Effects of Crack Length and Flank Angle Size on Fatigue Strength at Toes of Mild Steel Welded Joint : Fracture Mechanics Analysis of Fatigue Strength of Welded Joints, 2nd Report

概要

論文の詳細を見る
Fatigue tests were carried out on mild steel welded joints with various toe configurations and on simulated machined specimens. Fatigue crack propagation behavior and the fatigue endurance limit at the toes of the joints were observed. Furthermore, a stress intensity factor of a crack emanating from a toe was calculated by a finite element method. Since a weld toe is a kind of wedge, it has a stress singularity. The fatigue crack growth rate at the toe can be calculated with the maximum principal stress intensity factor and the fatigue crack characteristics of the material. The fatigue limit of the welded joint which had a toe crack or an under-cut was well expressed by a non-linear formula which was derived considering cyclic elastic-plastic phenomena at a crack tip and a stress concentration effect of a weld reinforcement. When the crack depth becomes very small, the fatigue limit levels off and this asymptotic strength is very close to the values obtained for as-welded joints without under-cut and the wedge shaped machined specimens. The fatigue crack propagation under pulsating compression showed a peculiar behavior, which was also discussed with cyclic elastic-plastic conditions at the toe.
社団法人溶接学会の論文