Fracture and fatigue crack growth behaviour of additively manufactured material

Abstract

This thesis explores the fracture and fatigue crack growth behaviour of 3D-printed Polylactic Acid (PLA) specimens produced via Fused Deposition Modelling (FDM). As additive manufacturing (AM) advances, understanding the mechanical reliability of printed components under cyclic loading and fracture conditions is critical yet under-researched. The study investigates the impact of varying infill densities of 25%, 50%, and 100% with a honeycomb infill pattern on the tensile properties, fatigue crack growth rate (FCGR) and fracture toughness of PLA specimens. Mechanical testing, conducted according to ASTM standards, reveals significant correlations between infill density and mechanical performance. Higher infill densities result in increased tensile strength, enhanced fracture resistance, and distinct fatigue behaviour, emphasizing the influence of the internal structure on material properties. The findings provide essential insights into optimizing FDM processes for critical applications, addressing the research gap in the mechanical characterization of AM materials. This work contributes to the broader application of FDM-printed PLA in industries requiring reliable performance under diverse loading conditions, such as aerospace, biomedical, and automotive engineering.