Effects of Initial Crack Length and Specimen Thickness on Fracture Toughness of Compact Bone.

Abstract

This paper deals with the determination of fracture mechanics parameters, such as critical stress intensity factor, Kc, and critical strain energy release rate, Gc, of compact bone. Haversian bone samples taken from fresh bovine femurs were machined into small compact tension (CT) specimens with various initial crack lengths and thicknesses, and then tested under quasi-static mode I loading condition at room temperature. Factor Kc was determined following the ASTM standard E399-90, and the compliance method was used for the determination of Gc. The values of Kc and Gc were larger in the specimens with transversely oriented initial cracks than in those with longitudinally oriented initial cracks. Both Kc and Gc were dependent on initial crack length as well as specimen thickness, and these fracture characteristics could be interpreted by a hypothesis based on the observation of damage accumulation, or microcracking ahead of the main crack front.