Method for assessing ultra-high cycle fatigue strength and fatigue life of steam turbine rotor

Abstract

The invention discloses a method for assessing ultra-high cycle fatigue strength and fatigue life of a steam turbine rotor. The method comprises the following steps of: obtaining mean stress of high-temperature dangerous points and stress amplitude of the high-temperature dangerous points on a rotor component according to sigma<m>=(sigma<max>+sigma<min>) / 2 and sigma=(sigma<max>-sigma<min>) / 2; obtaining an ultra-high cycle fatigue S-N curve of the rotor component; obtaining fatigue strength corresponding to a service period of the rotor component according to the ultra-high cycle fatigue S-N curve of the rotor component; obtaining an equivalent unidirectional symmetric stress amplitude of on-load stable operation of the rotor component according to sigma<ea>=sigma+(sigma<m>*sigma<-1D>) / sigma<Creep>; determining an allowable security coefficient of the rotor component; checking the ultra-high cycle fatigue strength of the rotor component according to the allowable security coefficient of the rotor component; and calculating a security fatigue life and an ultra-high cycle fatigue life loss of the rotor component. The method for assessing the ultra-high cycle fatigue strength and fatigue life of the steam turbine rotor can realize the quantitative calculation and assessment of the high-temperature ultra-high cycle fatigue strength, fatigue life and loss.

Description

technical field

[0001] The invention relates to the technical field of steam turbines, in particular to a method for evaluating the ultra-high cycle fatigue fatigue strength and fatigue life of a steam turbine rotor. Background technique

[0002] During the service period, the steam turbine rotor not only bears the low cycle fatigue load caused by thermal stress, but also bears the ultra-high cycle fatigue load caused by the gravity of the rotor and blades under high temperature environment. For a steam turbine at full speed, the fatigue cycle loading frequency is 50Hz. If it is calculated based on an average annual operation of 8000 hours, then in the 30-year service period, the ultra-high cycle fatigue cycle is as high as 4×10 10 Weeks, well beyond the regular 1×10 7 The design range of cycles is a typical high-temperature ultra-high cycle fatigue failure problem. The value of ultra-high cycle fatigue load is relatively small, far below the yield limit, so it can often b...

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