Fatigue Strength Analysis of Ship’s Welded Structures Based on Method of Notch Stress

To address the fatigue strength problem of ship structures, the notch stress method is applied to typical structural joints focusing on weld toe and weld root. First, the basic principles of notch stress method and the notch fatigue analysis process of ship structure are introduced. Then, six typical joint types are set up for the double bottom structure of a product oil tanker. The local notch stress analysis of the fatigue hot spot is conducted using the finite element sub-modeling technology, allowing the determination of the notch stress concentration factor at the weld toe and weld root. Finally, based on the harmonised common structural rules (HCSR), the fatigue load and load condition of the ship structure are calculated, and the fatigue analysis of six typical joint types is performed. The results show that under the same load conditions, the notch stress concentration factor at the weld toe of each hot spot is smaller than that at the weld root, and the joint type 3 has the lowest fatigue damage value among the joint types, which suggests this type can improve the fatigue resistance of the hull.