Additive manufacturing (AM) involves the development of complex, lightweight sandwich structures for the automotive and aerospace industries. These structures are essential for load bearing and impact resistance. Nevertheless, there is a significant obstacle of failure under compressive loading, e.g. through brittle fractures and crushing. To address this issue, this study evaluates the compressive properties, energy absorption and failure damage in quasi-static tests (flatwise, in-plane, and flexural) of sandwich composites with 3D-printed hexagonal honeycomb cores of different unit cells (6, 8 and 10 mm) and materials (polylactic acid (PLA), PLA-Carbon and PLA-Wood). The results show that increasing the core density enhances compressive strength, modulus, and energy absorption. An 8 mm unit cell absorbs energy optimally for lightweight structures. In PLA flatwise testing, the 8 mm unit cell absorbed 419.49 J more energy than the 10 mm unit cell. Additionally, PLA-Wood has better mechanical performance than PLA-Carbon due to the better filler with the PLA- matrix. In flatwise testing with an 8 mm unit, PLA-Wood absorbs 214.01 J, while PLA-Carbon absorbs 122.49 J. The failure modes vary depending on tests performed. The study highlights the potential of 3D-printed honeycomb core structures for load-bearing applications in various industries, including aerospace and automotive. Highlights: Quasi-static loading behavior of 3D-printed hexagonal honeycomb cores. Increased core density improves compressive stress, modulus, and absorbed energy. An optimal unit cell size for lightweight 3D printed core structures is 8 mm. PLA-Wood performs better in energy absorption due to filler compatibility. The failure modes are related to the type of quasi-static loads applied.
