Limitations on the Use of Effective Properties for Multicomponent Materials

2008 ◽  
Vol 24 (1) ◽  
pp. 95-102
Author(s):  
R. Han ◽  
M. S. Ingber ◽  
S. C. Hsiao
Keyword(s):  
Composite Materials ◽  
Effective Properties ◽  
Poisson Ratio ◽  
Matrix Material ◽  
Effective Property ◽  
Shear Loading ◽  
Functionally Graded ◽  
Dispersed Phase ◽  
Shear Moduli ◽  
Young’S Moduli

ABSTRACTMulticomponent composite materials comprised of a dispersed phase suspended in a matrix material are important in a wide variety of scientific and engineering applications including electronic encapsulation, functionally graded materials, and fiber-reinforced structural components among others. Modelling of this class of composites is typically performed using an effective property approach. This approach presumes that the characteristic dimension of the dispersed phase elements is small in comparison to the characteristic length scale of the physical problem under consideration. However, it is not possible to predict a third effective elastic property based on two independent effective elastic properties as it is for homogeneous elastic isotropic materials. Therefore, a macroscale simulation based on an effective Young's modulus and Poisson ratio may yield poor results for a material subjected to shear loading since there is a potentially incorrect presumed effective shear modulus for the simulation. In the current research, boundary element simulations are performed for mesoscopic samples of composite materials to determine effective bulk moduli, shear moduli, Young's moduli, and Poisson ratios. From these analyses, limitations in the effective property approach can be examined.

Study on Mechanical Properties of Wood Plastic Composites

2012 ◽  
Vol 182-183 ◽  
pp. 307-310
Author(s):  
Fang Huang
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Composite Materials ◽  
Matrix Material ◽  
Material Strength ◽  
Dispersed Phase ◽  
Wood Plastic Composites ◽  
Reinforced Composite ◽  
Plastic Composites ◽  
Pure Matrix

Composite material has many excellent properties, current, receives special attention was paid to its mechanical properties. By adding the dispersed phase can make the strength of the composites than did not join the dispersed phase of pure matrix material strength several times or several times. Composite materials are often called fiber ( or other dispersed phase) reinforced composite materials.

scholarly journals Design of Kinematic Connectors for Microstructured Materials Produced by Additive Manufacturing

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1500
Author(s):  
Miguel R. Silva ◽  
João A. Dias-de-Oliveira ◽  
António M. Pereira ◽  
Nuno M. Alves ◽  
Álvaro M. Sampaio ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Functionally Graded Materials ◽  
Cellular Structure ◽  
Young's Modulus ◽  
Functionally Graded ◽  
Graded Materials ◽  
Mean Values ◽  
Shear Moduli ◽  
Young’S Moduli ◽  
Unit Cells

The main characteristic of materials with a functional gradient is the progressive composition or the structure variation across its geometry. This results in the properties variation in one or more specific directions, according to the functional application requirements. Cellular structure flexibility in tailoring properties is employed frequently to design functionally-graded materials. Topology optimisation methods are powerful tools to functionally graded materials design with cellular structure geometry, although continuity between adjacent unit-cells in gradient directions remains a restriction. It is mandatory to attain a manufacturable part to guarantee the connectedness between adjoining microstructures, namely by ensuring that the solid regions on the microstructure’s borders i.e., kinematic connectors) match the neighboring cells that share the same boundary. This study assesses the kinematic connectors generated by imposing local density restrictions in the initial design domain (i.e., nucleation) between topologically optimised representative unit-cells. Several kinematic connector examples are presented for two representatives unit-cells topology optimised for maximum bulk and shear moduli with different volume fractions restrictions and graduated Young’s modulus. Experimental mechanical tests (compression) were performed, and comparison studies were carried out between experimental and numerical Young’s modulus. The results for the single maximum bulk for the mean values for experimental compressive Young’s modulus (Ex¯) with 60%Vf show a deviation of 9.15%. The single maximum shear for the experimental compressive Young’s modulus mean values (Ex¯) with 60%Vf, exhibit a deviation of 11.73%. For graded structures, the experimental mean values of compressive Young’s moduli (Ex¯), compared with predicted total Young’s moduli (ESe), show a deviation of 6.96 for the bulk graded structure. The main results show that the single type representative unit-cell experimental Young’s modulus with higher volume fraction presents a minor deviation compared with homogenized data. Both (i.e., bulk and shear moduli) graded microstructures show continuity between adjacent cells. The proposed method proved to be suitable for generating kinematic connections for the design of shear and bulk graduated microstructured materials.

