Fatigue Life of Welded and Bolted Repair Parts

Abstract

Fatigue crack propagation and residual stress measurement tests were conducted by using deep‐notched wide plate specimens with repaired parts. The main purpose of this study was to evaluate numerically the effects of some weld repair methods and a mechanically patching method with high strength grip bolts on residual fatigue life. The test results proved that the conventional welded repair method with no special treatment reduced fatigue life due to high tensile residual stress induced by welding repairs. However, through application of adequate treatment to cracks, compressive residual stress was induced in repair welds to increase the fatigue life. The remaining fatigue life of welded repair parts was further investigated using Fracture Mechanics. The patching method with high strength bolts and welded splice plates, on the other hand, had a remarkable effect on retarding the fatigue crack growth rate by decreasing it after bolted repairs to about 1/100‐1/1,000.