Design of lattice structures for trabecular-bone scaffolds: comparative analysis of morphology and compressive...

The study is focused on comparative analysis of different concepts for design of scaffolds for bone tissue engineering based on investigation of their local physical-mechanical properties and response to compression load. Three-dimensional additively manufactured lattice scaffolds with various morphological characteristics and mechanical responses are investigated numerically and experimentally and compared to representative volume elements of real random microstructure of trabecular bone. Prototypes of the studied structures are fabricated with polylactide using a fused filament fabrication technique. Numerical analysis of stress-strain state of scaffolds under compressive loading is performed. The effect of changes in structural morphology parameters on the initiation of stress concentrators as well as nucleation and propagation of fracture is studied. Strain fields on samples' surfaces, captured in the experiments with a micro-digital image correlation technique, are in good agreement with the obtained numerical results. Comparison of the mechanical behaviour and properties of the lattice-scaffold prototypes with those of trabecular bone allows conclusions about selection of their rational morphological structure. Based on the results obtained with the comprehensive analysis, two promising approaches to create scaffolds similar to trabecular bone were identified: models based on a variation of the gyroid surface and ones using Voronoi tessellation with Lloyd's relaxation algorithm.