Equivalent inclusion method for steady state heat conduction in composites

Thermal conductivity experiments are reported on unidirectional composites over the temperature range −150 to 130 ° C. Results for R-glass/Fibredux 914 specimens, and for carbon fibre GY-80/Code 69 resin specimens, in directions parallel and perpendicular to the fibre directions have been interpreted using standard theories. Experiments were also made on specimens in which the carbon fibres made angles of 30 °, 45 ° and 60 ° to the temperature gradient. An attempt was made to understand these data using a finite difference model.

Thermal conductivity measurements of some glass fibre- and carbon fibre-reinforced plastics

By applying the fundamental definition of thermal conductivity to a unit cell of an orthogonal fiber-reinforced composite material in a one-dimensional heat flow, one can readily deduce simple mathematical expressions for the equivalent thermal conductivity for the composite material. Such expressions can serve as useful guides for materials development.

Equivalent Thermal Conductivity of Two- and Three-Dimensional Orthogonally Fiber-Reinforced Composites in One-Dimensional Heat Flow

The aim of present study is to investigate the effective thermal properties of composite material via micromechanical modeling of the composite material as a heterogeneous material. These properties mainly include the thermal diffusivity and the thermal conductivity of composites. For this purpose, a definition is presented for effective thermal diffusivity for heterogeneous materials based on heat diffusion rate into the material in a transient heat transfer. A micromechanical model based on the Representative Volume Element (RVE) is presented for modeling the heat conduction in the fibrous composite materials. An appropriate heat transfer problem for the RVE is defined so that by the analogy of the numerical results the effective properties of the RVE can be estimated. A numerical method is employed to analyze the steady-state and transient heat flux and temperature in the RVE. To validate the model, the predictions of present model are compared with results of analytical method, FEM and some available experimental data in the open literature. The effective thermal conductivity and thermal diffusivity are then obtained for fibrous composites via the present micromechanical model. The SiC/Ti, SiC/Ti6%Al4%V and Glass/Epoxy composites with various fiber volume fractions are considered in this study.

Evaluation of effective thermal diffusivity and conductivity of fibrous materials through computational micromechanics

Purpose – The purpose of this paper is to present a micromechanical model based on a new truly local meshless method for analysis of heat transfer in composite materials.Design/methodology/approach – The presented meshless method is based on the integral form of energy equation in the sub‐particles in the material. In the presented meshless method due to elimination of domain integration the computational efforts are decreased substantially.Findings – Numerical results are presented for temperature distribution, heat flux and thermal conductivity. Numerical results show that the presented meshless method is simple, effective, accurate and less costly method in micromechanical modeling of heat conduction in heterogeneous materials.Research limitations/implications – A small area of the composite system called representative volume element is considered as the solution domain. The fully bonded fiber‐matrix interface is considered and contact thermal resistant is neglected from the fiber matrix interface and...

Heat transfer in composite materials using a new truly local meshless method

The effective thermal conductivity of a unidirectional composite was determined. Inner structure of the composite was approximated by symmetric, rectangular arrangement of fibers. The composite thermal con ductivity was calculated with the use of different theoretical methods and compared to experimental data obtained from a model of the composite and the composite itself. Good agreement was found between theory and experiment. Temperature fields in the composite were also calculated. The results of the effective thermal conductivity occurred to be lower than the analogical values obtained by Adams and Doner. It was found that for isotropic composite having up to 50% fiber volume fraction, Hashin and Rosen's formula for "random arrangement" of fibers could be successfully used. Two pairs of bounds on the composite thermal conductivity were studied. Each of them was found to be narrower for different range of fiber volume fraction.

Wieslaw Gogó

Papers

Some Investigations of Effective Thermal Conductivity of Unidirectional Fiber-Reinforced Composites