Influence of the loading rate on the cyclic deformation behaviour and the damage accumulation of cortical bone specimens under three-point bending

The cyclic deformation behavior of cortical bone specimens was characterized by the development of stiffness, the damping, the dynamic modulus and the non-elastic mean strain as functions of the cycle number under bending conditions. Load increase test with interspersed loading cycles with adapted frequency or on a predominantly elastic level showed a distinct development of the hysteresis parameters. The cyclic yield strength was evaluated from the cyclic stress-strain-curves and gave an estimation value for the endurance limit. A statistical analysis would require a much higher number of specimens to consider the high local variation of mechanical properties within one bone but also between bones of different individuals. The bone specimen shows cyclic creep from the beginning of loading and a partial time-dependent recovery during the low loading steps.