A STUDY ON EFFECTIVE THERMAL CONDUCTIVITIES OF PERIODIC COMPOSITES REINFORCED BY UNIDIRECTIONAL LONG FIBERS

Resumo

Due to their excellent physical properties, the composite materials have achieved an
increasing field of industrial applications over the last decades. In many of these applications such
materials are subjected to high thermal gradients which can generate critical stresses and strains. The
magnitude and distribution of the thermal fields induced inside a device or structural element have
strong dependency on the composite microstructure. For the analysis and design of these composite
systems under thermomechanical loading, the effective thermal conductivity of the material is a
property of paramount importance. This effective property depends on many microstructural details,
such as, volume fractions and thermal conductivities of the constituent phases, geometrical shapes and
distribution of the fibers, among others. The present work consists in a theoretical investigation on the
influences of the cross section geometry and volume fraction of the fibers and the contrast between
thermal conductivities of the phases of unidirectional periodic fiber reinforced composites. To develop
the study, a semi-analytical model expressed in terms of Fourier series and based on the thermal
equivalent inclusion strategy is employed. Those mentioned influences are illustrated and discussed
for several numerical examples. Results obtained by other homogenization procedures available in the
literature are also presented to demonstrate the efficiency of the model used in the study.