Functional grading of polymer triply periodic minimal surface structures for enhanced compressive performance and lightweight design in additive manufacturing

This study explores the fabrication and performance of functionally graded gyroid lattice structures produced by fused deposition modeling (FDM) using polylactic acid (PLA). Lattice thicknesses were varied from 1 mm to 5 mm across five series to optimize weight reduction and compressive strength. Thermogravimetric (TGA) and differential thermal (DTA) analyses indicated a PLA degradation point between 350-400 °C, with peak decomposition near 400 °C. Hardness tests averaged 77.6 Shore-D, showing consistent mechanical properties across graded samples. Compression tests revealed three deformation stages: linear elasticity, elastic-plastic transition, and densification. Results showed that increased lattice thickness correlated with higher initial peak stress, ranging from 6.8 MPa at 1 mm to 25.3 MPa at 5 mm, indicating enhanced structural robustness. The study demonstrates that functionally graded lattice structures can be tailored for specific mechanical needs, supporting their suitability for lightweight, load-bearing applications in fields such as automotive and aerospace. The successful production of complex gyroid structures using FDM confirms the method’s capability in creating advanced, structurally efficient lattice designs.