A Simple Estimation Method of the Normal Stress over the Cross-Section of a Plate at Weld Toe

Abstract

Many fatigue damages in large welded built-up structures are found near a boxing fillet weld toe. These fatigue cracks usually initiate from the toe and propagate in the cross-section of wall thickness as surface cracks.Many attempts based on fracture mechanics for the improvement of fatigue life estimation are proposed, because current practical methods based on the S-N curves and the cumulative damage rules cannot estimate the accurate fatigue life under in-service structures. Whereas stress distributions along the fatigue crack path must be given in order to apply fracture mechanics methods for the precise fatigue life estimation, no stress distribuiton along the path is calculated because the shell type elements are used in finite element analyses in practical structural design stages.A simple estimation method of the stress distribution over the cross-section of a plate at weld toe, which corresponds to the supposed fatigue crack path in the case mentioned above, is proposed in this paper. The validity of this method is confirmed by comparing estimation results with ones by finite element analyses in which solid type elements are used.