Effect of orientation and age on the crack propagation in cortical bone

The crack propagation behavior near the initial crack were studied under the compact tension (CT) fracture toughness experiments test on bovine hip bone joint specimens. The bone specimens were prepared according to ASTM E-399 for plain fracture toughness tests. The specimens were cut from the hip joint both in the longitudinal and transverse direction to the collagen fiber orientation in the bone. The precrack or initial crack "a" were produced parallel and vertical to the lontudinal axis of bone in the longitudinal and transverse specimens respectively. The specimens were tested in the universal testing machine for finding fracture toughness and crack propagation behavior due to different orientation of bone fibers. A camera attached to the machine recorded the crack propagation process. The results show a different crack propagation behavior in longitudinal specimens and transverse specimens. The toughness of the bone consistently changes with age both in longitudinal and transverse direction. Our experimental data matched with the previous published research.