Farid Vakili-Tahami - Associate professor, University of Tabriz
Majid Fatehifar - Graduate MS, K. N. Toosi University of Technology;
Arash Mohammad Alizadeh Fard - PhD student, University of Tabriz;
Naser Firuzan Galhe - Graduate MS, Malek-Ashtar University of Technology;

Vibration is one of the major parameters witch cause failure of rotating components such as shafts. In this work, firstly equation of motion for a rotor shaft coupling system have been developed. It has been assumed that the system has a predefined eccentricity and also it is subjected to lateral radial load. For obtaining governing equations it is has been assumed that the system has three degree of freedom with lateral and rotational vibration. For solving equations Runge-Kutta numerical method is used and by calculating amplitude and mean rotation, mean and alternating shear stresses are obtained. Finally, the safety factor for the shaft is obtained. The results show that fatigue safety factor is significantly affected by eccentricity; so that by increasing eccentricity, fatigue safety factor is reduced significantly. This equations prove that the effect of eccentricity should be taken into account in designing rotating component to prevent any fatigue failure.

Coupling, Rotor, Unbalanced shaft, Rotational vibration, Lateral vibration, Fatigue