Examination of fatigue resistance in turbine rotors on large models

Abstract

Increased power levels at thermal and nuclear power stations have resulted in a substantial increase in the mechanical loads.The rotor is one of the most highly loaded parts [I]~ Apart from large dimensions (length up to 15,000 mm and diameter up to 1500 mm), the rotor in a turbine generator has many stress concentrators.The working reliability of such a component is determined by the fatigue resistance.Analysis of rotor failures indicates that an important part in the fatigue damage is played by the stress concentrations under working conditions.Very often, fatigue cracks occur at a place where two or more stress concentrators are localized, such as annular and segment grooves, pressed fittings, and holes for pins.Under the nominal working conditions, the growth of the fatigue cracks usually leads to increased vibration of the rotor, which is transmitted to the bearings, which enables one to stop the system in good time and thus avoid complete failure.

Assessment of fatigue damage in steam turbine shafting due to torsional vibrations

“…As applied to turbine rotors of thermal stations, these factors include a load ratio [6], high temperature [7], scale factor [8,9], stress concentration [9], nonuniformity of mechanical properties of steal in the rotor volume [10,11], etc. They should be allowed for, in order to achieve a reliable assessment of cyclic damage in a turbine shafting under vibration conditions.…”