Rotating bending fatigue performance of FFF-fabricated PLA HD and ABS polymers: experimental characterization, numerical modeling and critical infill influence configuration

Purpose This study aims to quantify the rotating-bending fatigue performance of fused filament fabrication (FFF) polylactic acid (high density) (PLA HD) and ABS and validate a predictive framework to support design and life assessment of fatigue-critical AM components. Design/methodology/approach The authors combined quasi-static testing (American society for testing and materials D638/D695), rotating-bending fatigue (15–45 MPa, 10–20 Hz) and FE modeling (ABAQUS + fe-safe with ductile damage). Specimens used two architectures: 20% grid infill (A) and 100% infill (B). Surface roughness and frequency sensitivity were assessed. Findings Configuration B improved tensile performance (PLA HD: 57.7 MPa strength, 2.98 GPa modulus; ABS: 25.0 MPa strength) and extended fatigue life by 2.5–4.2×. Endurance limits were 20 MPa (PLA HD) and 15 MPa (ABS). Surface finishing to Ra < 10µm increased fatigue life by 25%–40%. The model achieved R > 0.95 for tensile response and factor-of-two compliance of 92% (PLA HD) and 88% (ABS) for fatigue prediction. Originality/value The authors provide rotating-bending S–N curves with statistical bounds for FFF PLA HD/ABS, quantify architecture and surface-finish effects, and deliver a validated, orientation-aware predictive workflow. These results translate into design allowables and process controls for safer deployment of AM polymers in bending-dominated, high-cycle applications.