Study on fatigue notch factor

Fatigue notch factor K_f expressing material fatigue notch sensibility is a key coefficient for structure strength prediction. So, the definitions of K_f and main influencing factors on it are discussed, and the formulae for calculating K_f using different methods and assumptions are outlined with the applications of the formulae depicted. It is concluded that Peterson's formula is more practical than other formulae for calculating K_f and test data fitting and local stress-strain method are also effective to determine K_f. And new formulae for calculating K_f will be developed with the progress of fracture mechanics and stress field intensity approach.