Fracture Assessment of Cracked Welded Structures Considering the Heterogeneity of Welded Joints

The crack-like defects often cause the failure of welded structures. Most of the fracture assessment procedures that are used for solving this problem are based on deterministic approaches, for example Zerbst (2007). But the experimental results show that the mechanical properties and fracture toughness of welded joints are significantly changing with a random variation. Taking this into account the fracture assessment of welded structures requires improved numerical approaches. A numerical model of heterogeneous welded joint with randomly varying yield strength was proposed. The results show that the mechanical heterogeneity leads to higher J-integral values for the defects. This implies that neglecting the mechanical heterogeneity of welded joints results in underrating of the risk of failure of welded structures. The proposed numerical estimation of the fracture toughness is used for some typical welded joints and thin-walled pressure vessel. The relations between the variation of yield strength in cracked welded joints and J-integral are presented as the correction functions for calculated parameter of crack resistance.