Effective Thermoelastic Moduli of a Unidirectional Fiber Composite Containing Interfacial Arc Microcracks

1996 ◽  
Vol 63 (1) ◽  
pp. 210-217 ◽  
Author(s):  
G. P. Tandon ◽  
N. J. Pagano
Keyword(s):  
Volume Fraction ◽  
Fiber Composite ◽  
Unidirectional Composite ◽  
Variational Model ◽  
Concentric Cylinder ◽  
Fiber Volume ◽  
Cylinder Model ◽  
Unidirectional Fiber Composite ◽  
Thermoelastic Response

In this work, we have employed a variational model to examine the effect of fiber-matrix debonding on the thermoelastic response of a unidirectional composite. The model is designed to represent the concentric cylinder model of a composite representative volume element and it contains the capability to enhance the accuracy of a given numerical solution. The effect of the extent of debonding as well as fiber volume fraction on all the effective moduli of the unidirectional composite has been examined. Numerical results reported in the literature are compared with the results of the model developed in the present study to examine the quality of the model.

Semianalytical compressive strength criteria for unidirectional composites

2017 ◽  
Vol 37 (4) ◽  
pp. 238-246
Author(s):  
Uri Breiman ◽  
Jacob Aboudi ◽  
Rami Haj-Ali
Keyword(s):  
Experimental Data ◽  
Compressive Strength ◽  
Volume Fraction ◽  
Unidirectional Composite ◽  
Fiber Volume ◽  
Unidirectional Composites ◽  
Analysis And Design ◽  
Composite Systems ◽  
Wide Range ◽  
Laminated Structures

The compressive strength of unidirectional composites is strongly influenced by the elastic and strength properties of the fiber and matrix phases, as well as by the local geometrical properties, such as fiber volume fraction, misalignment, and waviness. In the present investigation, two microbuckling criteria are proposed and examined against a large volume of measured data of unidirectional composites taken from the literature. The first criterion is based on the compressive strength formulation using the buckling of Timoshenko’s beam. It contains a single parameter that can be determined according to the best fit to experimental data for various types of polymeric matrix composites. The second criterion is based on buckling-wave propagation analogy using the solution of an eigenvalue problem. Both criteria provide closed-form expressions for the compressive strength of unidirectional composites. We propose modifications of the two criteria by a fitting approach, for a wide range of fiber volume fractions, applied to four classes of unidirectional composite systems. Furthermore, a normalized form of the two models is presented after calibration in order to compare their prediction against experimental data for each of the material systems. The new modified criteria are shown to give a good match to a wide range of unidirectional composite systems. They can be employed as practical compression failure criteria in the analysis and design of laminated structures.

Development of Generalized Plane-Strain Tensors for the Concentric Cylinder

1995 ◽  
Vol 62 (3) ◽  
pp. 590-594
Author(s):  
N. Chandra ◽  
Zhiyum Xie
Keyword(s):  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Transformation Strain ◽  
Inclusion Problem ◽  
Infinite Domain ◽  
Concentric Cylinder ◽  
Finite Radius ◽  
Fiber Volume ◽  
Thermal Residual Stresses ◽  
The Matrix

A pair of two new tensors called GPS tensors S and D is proposed for the concentric cylindrical inclusion problem. GPS tensor S relates the strain in the inclusion constrained by the matrix of finite radius to the uniform transformation strain (eigenstrain), whereas tensor D relates the strain in the matrix to the same eigenstrain. When the cylindrical matrix is of infinite radius, tensor S reduces to the appropriate Eshelby’s tensor. Explicit expressions to evaluate thermal residual stresses σr, σθ and σz in the matrix and the fiber using tensor D and tensor S, respectively, are developed. Since the geometry of the present problem is of finite radius, the effect of fiber volume fraction on the stress distribution can be easily studied. Results for the thermal residual stress distributions are compared with Eshelby’s infinite domain solution and finite element results for a specified fiber volume fraction.

Determination of the Directional Dependent In-Plane Thermal Conductivity of K63B12 Pitch-Fiber/Epoxy Composite

2004 ◽  
Author(s):  
Jessica N. McClay ◽  
Peter Joyce ◽  
Andrew N. Smith
Keyword(s):  
Thermal Conductivity ◽  
Thermal Management ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Epoxy Composite ◽  
Fiber Composite ◽  
Fiber Volume ◽  
State Technique ◽  
Fiber Composite Materials

Measurements of the in-plane thermal conductivity and the directional dependence of Mitsubishi K63B12 pitch-fiber/Epoxy composite from Newport Composites are reported. This composite is being explored for use in the Avanced Seal Delivery System for effective thermal management. The thermal conductivity was measured using a steady state technique. The experimental results were then compared to a model of the thermal conductivity based on the direction of the fibers. These estimates are based on the properties of the constituent materials and volume of fibers in the sample. Therefore the density and the fiber volume fraction were experimentally measured. The thermal conductivity is clearly greatest in the direction of the fibers and decreases as the fibers are rotated off axis. In the case of pitch fiber composite materials, the contribution of the fibers to the thermal conductivity dominates. The experimental data clearly followed the correct trends; however, the measured values were 25% to 35% lower than predicted.

