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 lat-tice, 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 degrees/135 degrees. 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 x 10-6/degrees C, based on the planar com-posite 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/cm3 and an effective CTE of 0.0173 x 10-6/degrees 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.