“…Studies carried out on bending vibration of the rotors of induction motors include the analysis of unbalanced electromagnetic forces due to static eccentricity (Bradford, 1968), dynamic eccentricity (Belmans et al, 1987;Iwata and Sato, 1997;Yang et al, 1999a), effects of slot and skew (Dorell, 1996), and phase voltage unbalance (Kanzaki et al, 1994), etc. Those studies basically focus on experiments and analytical evaluation for electromagnetic forces, or consider only the condition of unstable vibrations for simple systems with one or two degrees of freedom.…”