Bimodal Concept of High‐cycle Fatigue Life Prediction for Constant and Variable Amplitude Fatigue

Abstract

A bimodal concept for the prediction of the high‐cycle fatigue life of structural details subjected to constant‐ or variable‐amplitude loading is considered in this paper. The total fatigue life was separated into two phases: crack initiation and crack propagation. The portion of life spent in crack initiation was estimated by using S–N data obtained on smooth specimens. A fracture mechanics concept was used to calculate the portion of life spent in crack propagation, and the S–N curve, including the fatigue limit of a structural detail, was determined by using material properties and the geometry of the detail. The bimodal concept was applied to a welded stiffener and the results are compared with experimental data reported in the literature.