Mechanical properties of additive-manufactured hydroxyapatite porous scaffolds and follow-up of damage process under compression loading

In this work, the mechanical response and the damage process during compressive loading tests of hydroxyapatite scaffolds processed by stereolithography and designed for biomedical applications were investigated. Damage is followed by acoustic emission monitoring, Scanning Electron Microscopy observations at different loading stages and by In-situ X-ray tomography. A significant and progressive damage evolution is observed at stress value superior to 25 MPa. The cracks responsible for the damage are initiated from the edge of the sample and propagate parallel to the applied force, which explains the small variation of the Young's modulus, initially of 85 GPa, during loading/unloading sequences. Finite element analysis confirmed that the stress is non-uniform and maximum at the edge of the sample, which confirms the scenario of damage evolution.