Evaluation of high-cycle fatigue behavior in compact bones at different loading frequencies

This article presents the evaluation of the high-cycle fatigue behavior in bovine compact bones under different loading frequencies. For this objective, rotating bending fatigue testing has been utilized at 10, 20 and 30 Hz of the loading frequency. Cylindrical specimens were obtained from the 12-month old bovine compact bone, considering both tibia and femur. Obtained experimental results indicated that averaged fatigue lifetimes of femur was higher than the ones of tibia. Besides, the effect of the loading frequency on the high-cycle fatigue lifetime was not significant. In addition, scanning electron microscopy images predicted brittle fractures for bones with cleavage marks. Failure mechanisms for tibia were reported as the separation of the fiber (osteon) and the matrix, micro-cracks insides the matrix, and micro-cracks of the fiber (osteon). Failure mechanisms for femur were presented as the separation of lamella layers and micro-cracks in the lamella bone.