Vibration analysis and geometry-based modelling of a transverse fatigue crack in a rotating shaft

Abstract

The foremost focus of this thesis is to develop analytical tools that improve society's collective understanding of the behavioural mechanisms and indicators of fatigue cracks in a rotating shaft. This focus is followed by the desire to improve the likelihood of detecting fatigue cracks in real rotating machinery before failure occurs. Since analytical models of fatigue cracks in rotating shafts are complex and multifaceted, this thesis will narrow the scope by examining the effects of rotating unbalance, vibration, neutral axis orientation and crack-front shape on the breathing behaviour of a fatigue crack in a shaft, and the stiffness changes and vibration of a cracked rotor. The crack type chosen for analysis throughout this thesis is a singular transverse fatigue crack that occurs due to high-cycle fatigue of the rotor shaft as it is occurs quite often in real rotating machinery. A typical precursor for detecting the presence of fatigue cracks in rotating machinery is to develop a robust mathematical or software model that describes the behaviour of fatigue cracks under a variety of conditions. In this thesis, analytical models and three-dimensional finite element software models are the chosen methods for developing new crack breathing models and predicting the vibration of a cracked rotor using the new models.

Date of Award	2020
Original language	English