Vibrations are an inherent part of all rotating machinery. Residual mass imbalance and dynamic

interaction forces between the stationary and rotating components, which are practically impossible to

eliminate, cause these vibrations. The challenge is to identify the source of vibration and control it to

within reasonable limits. Because of economic advantages, the trend in industry has been to move

towards high speed, high power, lighter and more compact machinery. This has resulted in machines

operating above their first critical speeds, which was unheard of in the past. The new operating

parameters have required concurrent development of vibration technology without which it is not


an essential phenomenon, which could be used to assess the performance, durability, and reliability of

rotating machinery.