Evaluation of bone cohesive laws using an inverse method applied to the DCB test

The double cantilever beam test was used to measure the mode I fracture properties of bovine cortical bone. Hydrated and dehydrated bone was used as testing material with the objective to analyze the influence of water on bone fracture toughness. Additionally, water influence on the elastic modulus and on the material brittleness was also assessed by means of the flexure and microhardness Vickers tests, respectively. Two different data reduction schemes were utilized to determine the Resistance-curve of hydrated and dehydrated bone, both allowing the measurement of bone fracture toughness. Cohesive laws describing fracture behavior were determined from measured fracture energies through an inverse method, based on a developed genetic algorithm combined with finite element simulation of the double cantilever beam test. Two different types of laws were identified owing to dissimilar fracture behavior observed for the hydrated and dehydrated young bovine bone. It was verified that water plays a fundamental role in which concerns the material ductility which reflects on completely different fracture mechanisms.