Influence of infill pattern and layer height on surface characteristics and fatigue behavior of FFF-printed PEEK

Abstract

PolyEther Ether Ketone (PEEK) is a leading thermoplastic biomaterial renowned for its exceptional overall properties and suitability for processing via Fused Filament Fabrication (FFF) Additive Manufacturing (AM). Despite its widespread use in industries, its fatigue behavior remains a critically underexplored aspect. This study aims to investigate the fatigue behavior of FFF-produced PEEK, considering variations in infill pattern (triangular or rectilinear) and layer height (0.15 mm or 0.25 mm). Fatigue tests revealed a significant influence of the infill pattern on fatigue behavior, with the rectilinear pattern outperforming the triangular one. Layer height had a negligible effect when paired with rectilinear infill. Specimens with rectilinear patterns exhibited superior fatigue performance, achieving infinite fatigue life at maximum applied stress around 70% of ultimate tensile stress. Surface roughness assessment and fracture surface analysis at scanning electron microscope enhanced the interpretation of the results. This pioneering study lays the groundwork for future research in design for AM.