Stress concentration effects of undercut defect and reinforcement metal in butt welded joint

In the present study, stress distribution of butt welded joints with various amounts of reinforcement metal and undercut defect has been investigated under uniaxial tension for a full penetration by systematically conducting a series of two-dimensional finite element (FE) models. The FE analysis indicated that the amount of reinforcement metal in weld zone has an important effect on stress distribution. For 120° of the reinforcement angle that designating reinforcement metal in weld joint, and 0.5 mm of toe radius, the value of stress concentration factor (SCF) exceeds 3.3σ0. The analyses show that SCF takes much higher values in both low reinforcement angle and ratio of toe radius to plate thickness (R/t). As for joints with undercut defects, it is concluded that severity of SCF is mainly controlled by the ratio of depth to radius of undercut (h/r) and width (W). In addition to undercut defect, the presence of reinforcement metal, SCF noticeably increases with decreasing the reinforcement angle; it attains maximum value (7.4σ0) for h/r = 5 and W = 3 mm. However, for the joints having wider undercut defects, the influence of reinforcement metal on SCF is found to be relatively lower; SCF is 6.7σ0 for W = 6 mm. Finally, an attempt has been made to construct simple relationships among the SCF of the weld joint, reinforcement angle, undercut defect and dimensionless parameters defining weld toe detail.