The mechanism of corrected mean stress effect in life equivalent method and in damage equivalent method has been analysed

a correction formula for calculating the mean stress in damage equivalent method being given.Taking material of coupling between the low-pressure cylinder and generater

i.e.the 26Cr2Ni4MoV steel

as an example

the fatigue damage of dangerous section under asymmetric loading of constant amplitude and non-constant amplitude has been calculated by using the finite-element method(ANSYS software).In the event of calculating the fatigue life damage under symmetric cyclic loading of constant amplitude

the difference between calculating precision of two said mehtods is slight

but in the case of caculating fatigue life damage under complex loading

the damage equivalent method with mean stress effect can substantially enhance the evaluation precision of the fatigue life damage.