Abstract
In this study, new evaluation method of local strain for the fracture assessment of the crack in the strain concentration was proposed. This method based on the relationship between the definition of local strain applied to the assessment method for brittle fracture of steel-frame structure WES2808-03 and liner fracture mechanics.
2-dimensional FE-analyses of the cross weld joint models with weld toe crack were conducted. Local strains at the stress concentration were calculated by the proposed method and CTODs were measured. And the relationships between local strains and CTODs were discussed. These results were compared with the CTOD design curve employed in WES2805-97 and the Level 2 FAD employed in BS7910-99, and the accuracy of assessment curves was investigated. The results demonstrate that the CTOD design curve gives slightly conservative estimation but FAD gives unsafe estimation in the case of Lr > 1.
The relationship among stress concentration factor and crack size and K-value was also investigated, and the suitability of estimation equation of strain concentration factor employed in WES2805 was discussed. The equation gives smaller strain concentration factor, but the influence of the results on the CTOD estimation by CTOD design curve is not serious.
