On crashworthiness behaviors of 3D printed multi-cell filled thin-walled structures

In this paper, multi-cell filled thin-walled structures were proposed and prepared using fused deposition modeling by carbon-fiber-reinforced polyamide. All structures had the same external hexagonal profile but with different internal circular, hexagonal and triangular filling cells as well as with different filling densities. The crashworthiness behaviors of the structures were studied under quasi-static compression and dynamic impact tests. The effect of fillings on half-wavelength and energy absorption performance of the structures were investigated. Experimental results showed that the specific energy absorption presented an upward trend with the increase of filling density. It presented an increase of 127% for the specimens with high filling density compared with that of low density. The crushing force efficiency increased first and then decreased, and the triangular filled structure with medium filling density showed the highest value of 85.6%. The circular filled structures exhibited higher specific energy absorption than those for hexagonal and triangular filled structures. In addition, compared with quasi-static compression, the specific energy absorption and crushing force efficiency of all structures at high loading velocity decreased by 59% and 39%, respectively. The failure mode of thin-walled structures changed from ductile damage mode to brittle fracture mode, attributing to the strain rate effect of the composite materials. Compared with other popular structures reported in literature, the proposed structures in this study showed merits under quasi-static compression and dynamic impact test.