Quasi-static tensile and compression performance and failure mechanisms of 3D-printed short fibre-reinforced lattice structures

Additively manufactured lattice structures are increasingly adopted in lightweight and high-strength engineering applications; however, systematic comparative studies that directly link lattice topology, material system, and mechanical performance remain limited. Three lattice structures, honeycomb (HC), Octet (OCT), and I-graph-wrapped package (IWP) were fabricated from carbon fibre-reinforced polymer (CFRP), glass fibre-reinforced polymer (GFRP), and Nylon filaments using the fused deposition modeling (FDM) process. The experimental procedure involved lattice core design, controlled FDM fabrication, and quasi-static mechanical testing to ensure consistent comparison across geometries and materials. Quasi-static tensile and compressive tests were conducted to evaluate how lattice geometry and material affect mechanical performance and failure mechanisms. This study aims to systematically examine the combined influence of lattice topology and material system on the mechanical response of additively manufactured lattice structures, addressing the lack of direct performance comparison among fibre-reinforced and polymeric lattices. The CFRP OCT lattice exhibited 47% and 153% higher tensile load than the CFRP IWP and HC lattice structures, respectively. Compared to the Nylon lattice, the CFRP lattices exhibited 160% (OCT), 102% (IWP), and 31% (HC) greater tensile load. In compression, the CFRP HC lattice outperformed the IWP and OCT lattice structures by 108% and 132%, respectively. The CFRP lattices showed approximately five times (HC), three times (IWP), and four times higher compressive strength than their Nylon counterparts. These performance variations are directly linked to topology-driven load transfer and deformation mechanisms. The superior tensile performance of the OCT lattice structure is attributed to interconnected diagonal and vertical struts, which increase bending stiffness and facilitate efficient load transfer. In contrast, the enhanced compressive performance of the HC lattice structure results from the progressive deformation of its unit cells. These results highlight the potential of fibre-reinforced thermoplastic lattices for optimizing material-to-geometry combinations for advanced industrial applications requiring lightweight, high-strength structures.