The open cracked rotors are experimentally investigated in order to look into the possibillity to detect open cracks in rotors by monitoring the vibration responses. The whirl orbit patterns of the open cracked rotors with the crack width, depth and location varied are compared with that of the noncracked rotor, as the rotation speed increases. In particular, harmonic response analysis is performed to clarify the response changes due to the presence of various cracks. The experimental results show that the whirl orbit patterns significantly change as the crack depth varies whereas the changes are hardly detectable as the crack width varies. It is also observed that the 2x and 3x responses remarkably increase as the crack depth increases.
