Abstract
In the present paper, Elasto-Plastic Fracture Mechanics (EPFM) was applied to an assessment of initial defect in fatigue design.
Considering fatigue design methods of welded steel structures, assessment methods of iditial defect in notched components were classified into three cases.
In the Case 1, fatigue design is based on joint classification, where allowable size of initial defect is specified according to joints shape. Safety factor to fatigue life varied with shape of components.
In the Case 2A, fatigue design is based on joint classification, where allowable size of initial defect is, in this case, assessed by ΔJ and experimental method. The size depends upon stress level and materials (SS41 or HT80).
And in the Case 2B, fatigue desing is based on apriori specified initial defect size and EPFM. By this design method, to increase sectional area is better than to decrease tensile residual stress when fatigue strength is critical in low cycle region, and vice versa.
