Abstract
Cortical bone has anisotropic mechanical properties depending on the hierarchal structure of the tissue observed on multi-scales. Microscopic structure of bone tissue contains micro structural defects such as Haversian canal, osteocyte, boundary of osteons and microcracks. This study focused on fracture behaviors of cortical bone tissue including micro-nano scale structural defects. A compact-sized loading machine for Charpy impact tests was developed to measure the fracture toughness of bone specimens. The cortical bone specimens of 3 x 3 x 30 mm were prepared from a shaft of bovine femur. The differences relating the anisotropy of each specimen were observed in the fracture toughness and the fracture surfaces. The fracture energy values of the bone axial specimens were greater than of the circumferential specimens. The bone axial specimens were demineralized in EDTA solution for several days. The demineralized specimens showed different fracture surfaces and different fracture energy compared with intact specimens. The 48 hour demineralized specimen required the highest energy for fracture. The long term of 1 month demineralized specimen had high bendability and the specimen was not fractured in the impact tests.
