Rotor dynamics is the study of rotating machines and has a very important part to play throughout the modern industrial world. Rotating machinery is used in many applications such as Turbo machinery, Power stations, Machine tools, Medical equipment, etc. Failure of machinery in applications such as aero engines, turbo-machines, space vehicles, etc. creates enormous repair costs and more importunately may put human life in danger.
Rotor dynamics is a collective terms for rotating machines and can be split into the sub groups that make it up. These are rotating shafts, bearings, seals, out of balance systems, instability and condition monitoring. The Contact of fluid with the rotating shaft leads to unwanted Vibrations and several other defects.
Vibration is considered with the oscillating motions of the bodies and the forces associated with them. Objectionable vibrations in a machine may cause the loosening of the parts, its malfunctioning or its eventual failure. The study of the vibration is to determine its effect on the performance and safety of the system under consideration. The performance of many instruments depends on the proper control of the vibration characteristics of the devices. Energy may be stored in the mass and spring, and dissipated in the damper in the form of heat. The mass may gain or lose kinetic energy in accordance with the velocity change of the body. The spring possesses elasticity and is capable of storing the potential energy under deformation.
When the excitation is oscillatory, the system is forced to vibrate at the excitation frequency. If the frequency of excitation coincides with one of the natural frequencies of the system, a condition of resonance is encountered, and dangerously large oscillations may result. The failure of the major structures such as bridges, buildings or airplane wings is an awesome possibility under resonance. Thus, the calculation of the natural frequencies is of major