Determination of Mode I Fracture Toughness of Cortical Human Bone Using the Dcb Test

The fracture behaviour of human cortical bone was analysed considering a miniaturized version of the Double Cantilever Beam (DCB) test. A specific data reduction scheme based on crack equivalent concept was used to obtain the resistance curves. The definition of the cohesive laws mimicking the fracture process was performed measuring the crack tip opening displacement by digital image correlation during the test. The differentiation of the relation between the strain energy release rate and crack tip opening displacement allows to define the experimental cohesive law. In order to validate the procedure, trapezoidal cohesive laws with bilinear softening were adjusted to the experimental ones. The DCB tests were simulated by finite element analysis including cohesive zone modelling with the adjusted laws. The resulting numerical load-displacement and resistance curves were compared with the numerical ones. Good agreement was obtained which validates the proposed procedure.