Numerical strategies for modelling of the degradation process in TPMS-based polymer scaffolds

Artificial porous scaffolds are used in biomedical applications to sustain or replace damaged biological tissues. Embedded into a body, such scaffolds become involved in many physical and biological processes, with degradation and dissolution of the scaffold material being among the most important. Parameters of degradation depends, first of all, on material properties as well as on the properties of the surrounding tissues. It can drastically change the initial mechanical properties of scaffolds. The aim of this work is to investigate the change in effective mechanical properties of polylactide (PLA) porous scaffolds, with morphology based on triply periodic minimum surfaces (TPMS) during degradation and simultaneous compressive loading. Two strategies for modelling of scaffold degradation processes - volumetric and surface degradation - are proposed. Fundamental differences in the proposed approaches are identified and the effects of different types of scaffold morphology on changes in effective elastic properties evaluated. The present study may be useful for design of optimal TPMS scaffold structures taking into account the effect of degradation process on their structural integrity.