Impact of 3D printed PLA-GF core geometries on the mechanical performance of sandwich structures

Purpose Sandwich structures are highly regarded in engineering for their lightweight design and excellent mechanical properties, but maintaining structural integrity remains a key challenge. This study aims to overcome this limitation by enhancing the shear, compression and impact strength of sandwich structures through the use of fused deposition modeling (FDM) with glass fiber-reinforced polylactic acid (PLA + GF) composites. Design/methodology/approach Three composite core geometries such as trihexagonal, hexagonal and triangular were 3D printed using FDM technology, while unidirectional Kevlar fiber and aluminum layers were used as facing sheets to provide superior impact resistance, energy absorption and corrosion protection. The fabricated sandwich structures were evaluated using low-velocity drop impact, interlaminar shear stress and flatwise compression tests. Findings The trihexagonal composite core exhibited the highest energy absorption, with peak impact energy values of 16.5 J at 600 mm and 27.66 J at 1,100 mm, attributed to its superior internal connectivity and efficient load distribution. Moreover, triangular core achieved the highest peak load of 7,000 N, demonstrating superior load-bearing capacity. Originality/value This research highlights the importance of composite core geometry selection based on application requirements, with the triangular core excelling in strength, the hexagonal core demonstrating superior resilience and the trihexagonal core offering a balanced compromise between the two, making these structures suitable for lightweight, high-performance applications such as automotive bumpers.