Fracture behavior of short-fiber reinforced materials

1992 ◽  
Vol 7 (11) ◽  
pp. 3120-3131 ◽  
Author(s):  
Michael Murat ◽  
Micha Anholt ◽  
H. Daniel Wagner
Keyword(s):  
Fracture Process ◽  
Fracture Behavior ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Finite Size ◽  
Critical Length ◽  
Short Fiber ◽  
Fiber Volume ◽  
Linear Elastic ◽  
Fiber Reinforced Materials

A discrete model of springs with bond-bending forces is proposed to simulate the fracture process in a composite of short stiff fibers in a softer matrix. Both components are assumed to be linear elastic up to failure. We find that the critical fiber length of a single fiber composite increases roughly linearly with the ratio of the fiber elastic modulus to matrix modulus. The finite size of the lattice in the direction perpendicular to the fiber orientation considerably alters the behavior of the critical length for large values of the modulus ratio. The simulations of the fracture process reveal different fracture behavior as a function of the fiber content and length. We calculate the Young's modulus, fracture stress, and the strain at maximum stress as a function of the fiber volume fraction and aspect ratio. The results are compared with the predictions of other theoretical studies and experiments.

On the Actuation Authority of Adaptive Sandwich Beam with Composite Actuators: Coupled Finite Element Analysis

2012 ◽  
Vol 585 ◽  
pp. 332-336 ◽  
Author(s):  
K. Venkata Rao ◽  
S. Raja ◽  
T. Munikenche Gowda
Keyword(s):  
Numerical Experiments ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Sandwich Beam ◽  
Beam Theory ◽  
Beam Element ◽  
Fiber Volume ◽  
Element Analysis ◽  
Active Fiber ◽  
Macro Fiber Composite

A two noded active sandwich beam element is formulated by employing layerwise Timoshenko’s beam theory. Displacement continuity conditions are imposed between different layers of the sandwich. This element is used to model an adaptive sandwich beam with macro-fiber composite (MFC) as extension actuator and shear actuated fiber composite (SAFC) as shear actuator. Influence of thickness and volume fraction of the active fiber (PZT-5A and single crystal PMN-PT) in the composite actuators on the actuation performance of the sandwich beam is investigated. Based on several numerical experiments, it is found that the PMN-PT based shear actuators give maximum actuation authority for the volume fraction of the fibers in the range of 80%-85%, whereas in case of PZT-5A based shear actuators the actuation authority remains maximum for the fiber volume fractions 80% and above.

Application of Carbon Fiber-Based Composite for Electric Vehicle

2014 ◽  
Vol 896 ◽  
pp. 574-577 ◽  
Author(s):  
Miftahul Anwar ◽  
Indro Cahyono Sukmaji ◽  
Wisnu R. Wijang ◽  
Kuncoro Diharjo
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Glass Fiber ◽  
External Load ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Impact Testing ◽  
Fiber Volume ◽  
Glass Fiber Composite ◽  
Hybrid Carbon

In the present work, we study how to improve mechanical properties of carbon fiber reinforced plastics (CFRP) in order to increase crashworthiness probability. Experimentally, hybrid carbon /glass fiber composite was made in order to get higher mechanical properties. As a results, with increasing carbon fiber volume fraction (% vol.), tensile strength and flexural strength of the composite are increased. Simulation of impact testing is also performed using data properties taken from the experiment with variation of impact forces on front bumper structure. By varying external load to the bumper, the result shows that higher thickness of hybrid carbon/glass fiber composite has always smaller stress values than thinner one. On the other hand, the displacement of hybrid carbon/glass car bumper increases linearly with increasing external load.

scholarly journals TENSILE TEST ANALYSIS OF NATURAL FIBER REINFORCED COMPOSITE

2014 ◽  
pp. 148-152
Author(s):  
G. VELMURUGAN ◽  
D. VADIVEL ◽  
R. ARRAVIND ◽  
A. MATHIAZHAGAN ◽  
S.P. VENGATESAN
Keyword(s):  
Natural Fiber ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Tensile Load ◽  
Experimental Result ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Test Analysis ◽  
Reinforced Composite ◽  
Strain Stress

