Exact relation between the thermal and electroelastic moduli of composite materials with emphasis on two-phase laminates

1993 ◽  
Author(s):  
Martin L. Dunn
Keyword(s):  
Composite Materials ◽  
Two Phase ◽  
Exact Relation

scholarly journals Efficiency of the Needle Probe Test for Evaluation of Thermal Conductivity of Composite Materials: Two-Scale Analysis

2014 ◽  
Vol 36 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Dariusz Łydżba ◽  
Adrian Różański ◽  
Magdalena Rajczakowska ◽  
Damian Stefaniuk
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Numerical Simulations ◽  
Conductivity Measurement ◽  
Scale Analysis ◽  
Equivalent Conductivity ◽  
Inclusion Type ◽  
Two Phase ◽  
Needle Probe ◽  
Probe Test

Abstract The needle probe test, as a thermal conductivity measurement method, has become very popular in recent years. In the present study, the efficiency of this methodology, for the case of composite materials, is investigated based on the numerical simulations. The material under study is a two-phase composite with periodic microstructure of “matrix-inclusion” type. Two-scale analysis, incorporating micromechanics approach, is performed. First, the effective thermal conductivity of the composite considered is found by the solution of the appropriate boundary value problem stated for the single unit cell. Next, numerical simulations of the needle probe test are carried out. In this case, two different locations of the measuring sensor are considered. It is shown that the “equivalent” conductivity, derived from the probe test, is strongly affected by the location of the sensor. Moreover, comparing the results obtained for different scales, one can notice that the “equivalent” conductivity cannot be interpreted as the effective one for the composites considered. Hence, a crude approximation of the effective property is proposed based on the volume fractions of constituents and the equivalent conductivities derived from different sensor locations.

An Orthotropic Integrated Flow-Stress Model for Process Simulation of Composite Materials—Part I: Two-Phase Systems

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Sina Amini Niaki ◽  
Alireza Forghani ◽  
Reza Vaziri ◽  
Anoush Poursartip
Keyword(s):  
Composite Materials ◽  
Flow Stress ◽  
Interactive Effect ◽  
Fluid Phase ◽  
Solid Material ◽  
Material System ◽  
Two Phase ◽  
Stress Development ◽  
Thermoset Resin ◽  
Three Phase

An integrated flow-stress (IFS) model provides a seamless and mechanistic connection between the two distinct regimes during the manufacturing process of composite materials, namely, fluid flow in the pregelation stage of the thermoset resin and stress development in the composite when it acts as a solid material. In this two-part paper, the two- and three-phase isotropic IFS models previously developed by the authors are extended to the general case of composite materials with orthotropic constituents. Part I presents the two-phase, fluid-solid, orthotropic model formulation for the case where the fluid phase solidifies during the course of curing. Part II extends the orthotropic formulation to a three-phase model that includes a gas phase as the third constituent of the composite material system. A broader definition of material properties in poroelasticity formulation is adopted in the development of the general orthotropic formulation. The model is implemented in a two-dimensional (2D) plane strain u-v-P finite element (FE) code and its capability in predicting the flow-compaction behavior and stress development is demonstrated through application to a case study involving an L-shaped unidirectional laminate undergoing curing on a conforming convex tool. Comparison of the results with those obtained from sole modeling of the stress development reveals the importance of capturing the simultaneous and interactive effect of the mechanisms involved during the entire process cycle using an IFS modeling approach presented in this paper.

Use of Composite Materials for FDM 3D Print Technology

2016 ◽  
Vol 862 ◽  
pp. 174-181 ◽  
Author(s):  
Jiří Šafka ◽  
Michal Ackermann ◽  
Jiří Bobek ◽  
Martin Seidl ◽  
Jiří Habr ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Fused Deposition Modelling ◽  
Two Phase ◽  
3D Print ◽  
Fused Deposition ◽  
Thermoplastic Matrix ◽  
Constant Diameter ◽  
Phase Systems ◽  
Progressive Technology

This article deals with specific polymer composites modified for the Fused Deposition Modelling (FDM) which is a 3D print technology. These two phase systems involve thermoplastic matrix filled with natural fibres. The crucial demand of this progressive technology is put on the accuracy of the semi-product formed into the filament shape. To reach the smooth production of 3D prototypes the filament should have a constant diameter. In the article, individual steps of the polymer composite pelletization and following pre-processing and processing activities are described. Among these steps the extrusion of the filaments belongs and subsequent print test on “RepRap” device accompanied by optimization of building parameters. Tensile specimens were chosen for print with regard to maps mechanical properties of this newly developed material which was the final stage of this work. Tensile test curves were then compared with those graphs which can be found for the material produced by conventional technologies such as injection moulding.

Determination of closed form expressions of the second-gradient elastic moduli of multi-layer composites using the periodic unfolding method

2018 ◽  
Vol 24 (5) ◽  
pp. 1475-1502 ◽  
Author(s):  
Jean-François Ganghoffer ◽  
Gérard Maurice ◽  
Yosra Rahali
Keyword(s):  
Composite Materials ◽  
Closed Form ◽  
Elastic Moduli ◽  
Gradient Elasticity ◽  
Constitutive Law ◽  
Two Phase ◽  
Linear Elastic ◽  
Second Gradient ◽  
Two Phases ◽  
Unfolding Method

The present paper aims at introducing a homogenization scheme for the identification of strain–gradient elastic moduli of composite materials, based on the unfolding mathematical method. We expose in the first part of this paper the necessary mathematical apparatus in view of the derivation of the effective first- and second-gradient mechanical properties of two-phase composite materials, focusing on a one-dimensional situation. Each of the two phases is supposed to obey a second-gradient linear elastic constitutive law. Application of the unfolding method to the homogenization of multi-layer materials provides closed form expressions of all effective first- and second-gradient elastic moduli as well as coupling moduli between first- and second-gradient elasticity. A comparison between the unfolding method and the method of oscillating functions shows that both methods, despite their differences, deliver the same effective second-gradient elastic constitutive law for stratified materials.

Interaction of Waves in Solid Mixtures

1999 ◽  
Vol 52 (2) ◽  
pp. 35-74 ◽  
Author(s):  
J. J. Rushchitsky
Keyword(s):  
Composite Materials ◽  
Wave Interaction ◽  
Nonlinear Acoustics ◽  
Review Article ◽  
Two Phase ◽  
Interaction Of Waves ◽  
Simple Waves ◽  
Mechanics Of Materials ◽  
Physical Effects ◽  
Main Effects

The focus of this review article is on analytical procedures and physical effects which are characteristic of the theory of nonlinear and simple waves in materials. Waves are supposed to propagate in composite materials, which are modeled as solid two-phase mixtures. It is shown how procedures of wave interaction investigations in nonlinear acoustics, optics and radiophysics are applied to nonlinear mechanics of materials with a microstructure. Main effects of the interactions of waves in composite materials: new harmonics generation, self-generation, evolution and distortion, synchronization, breakdown instability, etc are commented upon. This article is proposed not only for specialists in wave theories; therefore it contains some facts which are obvious for researchers working in the field of waves. Many portions of this review are described in more detail in a book (Rushchitsky and Tsurpal (1998), 377 pages). This review article contains 286 references.

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