scholarly journals Analytical solutions for the effective viscoelastic properties of composite materials with different shapes of inclusions

2021 ◽  
pp. 4-4
Author(s):  
Minh-Quan Thai ◽  
Sy-Tuan Nguyen ◽  
Thanh-Sang Nguyen ◽  
Phu-Son Mai
Keyword(s):  
Composite Materials ◽  
Viscoelastic Properties ◽  
Effective Properties ◽  
Poisson Ratio ◽  
Viscoelastic Behavior ◽  
Theory Of Elasticity ◽  
Homogenization Theory ◽  
Isotropic Case ◽  
Time Space ◽  
Different Shapes

This paper aims to model the effect of different shapes of inclusions on the homogenized viscoelastic properties of composite materials made of a viscoelastic matrix and inclusion particles. The viscoelastic behavior of the matrix phase is modeled by the Generalized Maxwell rheology. The effective properties are firstly derived by combining the homogenization theory of elasticity and the correspondence principle. Then, the effective rheological properties in time space are explicitly derived without using the complex inverse Laplace-Carson transformation (LC). Closed-form solutions for the effective bulk and shear rheological viscoelastic properties, the relaxation and creep moduli as well as the Poisson ratio are obtained for the isotropic case with random orientation distribution and different shapes of inclusions: spherical, oblate and elongate inclusions. The developed approach is validated against the exact solutions obtained by the classical inverse LC method. It is observed that the homogenized viscoelastic moduli are highly sensitive to different shapes of inclusions.

scholarly journals A micropolar model for elastic properties in functionally graded materials

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401878952 ◽  
Author(s):  
Shengyao Fan ◽  
Zhanqi Cheng
Keyword(s):  
Particle Size ◽  
Elastic Properties ◽  
Functionally Graded Materials ◽  
Effective Properties ◽  
Matrix Material ◽  
Functionally Graded ◽  
Two Phase ◽  
Graded Materials ◽  
Micromechanics Model ◽  
Matrix Zone

By considering the description of phase volume fractions, a micromechanics model is presented for predicting the elastic mechanical properties of isotropic two-phase functionally graded materials. The particle size dependence of the overall elasticity of functionally graded materials is not generally considered by classical continuum micromechanics; however, being based on micropolar theory, the presented micromechanics model is able to study such size effects. As the effective material properties vary gradually along the gradation direction, a functionally graded material can be divided into two distinct zones: the particle–matrix zone and the transition zone. In the particle–matrix zone, the matrix material is idealized as a micropolar continuum and Mori–Tanaka’s method is extended to the micropolar medium to evaluate the effective elastic properties. The effective properties across the gradation forms are further derived and the effects of particle size on the effective properties of a functionally graded materials are also studied. The validity and effectiveness of the present model is demonstrated by comparing the model results with other model outputs and experimental data.

New results in the theory of elasticity for two-dimensional composites

1992 ◽  
Vol 438 (1904) ◽  
pp. 531-544 ◽  
Keyword(s):  
Composite Materials ◽  
Elastic Constants ◽  
Matrix Material ◽  
Plane Elasticity ◽  
Theory Of Elasticity ◽  
Two Dimensional ◽  
Shear Moduli ◽  
The Matrix ◽  
Multicomponent Composite ◽  
Proven Theorem

We bring together and discuss a number of exact relationships in two-dimensional (or plane) elasticity, that are useful in studying the effective elastic constants and stress fields in two-dimensional composite materials. The first of these dates back to Michell (1899) and states that the stresses, induced by applied tractions, are independent of the elastic constants in a two-dimensional material containing holes. The second involves the use of Dundurs constants which, for a composite consisting of two isotropic elastic phases, reduce the dependence of stresses on the elastic constants from three independent dimensionless parameters to two. It is shown that these two results are closely related to a recently proven theorem by Cherkaev, Lurie and Milton, which we use to show that the effective Young’s modulus of a sheet containing holes is independent of the Poisson’s ratio of the matrix material. We also show that the elastic moduli of a composite can be found exactly if the shear moduli of the components are all equal; a previously known result. We illustrate these results with computer simulations, where appropriate. Finally we conjecture on generalizations to multicomponent composite materials and to situations where the bonding between the phases is not perfect.

