Modelling of the effective thermal conductivity of composites reinforced with fibers and particles by two-step homogenization method

Abstract

Fiber-particle-reinforced hybrid composites are widely applied in many fields. Knowing their effective thermal conductivity (ETC) is essential. This paper first calculates the ETC of different fillers reinforced composites by the Lattice Boltzmann method and proposes a correlation for the ETC of fiber-reinforced composites based on Lewis-Nielson's model with an average deviation of less than 2.7%. In what follows, a two-step model for the ETC of fiber-particle reinforced composite is proposed by combining the correlations for fiber-reinforced composites and particle-reinforced composites based on the two-step homogenization method. The results show that the two-step homogenization method could accurately predict the ETC of fiber-particle reinforced composites with randomly arranged fibers; however, a reasonable choice for the phase pair is crucial for this method. In addition, the accurate combinability of Lewis-Nielson's model for particle-reinforced composites with the parallel model and Perrins et al.'s model could accurately predict the ETC of fiber-particle-reinforced composites with aligned fibers with a maximum deviation of less than 3.9%. Finally, the two-step homogenization method is also validated for the particle-particle reinforced composites, and the phase pair selection hardly influences the results. However, this method fails to predict the ETC of fiber-fiber reinforced composites no matter how to choose the phase pair.