Multi-scale design of the near-zero in-plane thermal expansion property of the woven all-C/C composite honeycomb sandwich structure

The carbon/carbon honeycomb sandwich structure is an ideal solution for ultra-stable satellite platforms. The key to realize its application is to realize near zero thermal expansion design with consideration of different scale characteristics. This study establishes a multi-scale finite element model spanning micro-meso-macro levels to predict thermal expansion behavior of carbon/carbon honeycomb sandwich structures, achieving prediction errors of 11.03 % to the composite and 12.01 % to the sandwich structure. Based on the multi-scale model, optimizations are conducted for weaving patterns and structural dimensions. Analysis of the meso-scale model prediction shows that symmetric plain-woven carbon/carbon composites exhibit superior thermal stability with low thermal strain. When the spreading ratio of elliptical cross-section bundles is increased, the negative thermal strain of the composite is further reduced. Hence, weave structures of the cell wall and the panel are determined. Furthermore, optimal panel thickness, cell wall thickness and cell length combinations of the C/C sandwich structure are identified of (1.5 mm, 0.4 mm, 3 mm), (1.5 mm, 0.4 mm, 5 mm), and (3 mm, 0.2 mm, 3 mm) according to the macro-scale model prediction. Additionally, the configuration of the adhesive layer thickness of the above sandwich structures as 1.18 mm, 0.92 mm, and 0.74 mm respectively consequently achieves the in-plane zero thermal expansion of the sandwich structure. In summary, the zero thermal expansion coefficient design of carbon/carbon honeycomb sandwich structures is achieved through optimization of textile patterns and geometric parameters by multi-scale analysis.