Mechanical behavior, energy absorption, and failure mechanism of 3D-printed hexagonal honeycomb core under dynamic and quasi-static loadings

The integration of 3D-printed cellular cores into sandwich composite structures for load-bearing applications opens up innovative design possibilities while improving structural efficiency. However, ensuring effective energy dissipation under impact conditions without compromising structural integrity remains a challenge. This study investigates the energy absorption and failure mechanisms of 3D-printed hexagonal honeycomb sandwich composite structures across three different PLA-based core materials: polylactic acid (PLA), PLA-Carbon, and PLA-Wood, under dynamic and quasi-static loadings. Material characterization was conducted via Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Failure modes were analyzed using optical microscopy. The results show that PLA-Wood composites demonstrated significant improvement in energy absorption, absorbing 9.22 J of energy at an impact energy of 11 J, compared to 8.49 J for PLA-Carbon while under in-plane compression, PLA-Wood recorded an energy absorption of 8.74 J, significantly outperforming PLA-Carbon, which reached only 3.05 J. This improvement is attributed to enhanced interfacial adhesion between the wood filler and the PLA matrix, as confirmed by SEM and FTIR analyses. These findings highlight the critical role of filler compatibility in the structural integrity of 3D-printed sandwich composites, indicating potential applications in the aerospace and automotive industries, where lightweight and durable materials are essential for improving performance.Highlights Dynamic and quasi-static response of 3D-printed hexagonal honeycomb cores. Material interactions affect energy absorption through plastic deformation of cores. PLA-Wood outperforms PLA-Carbon in absorbed energy due to filler compatibility. Dynamic loading causes localized core damage with short elastic recovery. Core failure mechanisms with long elastic recovery vary in quasi-static tests.