Lightweight 3D carbon fibre reinforced composite lattice structures of high thermal-dimensional stability

In this study we develop and investigate a novel lightweight 3D composite lattice structure of high thermal-dimension stability, i.e., with zero coefficient of thermal expansion (CTE). First, a base planar composite lattice, comprised of a continuous carbon fibre reinforced polyamide (CCF/PA) central cross-lattice and four short carbon fibre reinforced polyamide (SCF/PA) outer strips for good thermal-dimensional stability, was additively manufactured in a rotated cross-ply sequence, i.e., at alternative 45°/135°. Experiments were performed to validate an effective numerical model where effective thermo-elastic properties were applied; the results proved the effective numerical model's accuracy and efficiency. Second, a novel 3D composite lattice structure was developed and calculated, exhibiting a negative effective CTE at −0.18 × 10/°C, based on the planar composite lattices. Then, parametric analysis was performed to investigate the effects of geometric parameters on the effective CTE and density. Finally, lightweight optimisation was conducted with a constraint of effective CTE as zero. The results show that the optimal 3D composite lattice structure can achieve an effective density of 0.0266 g/cm and an effective CTE of 0.0173 × 10/°C, which are 15.3 % and 90.39 %, respectively, improved over the initial 3D composite lattice. The outcomes proved the effectiveness of the design in achieving a novel lightweight 3D composite lattice structure of high thermal-dimensional stability.