Abstract
In order to estimate the crack initiation life of notched specimen, it is necessary to obtain the stress or strain at the notch root. For this purpose, Neuber's equation and Stowell's equation have been proposed, but the measured strain at the notch root does not always correspond to the strain calculated with these equations.
So, some elasto-plastic analysis by FEM on side notched plates were carried out by using various stress-strain relations, and a new empirical equation which can well represent these calculation results is proposed as follows.
(Kt-1)/(Kσ-1)-1=2.4{Kε-1)/(Kt-1)-1}
where Kt, Kσ and Kε are the elastic stress concentration factor, the plastic stress concentration factor and the plastic strain concentration factor, respectively.
Besides, it was shown that the fatigue test results for S15C steel were in good agreement with the fatigue life estimated with this equation.
