Abstract: For the rotor system, the existence of the crack on the shaft influences the stiffness of the system, and in further the dynamic performance. General stiffness models are summarized for the cracked shaft and gives out two new methods to obtain the stiffness. Because of the different theories among the general models and two new methods, the opening areas of the crack on the shaft and the stiffness of the shaft will be different accordingly. Through comparing with the experimental stiffness, it is found that the stiffness obtained by one of the new methods is more useable.

Key words: Neutral axis, Rotor, Stiffness, Stress intensity factor