Taking the common 40CrNiMoA steel for turbine rotor as an example

mathematic model describing the fatigue crack growth rate during the whole process was established

based on the Paris

Forman and Zheng-Hirt formulae.Immune algorithm was adopted to conduct optimization calculation on this model.The final optimized results were consistent with the experimental rules

indicating that the immune algorithm has good performance on dealing with the nonlinear fatigue crack growth rate model with multiple parameters.When the steel is at room temperature and with a constant stress ratio

this model can easily realize stable material life prediction and is more suitable for the real crack growth rate forecast.