Faults in Machines (2)
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Faults in Machines (2) book
In this chapter, the study turns to some of the rotor faults other than imbalance and bends. The discussion begins with misalignment, which is very complex and which still lacks a comprehensive theory. The consequences of misalignment are outlined and a discussion of a rotor’s catenary is given together with correction methods. After outlining the type of flexible couplings, recent studies on the dynamics of so-called rigidly coupled rotors are outlined and from this discussion the complexity of the phenomena becomes clear. The chapter proceeds to a discussion of cracked rotors. Both natural frequencies and forced response are analyzed as both have an important role to play in the detection of cracked rotors on operational plant. An issue which is often neglected is torsional vibration and this is discussed relating to several plant types. It assumes special relevance in geared systems and methods of modeling the processes are discussed. This is another area in which nonlinearities can arise and a general account of nonlinearity effects is given. A summary is then given of the three main sources of instability. The chapter closes with a discussion of the ways in which various faults can interact to yield a very complex behavior pattern.