The Effective Properties of Composite Materials With Constant Reinforcement Density by the Linear Mori-Tanaka Method

1994 ◽  
Vol 116 (3) ◽  
pp. 428-437 ◽  
Author(s):  
J. R. Zuiker ◽  
G. J. Dvorak
Keyword(s):  
Composite Materials ◽  
Volume Fraction ◽  
Effective Properties ◽  
Functionally Graded ◽  
Local Fields ◽  
Original Form ◽  
Constant Field ◽  
Inhomogeneous Materials ◽  
Reinforcement Density ◽  
Variable Reinforcement

In its original form, the Mori-Tanaka method estimates constant overall properties of statistically homogeneous composite materials subjected to uniform overall stresses, strain or temperature changes, from averages of local fields in the phases. To permit applications involving large overall stress and/or temperature gradients, and functionally graded materials with a variable reinforcement density, the method has been extended to linearly variable overall and local fields by Zuiker and Dvorak (Composites Engineering, Vol. 4, 19–35, 1994) as a first step toward application of the method to statistically inhomogeneous materials with variable reinforcement density. Here, the effective properties are examined in detail. Non-zero components of the stiffness matrix are shown to satisfy invariance requirements and to vary with reinforcement volume fraction and size of the representative volume. It is shown that the linear and constant field approaches provide different estimates of overall properties for small representative volumes, but nearly identical estimates for large volumes.

Mathematical Model of the Effective Properties of a Fiber Reinforced Composite with a Linearly Graded Transition Zone

2010 ◽  
Vol 38 (4) ◽  
pp. 286-307
Author(s):  
Carey F. Childers
Keyword(s):  
Mathematical Model ◽  
Transition Zone ◽  
Effective Properties ◽  
Local Stress ◽  
Stress And Strain ◽  
Fiber Reinforced ◽  
Strain Fields ◽  
Shear Moduli ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite

Abstract Tires are fabricated using single ply fiber reinforced composite materials, which consist of a set of aligned stiff fibers of steel material embedded in a softer matrix of rubber material. The main goal is to develop a mathematical model to determine the local stress and strain fields for this isotropic fiber and matrix separated by a linearly graded transition zone. This model will then yield expressions for the internal stress and strain fields surrounding a single fiber. The fields will be obtained when radial, axial, and shear loads are applied. The composite is then homogenized to determine its effective mechanical properties—elastic moduli, Poisson ratios, and shear moduli. The model allows for analysis of how composites interact in order to design composites which gain full advantage of their properties.

Thermal Property Evaluation of Chilled Aluminum-Alumina MMC

2015 ◽  
Vol 1101 ◽  
pp. 79-82
Author(s):  
B.C. Suresh ◽  
S.B. Arun
Keyword(s):  
Thermal Expansion ◽  
Composite Materials ◽  
Thermal Property ◽  
Coefficient Of Thermal Expansion ◽  
Matrix Material ◽  
High Strength ◽  
Stir Casting ◽  
Al Alloy ◽  
Industrial Growth ◽  
Property Evaluation

Now a day’s composite materials are taking very important role in industrial growth. Composite materials are widely used in Automobiles, aerospace, submarine and also in other major fields, due to their special characteristics like light weight, high strength, stiffness, corrosion resistance. The determination of Coefficient of Thermal Expansion (CTE) of MMCs is important to aid its usage in high temperature environment as in the case of automobile combustion chamber. In these applications the stability of the composites over a long period of operation is a critical design considerationPresent work deals with the thermal property evaluation of the Al alloy / alumina metal matrix composite developed using the Stir Casting with chilling route technique. LM 26 Al alloy is being selected as the matrix material as it is a potential alloy for automotive piston applications. Al alloy / alumina MMCs was cast under end chilling technique by dispersing the reinforcement from 6 to 12 wt% the steps of 3% to study the variation in its thermal properties. At the same time chill material is also changed (Copper and MS) for different composition of MMCs cast to study the thermal behavior variations. After casting the required MMC, test specimens were prepared as per the standards to conduct thermal conductivity (K) tests and coefficient of thermal expansion (CTE) tests. Above tests were repeated for different composites containing different weight % of dispersed cast using different chills.

