Design guidelines for FDM-processed PEEK lattice structures: mechanical properties, energy absorption under compressive loading, and process-induced defects

Abstract Additive manufacturing of polyetheretherketone (PEEK) through fused deposition modeling (FDM) enables the fabrication of complex lattice structures for aerospace and biomedical applications. However, a systematic understanding of topology-performance relationships in FDM-processed PEEK components remains limited. This investigation addresses how relative density (10–30%) and lattice topology (Cross3D, gyroid, and octet) influence the compressive mechanical behavior and energy absorption characteristics of FDM-fabricated PEEK lattice structures. Cubic test specimens (25 mm edge length) were manufactured using three distinct lattice geometries across varying relative densities. Specimens were subjected to quasi-static compression testing under standardized conditions. Mechanical characterization included determination of Young’s modulus, yield strength, and energy absorption properties. Scanning electron microscopy analysis identified topology-dependent, process-induced manufacturing defects. Gyroid structures demonstrated superior mechanical performance, achieving a Young’s modulus of 278 MPa and yield strength of 17.9 MPa at 30% relative density, corresponding to efficiency factors of 27.2 and 50.2%, respectively. Octet structures exhibited comparable stiffness (270 MPa) but lower yield strength (16.26 MPa), while Cross3D structures showed substantially reduced performance (100 MPa Young’s modulus, 1.3 MPa yield strength). Energy absorption analysis revealed the superior performance of gyroid structures, achieving 22.8 J/g normalized energy to densification compared to 17.8 J/g for octet and 7.8 J/g for Cross3D configurations. SEM analysis enabled an understanding of how structural architecture and its consequent toolpath strategies affected material extrusion quality. The results and SEM analysis revealed strong sensitivity of PEEK extrusion to toolpath directional changes, sudden material flow interruptions and restarts, as well as travel movements between different deposition regions that cause stringing defects. This study establishes that lattice topology significantly influences the mechanical performance of FDM-processed PEEK components, with gyroid structures providing optimal combinations of stiffness, strength, and energy absorption for lightweight, high-performance polymeric components in engineering applications.