Fatigue evaluation of FV520B-I shrouded impeller blade with fatigue crack based on FEA and fracture mechanics.

A specific fatigue life prediction model for FV520B-I blade with fatigue crack is developed with the comprehensive consideration of ultrasonic fatigue test, FEA and influencing factor of fatigue failure, including ultrahigh loading frequency, stress amplitude, surface roughness and dimension. All these factors are involved in the analysis process, to guarantee the applicability and rationality of the fatigue life prediction model in actual operational condition of FV520B-I blade. • A new quantitative formula between stress σ m and fatigue crack Sc is proposed. • A specific stress intensity factor mode is proposed with parameter as Y = 0.68. • The fatigue limit of FV520B-I is estimated as 450 MPa according to the test. • A specific fatigue life model for FV520B-I blade with fatigue crack is proposed. The fatigue life prediction of FV520B-I blade with fatigue crack is a critical study in the fatigue analysis of shrouded impeller. However, the relationship between fatigue crack and fatigue life of FV520B-I blade has not been well studied. In this paper, finite element analysis (FEA) for FV520B-I blade with fatigue crack is conducted; both centrifugal load and aerodynamic load involved, and the stress distribution and the fatigue failure at decisive positions are analyzed. The new correlation between mean stress and fatigue crack is found based on the results of FEA, which is helpful to the development of fatigue life model of FV520B-I blade. Then fatigue test for blade material FV520B-I is performed to determine the fatigue limit. A fatigue life evaluation model for FV520B-I blade is then achieved, by taking fatigue crack as main variable, combining with the comprehensive application of FEA, fatigue test, actual operating parameters and existing fatigue modeling theory. The model is proved to be reliable by comparing the theoretical predicted life with simulated one. Study on fatigue life evaluation method of FV520B-I blade with fatigue crack is novel and essential to improve precision of fatigue life prediction of shrouded impeller in engineering practice. [ABSTRACT FROM AUTHOR]