Compression and buckling analysis of 3D printed carbon fibre-reinforced polymer cellular composite structures

Lattice structures designed based on triply periodic minimal surfaces (TPMS) gyroid combine ultra-lightweight and high mechanical properties. The specific compression performances and deformation mechanisms of novel gyroid structures made of short carbon fibre reinforced polymer (FRP) composite fabricated by fused deposition modelling (FDM) 3D printing technique are investigated in this study. The effects of the number of unit cells, print direction and relative density on the mechanical properties of 3D printed composite gyroid lattices are studied experimentally and numerically using finite element modelling. The FRP gyroid structures show lower effective elastic modulus when compressively loaded parallel to the FDM print direction due to voids between the 3D printed layers. An empirical formula is proposed to predict the mechanical properties of FRP gyroid lattices as a function of its relative density based on the Gibson-Ashby model. The effect of the slenderness ratio on the compression buckling properties of composite gyroid structures is also studied. A transition from plastic yielding to elastic buckling of the gyroid structures occurs with an increase in the slenderness ratio.