Predictions ◽  
Short Fibres ◽  
Strain Testing

AbstractTensile stress–strain testing and creep testing have been carried out on a polyurethane rubber, at three temperatures, with and without either particulate or short fibre alumina reinforcement. A previous paper reported concerning composites with particulate reinforcement and the present work is focused on the effect of the fibres. The samples were made via a blending and extrusion process that produced a certain degree of fibre alignment (along the direction of loading). Prior milling procedures were used to produce fibres with two different ranges of aspect ratio (with averages about 10 and 16). When expressed as true stress–strain relationships, all materials exhibit approximately linear responses. The dependence of stiffness on the volume fraction and aspect ratio of the reinforcement was found to conform well to the Eshelby model predictions. Moreover, the creep behaviour of all of the materials can be captured well by a Miller–Norton formulation, using the average matrix stress predicted by the Eshelby model. A striking conclusion is that it is both predicted and observed that short fibres are much more effective in reducing the creep rate than is the case with particles.

scholarly journals A General Method for Estimating Bulk 2D Projections of Ice Particle Shape: Theory and Applications

2019 ◽  
Vol 76 (1) ◽  
pp. 305-332 ◽  
Author(s):  
Edwin L. Dunnavan ◽  
Zhiyuan Jiang
Keyword(s):  
Aspect Ratio ◽  
Particle Shape ◽  
Ratio Distribution ◽  
Aspect Ratios ◽  
Shape Uncertainty ◽  
Aspect Ratio Distribution ◽  
Spheroidal Geometry ◽  
Orientation Parameters ◽  
General Method

Abstract The orientation of falling ice particles directly influences estimates of microphysical and radiative bulk quantities as well as in situ retrievals of size, shape, and mass. However, retrieval efforts and bulk calculations often incorporate very basic orientations or ignore these effects altogether. To address this deficiency, this study develops a general method for projecting bulk distributions of particle shape for arbitrary orientations. The Amoroso distribution provides the most general bulk aspect ratio distribution for gamma-distributed particle axis lengths. The parameters that govern the behavior of this aspect ratio distribution depend on the assumed relationship between mass, maximum dimension, and aspect ratio. Individual spheroidal geometry allows for eccentricity quantities to linearly map onto ellipse analogs, whereas aspect ratio quantities map nonlinearly. For particles viewed from their side, this analytic distinction leads to substantially larger errors in projected aspect ratio than for projected eccentricity. Distribution transformations using these mapping equations and numerical integration of projection kernels show that both truncation of size distributions and changes in Gaussian dispersion can alter the modality and shape of projection distributions. As a result, the projection process can more than triple the relative entropy between the spheroidal and projection distributions for commonly assumed model and orientation parameters. This shape uncertainty is maximized for distributions of highly eccentric particles and for particles like aggregates that are thought to fall with large canting-angle deviations. As a result, the methods used to report projected aspect ratios and the corresponding values should be questioned.

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