Crack propagation in TPMS scaffolds under monotonic axial load: Effect of morphology.

• Nucleation and propagation of fracture in additively manufactured biomedical scaffolds is important for their proper design and performance. • The tensile and compressive stress-strain states of TPMS periodic structures were studied. • The XFEM method with an original multiple-crack-growth algorithm based on cluster detection was applied to unit cells and representative volumes. • The field of strain-concentration factor allowed introduction of three conditional regions: pre-critical, critical and post-critical states. • The analysis demonstrated considerable differences of mechanical properties and performance of scaffolds with similar levels of porosity. In this paper, the mechanical behaviour and failure of porous additively manufactured (AM) polylactide (PLA) scaffolds based on the triply periodic minimal surfaces (TPMS) is investigated using numerical calculations of their unit cells and representative volumes. The strain-amplification factor is chosen as the main parameter, and the most critical locations for failure of different types of scaffold structures are evaluated. The results obtained are presented in comparison with a multiple-crack-growth algorithm using the extended finite element method (XFEM), underpinned by the experimentally obtained fracture properties of PLA. The effect of morphology of TPMS structures on the pre-critical, critical and post-critical behaviours of scaffolds under monotonic loading regimes is assessed. The results provide an understanding of the fracture behaviour and main risk points for crack initiation in structures of AM-PLA scaffolds based on typical commonly used types of TPMS, as well as the influence of structure type and external load on this behaviour. [ABSTRACT FROM AUTHOR]