The Design of Composite Materials For Electro-Mechanical and Electro-Thermal Applications.

1983 ◽  
Vol 24 ◽  
Author(s):  
L. E. Cross
Keyword(s):  
Composite Materials ◽  
Figure Of Merit ◽  
Poisson Ratio ◽  
Dielectric Behavior ◽  
Thermal Mass ◽  
Secondary Effects ◽  
Pressure Sensing ◽  
Composite Systems ◽  
Reinforced Composite ◽  
Composite Microstructure

ABSTRACTIn composite materials for electro-mechanical applications, the importance of the mode in which the constituent phases are interconnected (connectivity) was stressed. For the tensor properties of mechanical, piezoelectric, and dielectric behavior, controlling the manner in which fields and fluxes thread through the composite can make orders of magnitude change in the coupled properties.Examples were drawn from piezoelectric ceramic:polymer composites for uniaxial and hydrostatic (hydrophone) pressure sensing where the 1:3 connected transversely reinforced composite can be shown to exhibit a figure of merit more than 103 that of the piezoceramic phase alone. In these systems, the importance of poisson ratio effects in the polymer phase were evident, and some new composite systems where the hydrostatic stiffness of the elastomer phases may be better exploited were considered.In electro-thermal applications such as in pyroelectric composites, the requirements of small-size and low-thermal mass put rigorous limits upon the scale of the composite microstructure. Techniques which achieve the appropriate scaling were described and preliminary data showed strong enhancement of the secondary effects in these composites were presented.

Design and Analysis of Hybrid Fused Filament Fabrication Apparatus for Fabrication of Composites

2021 ◽  
Vol 14 ◽  
Author(s):  
Aniket Yadav ◽  
Piyush Chohan ◽  
Ranvijay Kumar ◽  
Jasgurpreet Singh Chohan ◽  
Raman Kumar
Keyword(s):  
Additive Manufacturing ◽  
Composite Materials ◽  
Design Process ◽  
Low Cost ◽  
Matrix Material ◽  
Fabrication Process ◽  
Layer By Layer ◽  
Fused Filament Fabrication ◽  
Composite Manufacturing ◽  
Tool Paths

Background: Additive manufacturing is the most famous technology which requires materials or composites to be fabricated with layer by layer deposition strategy. Due to its lower cost, higher accuracy and less material wastage; this technology is used in almost every sector. But in many applications there is a need to alter the properties of a product in a certain direction with the help of some reinforcements. With the use of reinforcements, composite layers can be fabricated using additive manufacturing technique which will enhance the directional properties. A novel apparatus is designed to spray the reinforcement material into the printed structures in a very neat and precise manner. This spray nozzle is fully automated, which works according to tool-paths generated by slicing software. The alternate deposition of layers of reinforcement and build materials helped to fabricate customized composite products. Objective: The objective of present study is to design and analyze the working principle of novel technique which has been developed to fabricate composite materials using additive manufacturing. The apparatus is numerically controlled by computer according to CAD data which facilitates the deposition of alternate layers of reinforcement and matrix material. The major challenges during the design process and function of each component has been explored. Methods: The design process is initiated after comprehensive literature review performed to study previous composite manufacturing processes. The recent patents published by different patent offices of the world are studied in detail and analysis has been used to design a low cost composite fabrication apparatus. A liquid dispensing device comprises a storage tank attached with a pump and microprocessor. The microprocessor receives the signal from the computer as per tool paths generated by slicing software which decides the spray of reinforcements on polymer layers. The spraying apparatus moves in coordination with the primary nozzle of the Fused Filament Fabrication process. Results: The hybridization of Fused Filament Fabrication [process with metal spray process has been successfully performed. The apparatus facilitates the fabrication of low cost composite materials along with flexibility of complete customization of composite manufacturing process. The anisotropic behaviour of products can be easily controlled and managed during fabrication which can be used for different applications.

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