Mechanical degradation model of porous magnesium scaffolds under dynamic immersion

A new generation of bone scaffolds incorporates features like biodegradability and biocompatibility. A combination of these attributes will result in having a temporary bone scaffold for tissue regeneration that mimics the natural cancellous bone. Under normal conditions, scaffolds will be gradually eroded. This surface erosion occurs due to the immersion and the movement of bone marrow. Surface erosion on bone scaffolds leads to changes of the morphology. The mechanical response of the scaffolds due to the surface erosion is not fully understood. The aim of this study is to assess the influence of the dynamic immersion condition on the degradation behaviour and mechanical properties of porous magnesium. In the present work, load-bearing biomaterial scaffolds made of pure magnesium are immersed in simulated body fluids (SBF) with a certain flow rate. Samples with different porosities are subjected to tomography and are used to develop virtual 3D models. By means of numerical simulations, the mechanical properties, for instance, elastic modulus, plateau stress, 0.2% offset yield stress and energy absorption of these degraded samples are collected. The findings are then validated with the values obtained from the experimental tests. Finite element method enables the study on the failure mechanism within the biomaterial scaffolds. The knowledge of how weak walls or thin struts collapsed under compressive loading is essential for future biomaterial scaffolds development. Results from the experimental tests are found in sound good agreement with the numerical simulations.