Vibration Problems in Machines

Arthur W. Lees, BSc, PhD, DSc, CEng, CPhys, FIMechE, FInstP, LRPS, joined the Central Electricity Generating Board, London, UK, after completing his PhD. Following a sequence of positions, he was appointed head of the Turbine Group for Nuclear Electric Plc, UK. In 1995, he moved to Swansea University, UK, where he is currently professor emeritus. An active researcher, Professor Lees is a regular reviewer of many technical journals, a fellow of the Institution of Mechanical Engineers and the Institute of Physics, and a chartered engineer and physicist. He has served on the editorial boards of the Journal of Sound and Vibration and Communications in Numerical Methods in Engineering, and was a member of the Council of the Institute of Physics, 2001–2005.

Introduction
Monitoring and Diagnosis
Mathematical Models
Machine Classification
Considerations for a Monitoring Scheme
Outline of the Text
Software
References


Data Presentation
Introduction
Presentation Formats
Comparison with Calculations
Detection and Diagnosis Process
Problems
References


Modelling and Analysis
Introduction
Need for Models
Modelling Approaches
Analysis Methods
Further Modelling Considerations
Summary
Problems
References


Faults in Machines – Part 1
Introduction
Definitions: Rigid and Flexible Rotors
Mass Imbalance
Rotor Bends
Concluding Remarks
Problems
References


Faults in Machines – Part 2
Introduction
Misalignment
Cracked Rotors
Torsion
Non-Linearity
Interactions and Diagnostics
Closing Remarks
Problems
References


Rotor–Stator Interaction
Introduction
Interaction through Bearings
Interaction via Working Fluid
Direct Stator Contact
The Morton Effect
Harmonics of Contact
Concluding Remarks
Problems
References


Machine Identification
Introduction
Current State of Modelling
Primary Components
Sources of Error/Uncertainty
Model Improvement
Application to Foundations
Imbalance Identification
Extension to Misalignment
Future Options
Problems
References


Some Further Analysis Methods
Standard Approaches
Artificial Neural Networks
Merging ANNs with Physics-Based Models
Kernel Density Estimation
Rapid Transients: Vold–Kalman Method
Useful Techniques
Concluding Remarks
Problems
References


Case Studies
Introduction
Crack in a Large Alternator Rotor
Workshop Modal Testing of a Cracked Rotor
Gearbox Problems on a Boiler Feed Pump
Vibration of Large Centrifugal Fans
Low-Pressure Turbine Instabilities
Concluding Remarks
Problems
References


Overview and Outlook
Progress in Instrumentation
Progress in Data Analysis and Handling
Progress in Modelling
Expert Systems
Future Prospects
Summary
References