Bashta D. Fatigue damage of turbine unit shafts caused by torsional vibrations

The method of fatigue damage calculation in turbine unit shafts that occur in the re-sult of torque oscillations in emergency conditions is developed in the thesis. The solutions of scientific and technical problems of fatigue damage of turbine unit shafts caused by tensional vibrations under operational and technological factors are pre-sented. The analysis is carried out and key performance factors which significantly affect the fatigue flaking and development of fatigue damage of turbine unit shafts are identified. Torque values that cause oscillation processes of turbine shafts in contingency operation conditions are calculated. Calculation and analysis of torsion stress along the length of K-200-130 three-dimensional finite-element model of turbine unit shaft under determined conditions of load and affixment are carried out, cross sections that are the most dangerous as to intensity of applied stress are determined. Time of short circuit that can be dangerous and interval of phase-shift angle in asynchronous switching of turbo generator in power supply are meas-ured. The influence of pulse shape, time and rate on stress intensity in the most dangerous sections along the length of turbine unit shaft is examined. Relations between damage of shaft material and amplitude and time of reactive torque that occurs in turbo generator are established. Based on results of calculations the prediction of boundary fatigue damage of turbine shaft caused by torsional vibrations is performed.