Dynamics of Rotor-Bearing Systems

In many industries the demand for high power and high speed together with uninterrupted and reliable operation is increasingly important. The accurate prediction and control of dynamic behaviour (unbalance response, critical speeds and instability) is another vital requirement. The bearings clearly constitute a vital component in any turbomachine. The dynamic behaviour of rotary machinery can be influenced by the design of the bearings. The design can be altered by changing the geometrical and material properties of the bearing and the properties of the lubricant. Finite element methods (FEM) are at present very widely used in predicting the dynamics of rotary machinery.

Fault Diagnosis of Rotary Machinery

Monitoring and diagnosis of rotating machinery is receiving an increasing interest since evidences revealed the severity of the undetected faults. The present day requirement for ever-increasing reliability in the field of rotor dynamics is now more important than ever before and continues to grow constantly. Because of progress made in engineering and materials science, rotating machinery is becoming faster and lighter, as well as being required to run for longer periods of time. All of these factors mean that the detection, location and analysis of fault play a vital role in the field of rotor dynamics for minimizing the overall maintenance cost and time. The methods available for condition monitoring can be categorised as vibration signal analysis, model-based techniques and statistical analysis.

Experimental Modal Analysis

Modal Analysis as an engineering tool was first applied around 1940, in the search for a better understanding of aircraft behavior. In early stages, most of the applications of the Modal Analysis were concerned with trouble shooting, dominated by a physical approach to the understanding of vibration problem. More recently development and verification of modal models have been of higher concern, involving a more integrated physical and mathematical approach. In general, the main objectives of Modal Analysis are validation, correction and updating of analytical dynamic models; development of experimentally based dynamic models; structural modification and damage detection; model integration with other areas of dynamics such as acoustics, fatigue, etc. In short, Modal Analysis primarily is an experimental tool to develop reliable dynamic models that may be used with confidence for further analysis.