Limit load solutions of V-groove welded pipes with a circumferential crack at the centre of weld

摘要

The accurate estimation of limit loads are important for defect assessment and are strongly related with strength mismatch and weld geometry. Previous closed form solutions of mis-match limit loads were proposed by J-S Kim et al. (2009), for idealized butt weld configuration and are a function of the strength mis-match ratio with only one geometry-related slenderness parameter. Present work reports mis-match limit loads for V-groove welded pipe for a circumferential crack via detailed 2D and 3D FE analysis. Fully-circumferential surface crack and part-through surface crack are considered and are located at the centre of the welds with various groove angles. With regards to loading condition, axial (longitudinal) tension is applied for all cases. For the parent and weld metal, elastic-perfectly plastic materials are varied systemically to analyze under-matching and over-matching conditions in plasticity. To integrate the effect of groove angles on mis-match limit loads, one geometry-related slenderness parameter was modified by relevant geometric parameters including groove angle, crack depth, crack width and root opening, based on plastic deformation patterns in theory of plasticity.