Numerical and experimental study on anisotropic heat transfer behaviors of quartz fabric composite preforms: Multiple micro-scale models method

This paper presents a comprehensive study on anisotropic heat transmission behaviors in quartz fiber fabrics. Considering the random distribution characteristic of fibers within the yarn, an innovative two-scale finite element method (tFEM) is introduced, incorporating multiple micro-scale fiber models (MMFM) based on scanning electron microscope (SEM) observations. MMFM are divided into 8 distinct models to capture intricate fiber arrangements. The macro-scale fabric model is constructed based on the geometric structure analysis by Micro-CT technology. Both micro- and macro-scale models are assembled with the air matrix to form the two-phase composite model. The Hot-Disk thermal analysis instrument is applied to measure the anisotropic thermal conductivity (ATC). Numerical results from MMFM shows more excellent agreements with the experimental ones at 3D orthogonal directions of fabrics, i.e., the error rates of the thermal conductivity in the warp, weft and thickness directions between numerical and experimental methods are all less than 3%, which indicates the tFEM including MMFM in this paper is more accurate than the tFEM including OSMFM. In addition, the temperature distribution and heat transmission differences due to fiber arrangements are simulated and illustrated through the MMFM. Afterwards, temperature drop and isothermal characteristics are demonstrated in this study. Highlights: Effects of fiber arrangements on steady heat transfer behaviors at micro-scale are illustrated. Isothermal and temperature-drop characteristics at micro- and macro-scale are simulated and studied. The transverse isotropy of thermal conductivity at micro-scale and the anisotropy of that at macro-scale are revealed.