This project mainly deals with analysis of tensile properties of Palmyra fiber Reinforced Epoxy Composite that is suitable for automobile application. First, the property of material was obtained on the basis of some assumptions (i.e., Rule of Mixture) and was modeled with reference to ASTM D638. Here the simulation was carried out on specimen under different fiber volume fraction and fiber length. The present work includes the Analysis of Palmyra Fiber Reinforced Epoxy Composites using FEA with various fiber volume fractions and these results were validated with the experimental result. The tensile property of Palmyra fiber composite material can be obtained by using tensometer.During the tensile load, the maximum strain, stress and displacement were obtained and, then this experimental result was compared with the analytical results and the error percentage of these results were calculated.

Effects of vacuum pressure, inlet pressure, and mold temperature on the void content, volume fraction of polyester/e-glass fiber composites manufactured with VARTM process

2011 ◽  
Vol 45 (26) ◽  
pp. 2727-2742 ◽  
Author(s):  
Vishwanath R. Kedari ◽  
Basil I. Farah ◽  
Kuang-Ting Hsiao
Keyword(s):  
Glass Fiber ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Mold Temperature ◽  
Vacuum Pressure ◽  
Inlet Pressure ◽  
Void Content ◽  
Fiber Volume ◽  
Vartm Process

Vacuum-assisted resin transfer molding (VARTM) process is one of the liquid composite molding (LCM) processes aimed at producing high-quality composite parts. The void content and fiber volume fraction of a VARTM part can be affected by many parameters and is critical to the mechanical properties and the quality of the part. In this paper, a series of experiments were conducted with a heated dual pressure control VARTM setup for investigating the effects of vacuum pressure, inlet pressure, and mold temperature on the void content and fiber volume fraction of polyester/E-glass fiber composite. It was found that stronger vacuum and higher mold temperature can better control and increase the fiber volume fraction; however, such a combination of strong vacuum and high mold temperature may also require a reduced inlet pressure for minimizing the void content. The need of pressure reduction can be explained with the compatibility between Darcy's flow and capillary flow in the fiber preform and can be calculated based on the room temperature VARTM results. The experimental results suggest that high mold temperature, high vacuum, and appropriately reduced inlet pressure can produce a VARTM part with high fiber volume fraction and low void content.

Micromechanics of a Smart Composite Actuator Embedded With Hollow Piezoelectric Fibers

2011 ◽  
Author(s):  
Sontipee Aimmanee ◽  
Supharoek Trakarnkulchai ◽  
Pakinee Aimmanee
Keyword(s):  
Volume Fraction ◽  
Transversely Isotropic ◽  
Material System ◽  
Smart Composite ◽  
Concentric Cylinder ◽  
Fiber Volume ◽  
Reinforced Composite ◽  
Concentric Cylinders ◽  
Matrix Volume ◽  
Composite Actuator

This paper presents a development of mathematical models for predicting the effective elastic and piezoelectric properties of a Smart Composite Actuator (SCA) reinforced with transversely isotropic piezoelectric hollow fibers. The models are established based on micromechanics of representative volume element of concentric cylinders or so-called concentric cylinder model (CCM). Five elastic constants and two piezoelectric coefficients are predicted as a function of fiber volume fraction, matrix volume fraction, and their constituents’ properties in the SCA. Numerical results of a chosen material system are obtained and discussed. The models can be found useful for developing a SCA or a novel hollow fiber-reinforced composite with the desired properties.

Electrical Resistance Properties of Cement/Carbon Fiber Composite

2012 ◽  
Vol 560-561 ◽  
pp. 830-836 ◽  
Author(s):  
Bi Qin Dong ◽  
Feng Xing ◽  
Hong Zhi Cui ◽  
Zong Jin Li
Keyword(s):  
Carbon Fiber ◽  
Electrical Resistance ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Cement Composite ◽  
Carbon Fiber Composite ◽  
Fiber Volume ◽  
Study Results ◽  
Short Carbon

In this article, study results of the electrical resistance properties of cement/carbon fiber composite are presented. Using a normal mixing and compacting method, up to 0.85v.% short carbon fiber can be easily incorporated into the cement composite. And its electrical resistivity properties are measured. The resistivity of specimens decreases greatly with the volume fraction of fibers increasing. Moreover, it is found that there is a saturation point for fiber volume fraction. Beyond that, the change of resistivity with the variation of fiber volume fraction becomes much flat. Another interest finding is that the resistivity of the cement materials is a function of frequency of applied voltage. The microstructure associated with the electrical properties of composite is observed. It is possible to apply cement/carbon fiber composite as an electromagnetic shielding composite and so on.

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