Micro-crack propagation on a biomimetic bone like composite material studied with the extended finite element method

Cortical bone contributes to about 80% of the weight of the human skeleton. Along its other properties, cortical bone presents a high resistance to fracture propagation. With this paper the authors aim to model this material using the Extended Finite Element Method (X-FEM) and to understand the mechanism that allow this material to have such a property. A numerical model was developed, considering a biomimetic bone like composite material, modelling the primary anatomical and functional unit of cortical bone, the osteon, as a fiber, the interstitial lamellae as the matrix, and the cement line between them. Different properties were considered for all the above mention materials, and their influence on the micro-crack propagation was studied. The cracks introduced and their geometry allowed the authors to understand why the cracks are arresting their propagation, and why is this material so resistant to crack propagation. The results are presented using the calculated stress intensity factors, for different material and geometries, and also using several brittle fracture crack propagation examples calculated using X-FEM.