Effective Thermal Conductivity of Ordered Short-Fiber Composites With Single-Fiber Uniform Hexagonal Prism Cell

2012 ◽  
Author(s):  
Marcelo B. Martinez ◽  
Manuel E. Cruz ◽  
Carlos F. Matt
Keyword(s):  
Finite Element ◽  
Effective Properties ◽  
Effective Conductivity ◽  
Numerical Study ◽  
Fiber Composite ◽  
Fiber Composites ◽  
Short Fiber ◽  
Single Fiber ◽  
Hexagonal Prism ◽  
Element Discretization

The bulk behavior of short-fiber composite materials in mechanical, thermal, and electrical applications is of great engineering interest. The reliability of analytical and numerical studies dedicated to these topics depends to a large extent on the postulated, or prescribed, microstructure configurations. Of course, different spatial distributions of fibers lead to different configurations, which in turn influence the effective properties. There are no established (or benchmarked) microstructure configurations (or models) to be used in investigations aimed at calculating the macroscopic behavior of classes of real composite material bodies. In the present numerical study of heat conduction in composites, accurate results for the longitudinal and transverse effective thermal conductivities of short-fiber composites with single-fiber uniform hexagonal prism cell are calculated and validated. The three-dimensional periodic cell microstructure consists of one short circular cylindrical fiber placed at the center, and perpendicular to the two parallel regular hexagons, of the prism. Previous continuous formulation and computational implementation are employed, based on the method of homogenization and finite element discretization. A procedure for generating the domain of the uniform hexagonal prism cell, and the respective tetrahedral finite-element mesh, has been realized using a third-party software. The numerical effective conductivity results obtained in the 3-D calculations are validated against analytical results for the 2-D hexagonal array of circular cylinders.

scholarly journals Study on the flexure performance of fine concrete sheets reinforced with textile and short fiber composites

2019 ◽  
Vol 275 ◽  
pp. 02006
Author(s):  
Qiao-chu Yang ◽  
Qin Zhang ◽  
Su-su Gong ◽  
San-ya Li
Keyword(s):  
Glass Fiber ◽  
Fiber Composite ◽  
Basalt Fiber ◽  
Fiber Composites ◽  
Short Fiber ◽  
Calcium Carbonate Whisker ◽  
Flexural Tests ◽  
Short Fiber Composite ◽  
Fiber Mesh ◽  
Concrete Matrix

In order to study the influences of the contents of short fiber on the mechanical properties of concrete matrix, the properties of compressive, flexure and splitting of concrete matrix reinforced by alkali resistant glass fiber and calcium carbonate whisker were tested. To study the reinforced effect of different scale fibers on the flexure behavior of fine concrete sheets, the flexural tests of concrete sheet of fine concrete reinforced with basalt fiber mesh and short fiber composites were carried out. The results show that the properties of the compressive, flexure and splitting of fine concrete reinforced with appropriate amount of alkali resistant glass fiber and carbonate whisker are improved compared with that of concrete reinforced by one type of fiber. The flexure properties of the concrete sheets are improved obviously when continuous fiber textile and short fiber composite are adopted to reinforce.

A Mechanistic Approach to Matrix Cracking Coupled with Fiber–Matrix Debonding in Short-Fiber Composites

2005 ◽  
Vol 127 (3) ◽  
pp. 337-350 ◽  
Author(s):  
Ba Nghiep Nguyen ◽  
Brian J. Tucker ◽  
Mohammad A. Khaleel
Keyword(s):  
Damage Mechanics ◽  
Fiber Composite ◽  
Fiber Composites ◽  
Short Fiber ◽  
Matrix Cracking ◽  
Element Analysis ◽  
Pull Out ◽  
Stiffness Reduction ◽  
Mechanistic Approach ◽  
Fiber Matrix

A micro–macro mechanistic approach to damage in short-fiber composites is developed in this paper. At the microscale, a reference aligned fiber composite is considered for the analysis of the damage mechanisms such as matrix cracking and fiber–matrix debonding using the modified Mori–Tanaka model. The associated damage variables are defined, and the stiffness reduction law dependent on these variables is established. The stiffness of a random fiber composite containing random matrix microcracks and imperfect interfaces is then obtained from that of the reference composite, which is averaged over all possible orientations and weighted by an orientation distribution function. The macroscopic response is determined using a continuum damage mechanics approach and finite element analysis. Final failure resulting from saturation of matrix microcracks, fiber pull-out and breakage is modeled by a vanishing element technique. The model is validated using the experimental results found in literature as well as the results obtained for a random chopped fiber glass–vinyl ester system. Acoustic emission techniques were used to quantify the amount and type of damage during quasi-static testing.

scholarly journals Estimation of the physical properties of nanocomposites by finite-element discretization and Monte Carlo simulation

2013 ◽  
Vol 371 (1993) ◽  
pp. 20120494 ◽  
Author(s):  
P. Spanos ◽  
P. Elsbernd ◽  
B. Ward ◽  
T. Koenck
Keyword(s):  
Finite Element ◽  
Monte Carlo ◽  
Electrical Properties ◽  
Volume Fraction ◽  
Effective Conductivity ◽  
Numerical Models ◽  
Strain Curve ◽  
Identification Algorithm ◽  
Element Discretization

