Work to fracture of canine femoral bone

The work-to-fracture of canine femoral bone has been measured using the technique of Tattersall and Tappin (1966). The work required to fracture a specimen in three point bending by slow crack propagation through a triangular cross section is obtained from the load-deformation curve. The area of the resulting fracture surface is measured by macrophotographic techniques, and the work-to-fracture is calculated as work per unit area. The values of fracture “toughness” measured in this way ranged from 5.36 × 10³ J/m² to 1.55 × 10⁴ J/m² in the samples tested with a mean of 9.03 × 10³ J/m² and a standard deviation of 3.27 × 10³ J/m². The work-to-fracture was found to vary with transverse variation in location in the femoral shaft. Scanning electron microscope photographs of the fracture surfaces indicate that the nature of the failure is similar to that of fiber reinforced composite materials. Samples which failed by catastrophic crack propagation were characterized by smooth fracture surfaces and had larger osteons than those which failed by slow crack propagation.