Influence of filler topology on the thermal transport of composite materials based on similarity principle modeling: A cross-scale simulation study

Abstract

The thermal conductivity parameter of the materials is a fundamental parameter for thermal design and study of heat transfer processes. In our study, we combined the homogenization theory based on the finite element with the thermal conductivity order-of-magnitude analysis and similarity principle, to construct structural models of fibers, spheres, ellipsoids, sheets, and interfaces, and establish the topology of intermingling and encapsulation of different structures. Combined thermal conductivity calculations of mesoscopic composites and microscopic interface models using finite element and molecular dynamics methods. The anisotropy model of thermal conductivity was established by coordinate transformation. Based on the numerical verification of the reliability of the method, the mechanisms of the influence on the thermal transport of composites were analyzed for parameters such as volume fraction of different structural fillers, structural shape, thermal conductivity ratio, thickness of highly thermally conductive coatings, and spatial orientation distribution. The results showed that the effective thermal conductivity (ETC) of the continuous structural reinforced composite was mainly influenced by the volume fraction of the filler; the modulation of ETC with ellipsoidal particle structure form and distribution mode was comparable to the effect of changing the volume fraction modulation; the mutual fusion between ellipsoids randomly distributed in the plane could effectively enhance the heat transport effect of the composite, and as the volume fraction increased to more than 3%, the heat transport gain from mutual fusion was more obvious; spraying high thermally conductive copper coating on ellipsoidal particles could significantly enhance the ETC of the composites. The present work could provide reference for composites in terms of structural improvement and thermal performance enhancement.