This paper reviews and enhances numerical models for determining thermal, elastic and electrical properties of carbon nanotube-reinforced polymer composites. For the determination of the effective stress–strain curve and thermal conductivity of the composite material, finite-element analysis (FEA), in conjunction with the embedded fibre method (EFM), is used. Variable nanotube geometry, alignment and waviness are taken into account. First, a random morphology of a user-defined volume fraction of nanotubes is generated, and their properties are incorporated into the polymer matrix using the EFM. Next, incremental and iterative FEA approaches are used for the determination of the nonlinear properties of the nanocomposite. For the determination of the electrical properties, a spanning network identification algorithm is used. First, a realistic nanotube morphology is generated from input parameters defined by the user. The spanning network algorithm then determines the connectivity between nanotubes in a representative volume element. Then, interconnected nanotube networks are converted to equivalent resistor circuits. Finally, Kirchhoff's current law is used in conjunction with FEA to solve for the voltages and currents in the system and thus calculate the effective electrical conductivity of the nanocomposite. The model accounts for electrical transport mechanisms such as electron hopping and simultaneously calculates percolation probability, identifies the backbone and determines the effective conductivity. Monte Carlo analysis of 500 random microstructures is performed to capture the stochastic nature of the fibre generation and to derive statistically reliable results. The models are validated by comparison with various experimental datasets reported in the recent literature.

Bounds on the Transverse Effective Conductivity of Computer-Generated Fiber Composites

1982 ◽  
Vol 49 (2) ◽  
pp. 319-326 ◽  
Author(s):  
J. J. McCoy
Keyword(s):  
Thermal Conductivity ◽  
Effective Conductivity ◽  
Fiber Composite ◽  
Effective Property ◽  
Fiber Composites ◽  
Area Fraction ◽  
Fiber Area ◽  
Single Body ◽  
Transverse Thermal Conductivity ◽  
Dilute Suspension

Using trial functions that are motivated by single-body calculations, we have derived bounds on the effective transverse thermal conductivity of a fiber composite. These bounds incorporate both fiber area fraction information and some information of the configurational statistics. Simplified expressions for the bounds are obtained for the limits of widely differing conductivity values for the constitutent phases, and of a dilute suspension. The bounds are made specific for a given computer-generated fiber composite and these specific bounds are compared with the best available bounds that require area fraction information alone. The conclusions reached are that configuration statistics are significant for effective property calculations for moderately dense composites for component conductivity values that differ by some one to two orders of magnitude, or greater. Further, the bounds based on the single-body calculation are reasonably close for component conductivity values that differ by some two orders of magnitude, or less.

scholarly journals Numerical study on rupture process of fiber-reinforced composites

2018 ◽  
Vol 16 (1_suppl) ◽  
pp. 46-54
Author(s):  
Daguo Wang ◽  
Chaochao Han ◽  
Bing Xu ◽  
Bin Li
Keyword(s):  
Tensile Strength ◽  
Numerical Study ◽  
Element Model ◽  
Fiber Composites ◽  
Composite Fiber ◽  
Single Fiber ◽  
Tensile Failure ◽  
Uniaxial Tensile ◽  
Total Width ◽  
Uniaxial Tensile Stress

Introduction: This study aims to investigate the strength characteristics of fiber composites under uniaxial tensile stress. Methods: A tensile failure finite element model based on fracture mechanics was built for fiber composites. The principal stress concentration–release–transfer evolution and the crack propagation of the composites under the conditions of equal single fiber width, unequal quantity, and equal total fiber width and unequal quantity were discussed. Results: The tensile strength of the composites increased with fiber quantity when the width of each single fiber was equal. Conclusions: The tensile strength of the composites increased with fiber quantity when the total width of the composite fiber was equal.

Development of a PZT Fiber/Piezo-Polymer Composite Actuator With Interdigitated Electrodes

2001 ◽  
Author(s):  
Cheol Kim ◽  
Kun-Hyung Koo
Keyword(s):  
Composite Plate ◽  
Effective Properties ◽  
Fiber Composite ◽  
Matrix Material ◽  
Three Dimensional ◽  
Fiber Composites ◽  
Numerical Analyses ◽  
Interdigitated Electrodes ◽  
Composite Actuator ◽  
Piezoelectric Fiber

Abstract Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material. This paper presents a modified micro-electromechanical model and numerical analyses of piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Various concepts from different backgrounds including three-dimensional linear elastic and dielectric theories have been incorporated into the present linear piezoelectric model. The rule of mixture and the modified method to calculate effective properties of fiber composites were extended to apply to the PFPMIDE model. The new model was validated comparing with available experimental data and other analytical results. To see the structural responses of a composite plate integrated with the PFPMIDE, three-dimensional finite element formulations were derived. Numerical analyses show that the shape of the graphite/epoxy composite plate with the PFPMIDE may be controlled by judicious choice of voltages, piezoelectric fiber angles, and elastic tailoring of the composite plate.

Sign in / Sign up

Export Citation Format

Share Document