FRACTURE ASSESSMENT OF STRUCTURAL COMPONENT WITH RESIDUAL STRESS ON THE BASIS OF THE WEIBULL STRESS CRITERION

This paper studies the method for estimating the residual stress effects on brittle fracture of structural component based on the Weibull stress criterion. Experiments show that the critical CTOD and the critical load of wide plate with welding residual stress are apparently smaller than those of wide plate without residual stress. It has been found that the critical CTODs of wide plate with and without residual stress can be predicted from the 3PB fracture toughness test results based on the Weibull stress criterion. Constraint loss effects on CTOD of wide plate with residual stress can be assessed by the equivalent CTOD ratio. The equivalent CTOD ratio beta is defined as the ratio, beta =delta/delta(WP), where delta and delta(WP), are CTODs of the standard fracture toughness specimen and wide plate, respectively, at the same level of the Weibull stress. Calculation results of beta are also shown for various residual stress levels and crack lengh based on the Weibull stress criterion. Fracture assessment results using beta are shown within the context of CTOD design curve. An excessive conservatism observed in the conventional procedure is reasonably reduced by applying the equivalent CTOD ratio, beta.