Influence of layup configuration on through-thickness thermal conductivity of CFRP composites: Based on effective heat transfer volume theory and predictive modeling

Cross-ply layup enhances CFRP through-thickness thermal conductivity by 5.46–23.40% without fillers. • Novel “effective heat transfer volume” theory explains enhanced Z-direction conduction pathways. • Predictive model for Z-direction heat flux with <±4% error captures key interactions. The thermal performance of carbon fiber reinforced polymer (CFRP) composites is critical for engineering thermal management applications. This study investigates how layup configurations influence through-thickness (Z-direction) thermal conductivity and elucidates the underlying mechanisms. Thermal conductivity was measured using the laser flash method and the transient plane source technique. These measurements were validated through water droplet evaporation experiments and infrared thermal imaging. Cross-ply laminates exhibited higher Z-direction thermal conductivity than unidirectional laminates, with increases of 5.46% in thin specimens and 23.40% in thick specimens. Through finite element analysis (FEA), the regulation of heat flow distribution by carbon fibers in the resin matrix was investigated. Based on these results, the “effective heat transfer volume” concept was proposed for the first time. Specifically, the spatial arrangement and distribution of fibers influence the resin-matrix-dominated heat conduction pathways. At fiber spacings of 1–13 μm, cross-ply and angle-ply layups exhibit higher through-thickness thermal conductivity than unidirectional layups due to an increased effective heat transfer volume. Mathematical models were developed to predict the Z-direction heat flux for unidirectional, cross-ply, and angle-ply (±45°) configurations, based on the thermal conductivities of the carbon fibers and resin matrix as well as the fiber volume fraction. The models demonstrate excellent fit (R 2  > 0.98) and high accuracy (errors < ±4%). These findings provide a theoretical foundation and practical guidance for structural optimization of CFRP composites in thermal management, such as electric vehicle battery encapsulation and 5G base station heat dissipation. Download: Download high-res image (386KB) Download: Download full-size image