In situ loading and x-ray diffraction quantification of strains in hydroxyapatite particles within a 3D printed scaffold

A 3D printed scaffold consisting of a composite with very high volume fraction of particulate hydroxyapatite (hAp, 74 vol.%) and small volume fraction of poly-lactic-co-glycolic acid (26 vol.%) was loaded in compression, and the internal strains in the hAp phase were measured by high-energy x-ray diffraction. Diffraction patterns were recorded at multiple positions in the scaffold at cross-head displacements of 0, -0.52 and -0.62 mm (2.0 mm total scaffold height). The 00.2 and 21.0 hAp strains never exceeded 2 × 10⁻⁴, and most positions showed strains ≤ 1 × 10⁻⁴, which was the magnitude of the experimental uncertainty.