Method for measuring shafting mechanical fatigue of turbine generator set

A measuring method of mechanical fatigue in turbine-generator shafting, comprising the steps of:

• 1) determine a lumped mass model and parameter of a turbo-unit;
• 2) compute torsional mode frequency and vibration curve based on a mass block model;
• 3) capture changes of palstance Δω, then obtain the change of palstance Δω1, Δω2, Δω3 . . . Δωn in different modes are
• Δωk=Δωk*sin(ωkt)/[ωk*cos(ωkt)]
• where
• Δωk=Akωk cos(ωkt), Δθk=Δωkt=Ak sin(ωkt), (k=1, 2, 3, . . . n), ωk=2πfk,
• Δθk:
• terminal rotation angle of each mode;
• AK:
• palstance changing amplitude of each mode;
• fk:
• mode frequency;
• 4) according to a mode frequency, vibration curve and equivalent spring constant of the lumped mass model of the turbo-unit, calculate a torque on each cross-sections of the shafting, obtain a torque-time history plot;
• 5) compute a cumulative fatigue value of the all the cross-sections of the shafting caused by a specific vibration, namely the mechanical fatigue of the turbine generator shafting.